DeepSeek V4.1 Flash (Venice) (thinking on) on Animated fireplace in one self-contained HTML file

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        "reasoning_content": "Let me create a self-contained HTML file with an animated fireplace. Let me check the working directory first.\n\nLet me just write the file. I'll use canvas with requestAnimationFrame for flames, embers, glow. Also include CSS @keyframes for good measure, and infinite animation.\n\nLet me be careful about the checks:\n- No `//` URLs anywhere in src/href/etc. Avoid `//` in general? The check says no `http://`, `https://` or `//` URLs in src, href, srcset, poster, action, data or url(). So avoid `//` in those attributes. Also avoid `@import`, `fetch(`, etc.\n- Careful: `//` might appear in JS comments. The check specifically mentions URLs in those attributes, but \"no asset URLs anywhere\". To be safe, avoid `//` sequences entirely in the file. Hmm, that's tricky with JS. Let me avoid `//` comments and avoid `//` anywhere. Actually division like `a / b` is fine. Just avoid double slashes.\n\nLet me write clean code without `//`.\n\nAlso avoid `import` keyword in JS. Avoid `fetch(`.\n\nLet me design:\n\nCanvas-based fireplace. Full page dark background. A hearth with logs, flames drawn with layered gradients, embers rising, glow pulsing.\n\nAlso add CSS @keyframes for a subtle glow overlay to satisfy static checks robustly.\n\nLet me write it.\n\nStructure:\n- <title>Cosy Fireplace</title>\n- <div id=\"fireplace\"> containing canvas and maybe overlay divs.\n\nCanvas animation with rAF, no cancelAnimationFrame.\n\nLet me write the JS carefully.\n\nFlame rendering: use particle system. Each flame particle has x, y, vy, life, size, hue. Draw with radial gradients using 'lighter' composite.\n\nEmbers: small bright dots rising with flicker.\n\nGlow: radial gradient at bottom center, pulsing with sin.\n\nLogs: draw a few rounded rects with brown gradient.\n\nLet me write.\n\nI'll make canvas resize to window.\n\nLet me code:\n\n```html\n<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"utf-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">\n<title>Cosy Fireplace</title>\n<style>\n  html, body { margin:0; padding:0; height:100%; background:#0a0605; overflow:hidden; }\n  #fireplace { position:fixed; inset:0; }\n  canvas { display:block; width:100%; height:100%; }\n  .glow {\n    position:absolute; left:50%; bottom:-10%; width:120%; height:80%;\n    transform:translateX(-50%);\n    background:radial-gradient(ellipse at 50% 100%, rgba(255,140,40,0.35), rgba(255,80,0,0.12) 45%, rgba(0,0,0,0) 70%);\n    pointer-events:none;\n    animation: breathe 3.2s ease-in-out infinite;\n    mix-blend-mode: screen;\n  }\n  @keyframes breathe {\n    0%   { opacity:0.55; transform:translateX(-50%) scale(1); }\n    50%  { opacity:0.95; transform:translateX(-50%) scale(1.06); }\n    100% { opacity:0.55; transform:translateX(-50%) scale(1); }\n  }\n</style>\n</head>\n<body>\n<div id=\"fireplace\">\n  <canvas id=\"c\"></canvas>\n  <div class=\"glow\"></div>\n</div>\n<script>\n...\n</script>\n</body>\n</html>\n```\n\nWait, `inset:0` fine.\n\nNow JS. Avoid `//`.\n\n```js\n(function(){\n  var canvas = document.getElementById('c');\n  var ctx = canvas.getContext('2d');\n  var W = 0, H = 0, DPR = Math.min(window.devicePixelRatio || 1, 2);\n\n  function resize(){\n    W = canvas.clientWidth;\n    H = canvas.clientHeight;\n    canvas.width = Math.floor(W * DPR);\n    canvas.height = Math.floor(H * DPR);\n    ctx.setTransform(DPR,0,0,DPR,0,0);\n  }\n  window.addEventListener('resize', resize);\n  resize();\n\n  var flames = [];\n  var embers = [];\n  var sparks = [];\n\n  function rand(a,b){ return a + Math.random()*(b-a); }\n\n  function spawnFlame(){\n    var baseX = W*0.5;\n    var spread = W*0.16;\n    flames.push({\n      x: baseX + rand(-spread, spread),\n      y: H*0.86 + rand(-10,10),\n      vx: rand(-0.25,0.25),\n      vy: rand(-2.6,-1.4),\n      life: 1,\n      decay: rand(0.006,0.013),\n      size: rand(18,46),\n      hue: rand(8,42)\n    });\n  }\n  ...\n})();\n```\n\nHmm, sizes relative to canvas. Let me scale by H.\n\nActually let me make it resolution-independent using a scale factor s = H/600.\n\nLet me just write with relative units.\n\nFlame particle: size in px scaled.\n\nLet me write full code:\n\n```js\n(function(){\n  var canvas = document.getElementById('c');\n  var ctx = canvas.getContext('2d');\n  var W = 0, H = 0, DPR = Math.min(window.devicePixelRatio || 1, 2);\n  var t = 0;\n\n  function resize(){\n    W = canvas.clientWidth || window.innerWidth;\n    H = canvas.clientHeight || window.innerHeight;\n    canvas.width = Math.max(1, Math.floor(W * DPR));\n    canvas.height = Math.max(1, Math.floor(H * DPR));\n    ctx.setTransform(DPR, 0, 0, DPR, 0, 0);\n  }\n  window.addEventListener('resize', resize);\n  resize();\n\n  function rand(a, b){ return a + Math.random() * (b - a); }\n\n  var flames = [];\n  var embers = [];\n\n  function spawnFlame(){\n    var s = H / 600;\n    var spread = W * 0.14;\n    flames.push({\n      x: W * 0.5 + rand(-spread, spread),\n      y: H * 0.88 + rand(-8 * s, 8 * s),\n      vx: rand(-0.3, 0.3) * s,\n      vy: rand(-2.4, -1.2) * s,\n      life: 1,\n      decay: rand(0.008, 0.016),\n      size: rand(16, 44) * s,\n      hue: rand(6, 44),\n      wob: rand(0, 6.28),\n      wobAmp: rand(0.4, 1.6) * s\n    });\n  }\n\n  function spawnEmber(){\n    var s = H / 600;\n    var spread = W * 0.12;\n    embers.push({\n      x: W * 0.5 + rand(-spread, spread),\n      y: H * 0.9,\n      vx: rand(-0.4, 0.4) * s,\n      vy: rand(-1.6, -0.6) * s,\n      life: 1,\n      decay: rand(0.004, 0.01),\n      size: rand(1, 2.6) * s,\n      hue: rand(20, 45)\n    });\n  }\n\n  function drawLogs(){\n    var s = H / 600;\n    var cx = W * 0.5;\n    var baseY = H * 0.9;\n    ctx.save();\n    ctx.translate(cx, baseY);\n    var logs = [\n      { x: -70 * s, y: 0, w: 150 * s, h: 26 * s, r: -0.12 },\n      { x: 60 * s, y: -6 * s, w: 150 * s, h: 26 * s, r: 0.14 },\n      { x: -6 * s, y: -22 * s, w: 130 * s, h: 24 * s, r: 0.02 }\n    ];\n    for (var i = 0; i < logs.length; i++){\n      var L = logs[i];\n      ctx.save();\n      ctx.translate(L.x, L.y);\n      ctx.rotate(L.r);\n      var g = ctx.createLinearGradient(0, -L.h/2, 0, L.h/2);\n      g.addColorStop(0, '#5a3520');\n      g.addColorStop(0.5, '#3a2013');\n      g.addColorStop(1, '#1c0f08');\n      ctx.fillStyle = g;\n      roundRect(ctx, -L.w/2, -L.h/2, L.w, L.h, L.h/2);\n      ctx.fill();\n      ctx.restore();\n    }\n    ctx.restore();\n  }\n```\n\nHmm, drawing logs each frame is fine.\n\nActually maybe simpler: draw logs once to an offscreen canvas? Not necessary.\n\nLet me include roundRect helper.\n\nFlame drawing: for each flame, draw radial gradient circle with 'lighter'.\n\n```js\n  function drawFlame(f){\n    var r = f.size * (0.6 + 0.4 * f.life);\n    var g = ctx.createRadialGradient(f.x, f.y, 0, f.x, f.y, r);\n    var a = Math.max(0, f.life) * 0.5;\n    g.addColorStop(0, 'hsla(' + f.hue + ', 100%, 72%, ' + a + ')');\n    g.addColorStop(0.35, 'hsla(' + (f.hue + 8) + ', 100%, 55%, ' + (a * 0.7) + ')');\n    g.addColorStop(0.7, 'hsla(' + (f.hue + 16) + ', 100%, 40%, ' + (a * 0.3) + ')');\n    g.addColorStop(1, 'hsla(' + (f.hue + 20) + ', 100%, 30%, 0)');\n    ctx.fillStyle = g;\n    ctx.beginPath();\n    ctx.arc(f.x, f.y, r, 0, Math.PI * 2);\n    ctx.fill();\n  }\n```\n\nComposite 'lighter' gives nice additive glow.\n\nEmber drawing: small bright dot with glow.\n\nGlow at base: radial gradient.\n\nBackground: dark with subtle vignette.\n\nLet me also add a warm flicker light on the whole scene: overlay radial gradient with alpha varying by noise.\n\nMain loop:\n\n```js\n  var last = performance.now();\n  function frame(now){\n    var dt = Math.min(50, now - last) / 16.6667;\n    last = now;\n    t += dt;\n\n    ctx.setTransform(DPR,0,0,DPR,0,0);\n    ctx.globalCompositeOperation = 'source-over';\n    ctx.fillStyle = '#0a0605';\n    ctx.fillRect(0,0,W,H);\n\n    drawBackgroundGlow();\n    drawLogs();\n\n    ctx.globalCompositeOperation = 'lighter';\n\n    var s = H/600;\n    var spawnCount = Math.max(1, Math.round(3 * dt));\n    for (var i=0;i<spawnCount;i++) spawnFlame();\n    if (Math.random() < 0.5 * dt) spawnEmber();\n\n    for (var j=flames.length-1;j>=0;j--){\n      var f = flames[j];\n      f.wob += 0.08 * dt;\n      f.x += (f.vx + Math.sin(f.wob) * f.wobAmp * 0.06) * dt;\n      f.y += f.vy * dt;\n      f.vy *= (1 - 0.004 * dt);\n      f.life -= f.decay * dt;\n      if (f.life <= 0 || f.y < H*0.1){ flames.splice(j,1); continue; }\n      drawFlame(f);\n    }\n\n    for (var k=embers.length-1;k>=0;k--){\n      var e = embers[k];\n      e.x += e.vx * dt;\n      e.y += e.vy * dt;\n      e.vy *= (1 - 0.002 * dt);\n      e.life -= e.decay * dt;\n      if (e.life <= 0){ embers.splice(k,1); continue; }\n      drawEmber(e);\n    }\n\n    ctx.globalCompositeOperation = 'source-over';\n    requestAnimationFrame(frame);\n  }\n  requestAnimationFrame(frame);\n```\n\nWait, `requestAnimationFrame(frame)` inside frame \u2014 fine, no cancel.\n\nBut careful: `performance.now()` fine.\n\ndrawBackgroundGlow: radial gradient at bottom center, alpha pulsing with sin(t*0.05).\n\nLet me write:\n\n```js\n  function drawBackgroundGlow(){\n    var s = H/600;\n    var cx = W*0.5, cy = H*0.92;\n    var pulse = 0.75 + 0.25 * Math.sin(t * 0.06) + 0.06 * Math.sin(t * 0.23);\n    var r = Math.max(W, H) * 0.75;\n    var g = ctx.createRadialGradient(cx, cy, 0, cx, cy, r);\n    g.addColorStop(0, 'rgba(255,150,50,' + (0.30 * pulse) + ')');\n    g.addColorStop(0.25, 'rgba(255,90,20,' + (0.16 * pulse) + ')');\n    g.addColorStop(0.6, 'rgba(120,30,0,' + (0.06 * pulse) + ')');\n    g.addColorStop(1, 'rgba(0,0,0,0)');\n    ctx.fillStyle = g;\n    ctx.fillRect(0,0,W,H);\n  }\n```\n\nHmm but this is drawn with source-over before logs, good.\n\nAlso add a \"floor\" reflection maybe. Keep simple.\n\ndrawEmber:\n\n```js\n  function drawEmber(e){\n    var a = Math.max(0, e.life);\n    var r = e.size * (0.6 + 0.8 * a);\n    var g = ctx.createRadialGradient(e.x, e.y, 0, e.x, e.y, r*4);\n    g.addColorStop(0, 'hsla(' + e.hue + ', 100%, 80%, ' + (a) + ')');\n    g.addColorStop(0.3, 'hsla(' + e.hue + ', 100%, 60%, ' + (a*0.5) + ')');\n    g.addColorStop(1, 'hsla(' + e.hue + ', 100%, 50%, 0)');\n    ctx.fillStyle = g;\n    ctx.beginPath();\n    ctx.arc(e.x, e.y, r*4, 0, Math.PI*2);\n    ctx.fill();\n  }\n```\n\nAlso add flicker to ember alpha: multiply by (0.6 + 0.4*Math.sin(t*0.5 + e.x)).\n\nNow, the check \"page_animates\": screenshots at 1.5s and 2.5s must differ. With continuous flame animation, definitely differ.\n\nCheck 4 browser part: page must still change between ~6s and ~7s. Continuous rAF, yes.\n\nNow about `//` avoidance: I have `Math.PI * 2` fine. No `//`. Let me double check no `http`, no `//`. The string `'hsla('` fine.\n\nCareful: `ctx.setTransform(DPR,0,0,DPR,0,0)` fine.\n\nOne concern: the check for `//` URLs \u2014 it looks for `//` in attributes like src/href. We have none. But also \"no asset URLs anywhere\". Our file has no `//` at all hopefully. Let me make sure comments use `/* */` or none. I'll avoid comments entirely.\n\nAlso avoid the word `import`. Fine.\n\nAlso `data:` URIs are fine but we don't need any.\n\nLet me also ensure `<title>` contains \"Fireplace\" \u2014 yes \"Cosy Fireplace\".\n\nid=\"fireplace\" \u2014 yes.\n\nNow let me also think: the scorer opens page with network blocked. Our page makes no requests. Good.\n\nPotential issue: `mix-blend-mode: screen` on glow div \u2014 fine.\n\nLet me also add a subtle CSS animation on the canvas? Not needed.\n\nLet me write the file and verify size and grep for forbidden patterns.\n\nLet me also double-check: \"no `//` URLs in ... `url()`\". We have no url(). Good.\n\nLet me write it.\n\nOne more: the glow div uses `radial-gradient` with rgba \u2014 fine.\n\nLet me also make sure the canvas fills and the glow div is positioned. `#fireplace { position:fixed; inset:0; }` and `.glow { position:absolute; ... }` relative to #fireplace. Good.\n\nNow write.\n\nActually, let me reconsider the flame look. Additive radial gradients of orange circles rising \u2014 should look decent. Add a bright core near base.\n\nLet me also add \"sparks\" occasionally that shoot up faster. Optional. Keep embers.\n\nLet me finalize code and write file.\n\nI'll also add a slight vertical stretch to flames by scaling context? Could draw ellipse. Let me draw ellipse for flame shape: ctx.ellipse(f.x, f.y, r*0.7, r*1.15, 0, 0, PI*2). That gives flame-like vertical shape. Good.\n\nLet me use ellipse.\n\nNow write the file.\n\nLet me compute: I'll write and then run checks.\n\nAlso need to handle `canvas.clientWidth` \u2014 canvas has width:100%;height:100% via CSS, and parent is fixed inset 0, so clientWidth works.\n\nLet me write.\n\nFor robustness in headless (no devicePixelRatio issues), fine.\n\nLet me write the file now.\n\nAlso, I should double check there's no `//` from things like `https` \u2014 none.\n\nWrite it.\n\nLet me also add `will-change` etc. Not needed.\n\nFinal code below.\n\nOne more consideration: `Math.min(window.devicePixelRatio || 1, 2)` \u2014 fine.\n\nLet me write.\n\nAlso the check might scan for `setInterval(` or `requestAnimationFrame(` \u2014 we have rAF. Good. And no `cancelAnimationFrame`. Good.\n\nWrite file.\n\nLet me also verify no `clearInterval`. Good.\n\nNow produce.\n\nI'll also add a small \"hearth\" base: a dark rounded rectangle / stone. Maybe draw a subtle floor gradient. Keep it.\n\nLet me write the final HTML.\n\nActually let me reconsider drawing logs every frame with gradients \u2014 createLinearGradient each frame \u00d73, fine performance-wise.\n\nLet me write.\n\nAlso add flicker to overall flame brightness: multiply alpha by (0.85 + 0.15*sin(t*0.3)).\n\nOK writing.\n\nLet me produce the content string carefully.\n\nI'll write the file with write_file.\n\nThen run: ls -l, grep for forbidden patterns, and maybe check with node? No browser likely. Let me check if chromium available.\n\nLet's go."
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        "reasoning_content": "Headless Chrome is available. Let me check the TASK.md and then write the file.\n\nLet me plan the fireplace HTML. Requirements:\n- id=\"fireplace\" element\n- <title> containing \"Fireplace\"\n- CSS @keyframes + animation, infinite\n- No external requests\n- Must change between 1.5s and 2.5s screenshots, and between 6s and 7s.\n\nI'll use canvas with requestAnimationFrame for flames, plus CSS animations for glow. Actually, to be safe, use both CSS keyframes infinite AND rAF. But careful: check 4 says rAF/setInterval with no cancelAnimationFrame/clearInterval anywhere. If I use rAF without cancel, that's fine. But if I also have CSS infinite animation, that's fine too.\n\nWait \u2014 check 4: \"an `infinite` CSS animation ... or rAF/setInterval with no cancelAnimationFrame/clearInterval anywhere\". So having CSS infinite satisfies it. Good.\n\nCheck 3: CSS @keyframes plus animation property, or rAF/setInterval. I'll have both.\n\nLet me make sure the canvas animation is deterministic-ish but changes over time. Use time-based animation so screenshots at 1.5s and 2.5s differ. Flames flicker continuously so they'll differ.\n\nImportant: headless Chrome screenshots \u2014 need to make sure rendering happens. Use requestAnimationFrame loop.\n\nAlso avoid any `//` in URLs. Note: `//` appears in comments potentially. The check looks for `//` URLs in src/href/etc. But also \"no asset URLs anywhere\". Let me be careful: avoid `//` sequences that could look like protocol-relative URLs. Actually the check likely regexes for `//` in attribute values. To be safe, avoid `//` in the HTML entirely? That's hard with JS comments. I'll avoid JS comments with `//` and use `/* */` instead. Also avoid `http://` etc.\n\nActually careful: things like `https://` won't appear. But `//` might appear in e.g. `x = a // b`? No. Let me just avoid `//` anywhere in the file to be maximally safe. Hmm, but CSS like `background: url(...)` no. Let's just avoid.\n\nWait, one issue: in JS, division isn't `//`. Fine.\n\nLet me write clean code without `//` comments.\n\nAlso avoid `import` keyword in JS. Avoid `fetch(`. Avoid `<link href>`. Avoid `<script src>`.\n\nLet me design a nice fireplace:\n\n- A dark room background with radial gradient glow.\n- A fireplace arch/brick surround drawn with CSS/SVG.\n- Canvas for flames and embers.\n- Logs at the bottom.\n- CSS animated glow overlay.\n\nLet me write it.\n\nCanvas flame rendering: use a particle system. Particles spawn at bottom, rise, shrink, change color from white/yellow to orange to red. Plus embers rising.\n\nTo make it look good, I'll draw flames with additive blending ('lighter') and radial gradients.\n\nLet me write the code.\n\nStructure:\n\n```html\n<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"utf-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">\n<title>Cosy Fireplace</title>\n<style>...</style>\n</head>\n<body>\n<div id=\"fireplace\">\n  <div class=\"room\"></div>\n  <div class=\"hearth\">\n    <canvas id=\"fire\"></canvas>\n    <div class=\"glow\"></div>\n    <div class=\"logs\">...</div>\n  </div>\n</div>\n<script>...</script>\n</body>\n</html>\n```\n\nHmm, canvas needs to be sized. Let me use a fixed 800x600-ish layout but responsive.\n\nLet me think about the visual: A brick fireplace with an arched opening. Inside, flames. Below, a hearth with logs and embers.\n\nI'll draw the brick surround with CSS gradients and box-shadows, or with SVG. SVG might be cleaner. But canvas is fine for flames.\n\nLet me do:\n- body: dark background, centered.\n- #fireplace: a container ~ 640x520.\n- Brick surround: a div with repeating-linear-gradient for bricks, with an inner cutout (the firebox) using a radial/inset shape. Use border-radius for arch top.\n\nActually simpler: firebox is a div with dark background and rounded top (border-top-left-radius etc.), and the brick surround is a bigger div behind it with brick pattern. The firebox sits inside with padding.\n\nLet me build:\n\n```\n.fireplace-frame {\n  position: relative;\n  width: 620px; height: 520px;\n  background: brick pattern;\n  border-radius: 18px 18px 8px 8px;\n  padding: 40px 40px 0 40px;\n  box-shadow: ...\n}\n.firebox {\n  position: relative;\n  width: 100%; height: 100%;\n  background: radial-gradient(...) dark;\n  border-radius: 220px 220px 0 0;  /* arch */\n  overflow: hidden;\n}\n```\n\nHmm, arch: border-radius top corners large. Let's do `border-radius: 50% 50% 0 0 / 40% 40% 0 0`? That makes an elliptical arch. Nice.\n\nInside firebox: canvas fills it. Logs drawn on canvas too, or as DOM elements. I'll draw logs on canvas for simplicity of layering, or use DOM divs positioned at bottom. Let me draw everything fire-related on canvas: logs, flames, embers, glow. That gives full control.\n\nActually drawing logs on canvas each frame is fine.\n\nCanvas resolution: use devicePixelRatio scaling.\n\nLet me write the flame particle system.\n\nParticle:\n- x, y, vx, vy, life, maxLife, size, hue/color.\n\nSpawn at base: x around center \u00b1 width*0.35, y at base line.\n\nUpdate: y -= vy*dt; x += vx*dt + noise; size shrinks; life decreases.\n\nRender: radial gradient circle with color based on life fraction: young = bright yellow/white, old = red/dark.\n\nUse globalCompositeOperation = 'lighter'.\n\nAlso add a soft glow behind.\n\nEmbers: small bright dots that rise higher, flicker, and fade.\n\nAlso add a subtle \"heat shimmer\"? Not needed.\n\nLet me also add CSS keyframe animations for the glow pulsing and maybe a vignette flicker, to satisfy check 3 with CSS too.\n\nNow, the check \"page_animates\": screenshots at 1.5s and 2.5s must differ. With continuous flame animation, definitely differ. But careful: if the canvas is drawn but the screenshot captures... yes it will differ.\n\nOne risk: headless Chrome screenshot timing. Should be fine.\n\nAnother risk: `requestAnimationFrame` may be throttled in headless? Usually works. To be safe, also use setInterval as a fallback? Actually rAF in headless Chrome (new headless) works. But if the page is not visible... headless screenshots typically still run rAF. Hmm, there's a known issue: in headless mode, rAF may not fire if the page is considered hidden. Actually with `--headless=new` and screenshot, rAF does fire. But to be extra safe, I could drive the animation with setInterval instead of rAF, or use both.\n\nCheck 4 says rAF/setInterval with no cancel/clear. Using setInterval is safe and definitely fires. Let me use setInterval at ~60fps (16ms) as the main loop. Actually setInterval in background tabs is throttled to 1s, but headless screenshot pages are usually foreground. Hmm.\n\nBetter: use both rAF and setInterval as a safety net, both calling the same render function, with a guard to avoid double-render in the same frame. Actually simplest: use rAF primarily, and a setInterval that calls render if rAF hasn't fired recently. Let me implement:\n\n```js\nvar last = 0;\nfunction frame(t){ ... render ... }\nfunction loop(){ requestAnimationFrame(loop); }\n```\n\nHmm, let me just do:\n\n```js\nvar lastTime = performance.now();\nfunction tick(now){\n  var dt = Math.min(0.05, (now - lastTime)/1000);\n  lastTime = now;\n  update(dt);\n  draw();\n}\nfunction rafLoop(){ requestAnimationFrame(rafLoop); tick(performance.now()); }\n```\n\nWait that double counts. Let me do it properly:\n\n```js\nvar lastTime = 0;\nfunction step(now){\n  if(!lastTime) lastTime = now;\n  var dt = (now - lastTime)/1000;\n  lastTime = now;\n  if(dt > 0.1) dt = 0.1;\n  update(dt);\n  draw();\n}\nfunction rafLoop(now){ step(now); requestAnimationFrame(rafLoop); }\nrequestAnimationFrame(rafLoop);\n```\n\nAnd a fallback interval:\n```js\nsetInterval(function(){ if(performance.now() - lastTime > 200){ step(performance.now()); } }, 100);\n```\nThis ensures if rAF is throttled, the interval still drives it. But if rAF is throttled to 1fps, lastTime updates each second, so the interval check `> 200` would be false most of the time... Actually if rAF fires once per second, lastTime is updated once per second, and the interval would see diff up to 1000ms > 200 and call step. That would cause extra steps. Fine, it just renders more.\n\nHmm, but that could cause double stepping. Not a big deal visually.\n\nActually, simpler and robust: just use setInterval as the sole driver at 16ms. In headless Chrome with a screenshot, the page is typically active. But there's risk of throttling. Let me use both: rAF loop + interval fallback. Good.\n\nActually, let me reconsider: the safest for \"page changes between 1.5s and 2.5s\" is that the animation is time-based and continuous. Both rAF and setInterval will produce change.\n\nLet me also make sure the canvas is drawn at least once immediately (synchronously) so there's content.\n\nNow let me also consider: the check for `//` \u2014 I must avoid `//` in the file. Let me scan my planned code. In CSS, `background: url()` \u2014 none. In JS, no `//` comments. Division uses `/`. But `*/` and `/*` are fine. Careful with things like `http://` \u2014 none.\n\nHmm, one thing: `<!DOCTYPE html>` fine. `xmlns` none.\n\nAlso avoid `//` in strings. E.g., no.\n\nLet me also avoid the substring `//` appearing in e.g. `100%//`? No.\n\nOK. Also avoid `import` as a word \u2014 \"import\" might appear in... no.\n\nAlso `fetch(` \u2014 no.\n\nLet me now write the file.\n\nLet me think about the visual design more concretely.\n\nColors:\n- Background room: very dark warm brown/black, radial gradient from fireplace.\n- Brick: dark reddish-brown bricks with mortar lines.\n- Firebox interior: near black with warm glow at bottom.\n- Flames: yellow-white core, orange, red tips.\n- Logs: dark brown with glowing embers on them.\n- Embers: orange dots rising.\n\nLayout: center the fireplace in viewport, 800x600 default. Let me make it responsive with vmin units so it fits 800x600.\n\nLet me use a container sized with `min(90vw, 90vh * something)`. Simpler: fixed size 640x480 centered, which fits in 800x600. Good.\n\nActually let's make it fill nicely: width 660px, height 500px. In 800x600 viewport that fits with margin.\n\nLet me structure:\n\n```html\n<div id=\"fireplace\">\n  <div class=\"frame\">\n    <div class=\"firebox\">\n      <canvas id=\"fire\"></canvas>\n      <div class=\"glow\"></div>\n    </div>\n  </div>\n  <div class=\"hearth\"></div>\n</div>\n```\n\nHmm, the hearth (floor slab) below the firebox.\n\nLet me simplify: \n\n#fireplace is the whole scene (position relative, width 660, height 520).\n- .frame: absolute inset 0, brick background, border-radius, box-shadow.\n- .firebox: absolute, left 60, right 60, top 70, bottom 0, arch top, dark interior, overflow hidden.\n- canvas inside firebox, absolute inset 0.\n- .glow: absolute, radial gradient, mix-blend-mode screen, animated opacity.\n- .hearth: absolute bottom, a slab.\n\nActually the firebox bottom should be at the hearth level. Let me just have the firebox extend to the bottom of the frame, and the hearth slab in front at the bottom.\n\nLet me write CSS.\n\nBrick pattern:\n```css\nbackground-color: #3a1f18;\nbackground-image:\n  linear-gradient(335deg, rgba(0,0,0,0.35) 0%, rgba(0,0,0,0) 60%),\n  repeating-linear-gradient(0deg, rgba(0,0,0,0.5) 0 2px, rgba(0,0,0,0) 2px 26px),\n  repeating-linear-gradient(90deg, rgba(0,0,0,0.5) 0 2px, rgba(0,0,0,0) 2px 52px);\n```\nThat gives a grid. For offset bricks, use two repeating gradients with offset. Eh, a simple grid is fine.\n\nActually let me do a nicer brick with offset rows using background-position on a second layer. Keep it simple.\n\nLet me now write the JS.\n\n```js\n(function(){\n  var canvas = document.getElementById('fire');\n  var ctx = canvas.getContext('2d');\n  var W = 0, H = 0, DPR = 1;\n\n  function resize(){\n    var r = canvas.getBoundingClientRect();\n    DPR = Math.min(2, window.devicePixelRatio || 1);\n    W = Math.max(1, Math.round(r.width));\n    H = Math.max(1, Math.round(r.height));\n    canvas.width = Math.round(W * DPR);\n    canvas.height = Math.round(H * DPR);\n    ctx.setTransform(DPR, 0, 0, DPR, 0, 0);\n  }\n  window.addEventListener('resize', resize);\n  resize();\n  ...\n})();\n```\n\nNote: `getBoundingClientRect` on a canvas with CSS size. Good.\n\nParticles:\n\n```js\nvar flames = [];\nvar embers = [];\nvar sparks = [];\n\nfunction rand(a,b){ return a + Math.random()*(b-a); }\n\nfunction spawnFlame(){\n  var baseY = H * 0.92;\n  var spread = W * 0.30;\n  var x = W/2 + rand(-spread, spread) * (0.4 + 0.6*Math.random());\n  ...\n}\n```\n\nHmm, let me design flame particles as rising blobs.\n\nFlame particle:\n- x, y (start near base)\n- vx small, vy upward speed\n- r radius\n- life, maxLife\n- seed for wobble\n\nUpdate:\n```\np.life += dt;\nvar t = p.life / p.maxLife;\np.y -= p.vy * dt;\np.x += Math.sin(p.life * p.wobbleFreq + p.seed) * p.wobbleAmp * dt;\np.r = p.r0 * (1 - t*0.7) * (1 + 0.3*Math.sin(...));\n```\n\nDraw with radial gradient:\ncolor stops based on t:\n- t<0.25: white-yellow core\n- mid: orange\n- late: red, fading alpha\n\nUse `ctx.globalCompositeOperation = 'lighter'`.\n\nLet me define a color function:\n```\nfunction flameColor(t, a){\n  // t 0..1\n  var r, g, b;\n  if(t < 0.3){ r=255; g=255 - 60*t/0.3; b=180 - 180*t/0.3; }  // white->yellow\n  ...\n}\n```\nSimpler: interpolate through stops:\nstops = [\n [0.0, 255, 255, 220],\n [0.25, 255, 230, 120],\n [0.5, 255, 160, 40],\n [0.75, 230, 80, 20],\n [1.0, 120, 20, 10]\n]\nalpha = (1-t)^1.5 * baseAlpha.\n\nLet me write a lerp over stops.\n\nEmbers: small particles, spawn at base, rise with slight drift, flicker alpha, longer life, small radius, bright orange/yellow.\n\nAlso \"logs\": draw two or three dark ellipses/rounded rects at the base with glowing ember texture. I'll draw them each frame with a warm gradient and some glowing spots that pulse.\n\nActually, drawing logs on canvas each frame with random glowing spots would flicker too much. Let me pre-generate log shapes and ember spots once, then animate their glow intensity.\n\nLet me define logs as objects with x, y, w, h, angle, and a list of ember spots (relative positions) with phase.\n\nDraw logs: save, translate, rotate, draw rounded rect with dark brown gradient, then draw ember spots as radial gradients with pulsing alpha.\n\nThen flames drawn on top with 'lighter'.\n\nThen a big soft glow at the base.\n\nAlso draw a subtle smoke? Maybe skip or add faint dark smoke rising. Could add grey translucent blobs. Might look muddy. Let me add very subtle smoke with low alpha, drawn with 'source-over' before flames? Actually smoke above flames. Let me add faint smoke particles with low alpha grey, drawn after flames with 'source-over'. Hmm, could look bad. I'll add subtle smoke \u2014 it adds cosiness. Keep alpha very low (~0.04).\n\nLet me keep it: flames + embers + glow + logs. Maybe skip smoke to avoid muddiness. Actually a little smoke is nice. I'll add it with very low alpha and large soft blobs.\n\nLet me now think about the glow overlay in CSS: a radial gradient div with animation pulsing opacity, mix-blend-mode: screen, pointer-events none. This gives the room glow.\n\nAlso add a CSS-animated flicker on the whole scene brightness.\n\nLet me write the CSS keyframes:\n\n```css\n@keyframes flicker {\n  0%   { opacity: 0.72; }\n  12%  { opacity: 0.88; }\n  24%  { opacity: 0.66; }\n  37%  { opacity: 0.92; }\n  50%  { opacity: 0.74; }\n  63%  { opacity: 0.86; }\n  76%  { opacity: 0.68; }\n  88%  { opacity: 0.9; }\n  100% { opacity: 0.72; }\n}\n```\nApplied to .glow with `animation: flicker 2.6s ease-in-out infinite;`\n\nAnd another for the room glow:\n```css\n@keyframes roomglow {\n  0%,100% { opacity: 0.55; transform: scale(1); }\n  50% { opacity: 0.8; transform: scale(1.04); }\n}\n```\n\nGood, satisfies check 3 & 4 via CSS too.\n\nNow the canvas: I need to make sure it's sized before first draw. Use requestAnimationFrame after load, plus resize on load.\n\nPotential issue: if the canvas has zero size at first (e.g., display none), drawing fails. It won't be.\n\nLet me write the full file now.\n\nOne more consideration: the check for `//` \u2014 I should double check my final file with grep.\n\nAlso check: \"no `@import`\" \u2014 avoid.\n\nLet me write it.\n\nFor the arch firebox, I'll use border-radius with slash syntax:\n`border-radius: 46% 46% 6px 6px / 34% 34% 6px 6px;`\n\nHmm, that makes an elliptical top. Good.\n\nLet me set firebox: position absolute; left: 8%; right: 8%; top: 14%; bottom: 6%; overflow: hidden; border-radius: 50% 50% 8px 8px / 38% 38% 8px 8px;\n\nWait, with overflow hidden and border-radius, the canvas inside will be clipped. Good.\n\nBut the canvas is a rectangle; the arch clipping happens via the parent's border-radius + overflow hidden. Good.\n\nNow the frame: brick surround. Let me add an inner shadow around the firebox opening for depth.\n\nLet me write:\n\n```css\n.frame {\n  position: absolute; inset: 0;\n  border-radius: 22px 22px 10px 10px;\n  background-color: #2a1712;\n  background-image:\n    repeating-linear-gradient(0deg, rgba(0,0,0,0.55) 0 3px, rgba(0,0,0,0) 3px 30px),\n    repeating-linear-gradient(90deg, rgba(0,0,0,0.55) 0 3px, rgba(0,0,0,0) 3px 62px),\n    linear-gradient(160deg, #5a2f22 0%, #3a1d15 45%, #24110c 100%);\n  box-shadow: inset 0 0 60px rgba(0,0,0,0.8), 0 30px 60px rgba(0,0,0,0.7);\n}\n```\n\nHmm, the repeating gradients create a grid of mortar lines. With the linear gradient underneath as brick color. But bricks would all be one color. Add a subtle noise via multiple radial gradients? Could add a few random-ish radial gradients for brick variation. Let me add a couple of large soft radial gradients with slight color variation.\n\nActually, to make bricks look better, I can use a repeating pattern with offset rows. Let me do:\n\nLayer 1 (mortar): solid dark color as background-color.\nLayer 2: bricks drawn as repeating-linear-gradient in both directions with the brick color, offset.\n\nSimplest approach that looks decent:\n```css\nbackground-color: #1a0d09; /* mortar */\nbackground-image:\n  repeating-linear-gradient(90deg, #4a2418 0 58px, transparent 58px 62px),\n  repeating-linear-gradient(0deg, #4a2418 0 26px, transparent 26px 30px);\n```\nThis gives a grid of bricks 58x26 with 4px mortar. But all bricks same color. Add a third layer with a subtle gradient overlay for lighting:\n```css\n  linear-gradient(180deg, rgba(255,180,120,0.10), rgba(0,0,0,0.45))\n```\nAnd a radial highlight near the fire.\n\nFor offset rows, I can use `background-position` on the vertical lines layer... but repeating-linear-gradient with 90deg creates vertical lines; offsetting rows requires a different technique. I'll skip offset; a running bond isn't essential.\n\nActually I can do offset bricks using two layers each covering half the height... too complex. Skip.\n\nLet me add brick color variation with a few radial-gradients at fixed positions:\n```css\nradial-gradient(circle at 20% 30%, rgba(255,140,80,0.10), transparent 40%),\nradial-gradient(circle at 75% 65%, rgba(255,120,60,0.08), transparent 45%),\n```\nFine.\n\nNow the hearth: a slab at the bottom front, slightly lighter stone.\n\nLet me place .hearth: position absolute; left: -4%; right: -4%; bottom: -3%; height: 9%; background: linear-gradient(#3a2a22, #1a100c); border-radius: 6px; box-shadow: 0 10px 30px rgba(0,0,0,0.8);\n\nHmm, but the firebox bottom is at 6% from bottom, so the hearth overlaps. Fine.\n\nActually let me reconsider the composition. Let me make the firebox bottom flush with the frame bottom minus a hearth strip.\n\nLet me just do:\n- frame: full\n- firebox: left 9%, right 9%, top 13%, bottom 12%\n- hearth: left 2%, right 2%, bottom 2%, height 12%\n\nThen the firebox sits above the hearth. Good.\n\nNow the canvas fills the firebox. The base of the fire (logs) at the bottom of the canvas.\n\nLet me write the JS now in detail.\n\n```js\n(function(){\n  'use strict';\n  var canvas = document.getElementById('fire');\n  var ctx = canvas.getContext('2d');\n  var W = 300, H = 200, DPR = 1;\n\n  function resize(){\n    var rect = canvas.getBoundingClientRect();\n    var w = Math.max(1, Math.round(rect.width));\n    var h = Math.max(1, Math.round(rect.height));\n    DPR = Math.min(2, window.devicePixelRatio || 1);\n    W = w; H = h;\n    canvas.width = Math.round(w * DPR);\n    canvas.height = Math.round(h * DPR);\n    ctx.setTransform(DPR, 0, 0, DPR, 0, 0);\n  }\n```\n\nNote: after setting canvas.width, the transform resets, so setTransform after. Good.\n\nParticles arrays.\n\n```js\n  var flames = [], embers = [], smoke = [];\n  var t0 = 0;\n\n  function rnd(a, b){ return a + Math.random() * (b - a); }\n\n  var STOPS = [\n    [0.00, 255, 255, 235],\n    [0.18, 255, 240, 170],\n    [0.38, 255, 190, 70],\n    [0.60, 255, 120, 30],\n    [0.80, 200, 55, 15],\n    [1.00, 90, 15, 8]\n  ];\n\n  function flameColor(t){\n    t = t < 0 ? 0 : (t > 1 ? 1 : t);\n    for(var i = 1; i < STOPS.length; i++){\n      if(t <= STOPS[i][0]){\n        var a = STOPS[i-1], b = STOPS[i];\n        var f = (t - a[0]) / (b[0] - a[0]);\n        return [\n          a[1] + (b[1]-a[1])*f,\n          a[2] + (b[2]-a[2])*f,\n          a[3] + (b[3]-a[3])*f\n        ];\n      }\n    }\n    var l = STOPS[STOPS.length-1];\n    return [l[1], l[2], l[3]];\n  }\n```\n\nFlame spawn:\n\n```js\n  function spawnFlame(){\n    var baseY = H * 0.94;\n    var cx = W * 0.5;\n    var spread = W * 0.26;\n    var x = cx + rnd(-spread, spread);\n    // bias toward center\n    x = cx + (x - cx) * (0.35 + 0.65 * Math.random());\n    var life = rnd(0.55, 1.15);\n    flames.push({\n      x: x,\n      y: baseY + rnd(-6, 6),\n      vx: rnd(-14, 14),\n      vy: rnd(70, 150) * (H / 260),\n      r0: rnd(10, 26) * (W / 300),\n      life: 0,\n      maxLife: life,\n      seed: Math.random() * 6.283,\n      wob: rnd(3, 8),\n      amp: rnd(6, 22)\n    });\n  }\n```\n\nHmm, the flame should rise and shrink. Let me tune.\n\nUpdate:\n\n```js\n  function update(dt){\n    // spawn\n    var rate = 90; // per second\n    spawnAcc += rate * dt;\n    while(spawnAcc >= 1){ spawnAcc -= 1; spawnFlame(); }\n    ...\n  }\n```\n\nActually let me use a spawn accumulator.\n\nEmbers: spawn rate ~ 18/s.\n\nSmoke: ~ 6/s.\n\nUpdate flames:\n```js\n    for(var i = flames.length - 1; i >= 0; i--){\n      var p = flames[i];\n      p.life += dt;\n      if(p.life >= p.maxLife){ flames.splice(i, 1); continue; }\n      var t = p.life / p.maxLife;\n      p.y -= p.vy * dt * (1 - 0.35 * t);\n      p.x += p.vx * dt + Math.sin(p.life * p.wob + p.seed) * p.amp * dt;\n      p.vx *= (1 - 1.2 * dt);\n    }\n```\n\nDraw flames:\n```js\n    ctx.globalCompositeOperation = 'lighter';\n    for(...){\n      var t = p.life / p.maxLife;\n      var col = flameColor(t);\n      var r = p.r0 * (1 - 0.55 * t) * (1 + 0.25 * Math.sin(p.life * 9 + p.seed));\n      if(r < 0.5) continue;\n      var a = Math.pow(1 - t, 1.6) * 0.55;\n      var g = ctx.createRadialGradient(p.x, p.y, 0, p.x, p.y, r);\n      g.addColorStop(0, 'rgba(' + (col[0]|0) + ',' + (col[1]|0) + ',' + (col[2]|0) + ',' + a.toFixed(3) + ')');\n      g.addColorStop(0.5, 'rgba(' + (col[0]|0) + ',' + (col[1]|0) + ',' + (col[2]|0) + ',' + (a*0.45).toFixed(3) + ')');\n      g.addColorStop(1, 'rgba(' + (col[0]|0) + ',' + (col[1]|0) + ',' + (col[2]|0) + ',0)');\n      ctx.fillStyle = g;\n      ctx.beginPath();\n      ctx.arc(p.x, p.y, r, 0, 6.2832);\n      ctx.fill();\n    }\n```\n\nCreating gradients per particle per frame is expensive but with ~150 particles it's OK at 60fps. Might be heavy. Alternative: pre-render a few sprite canvases (e.g., 8 color variants) and drawImage scaled. That's much faster. Let me do sprite-based rendering.\n\nPre-render sprites: for each of N=10 color steps, create an offscreen canvas of size 64x64 with a radial gradient from color (alpha 1) to transparent. Then draw with globalAlpha and scaling.\n\nThat's efficient and looks good.\n\nLet me do that.\n\n```js\n  var SPRITES = [];\n  function makeSprites(){\n    SPRITES = [];\n    var N = 12;\n    for(var i = 0; i < N; i++){\n      var t = i / (N - 1);\n      var col = flameColor(t);\n      var s = document.createElement('canvas');\n      s.width = 64; s.height = 64;\n      var c = s.getContext('2d');\n      var g = c.createRadialGradient(32, 32, 0, 32, 32, 32);\n      g.addColorStop(0, 'rgba(' + (col[0]|0) + ',' + (col[1]|0) + ',' + (col[2]|0) + ',1)');\n      g.addColorStop(0.35, 'rgba(' + (col[0]|0) + ',' + (col[1]|0) + ',' + (col[2]|0) + ',0.55)');\n      g.addColorStop(0.7, 'rgba(' + (col[0]|0) + ',' + (col[1]|0) + ',' + (col[2]|0) + ',0.16)');\n      g.addColorStop(1, 'rgba(' + (col[0]|0) + ',' + (col[1]|0) + ',' + (col[2]|0) + ',0)');\n      c.fillStyle = g;\n      c.fillRect(0, 0, 64, 64);\n      SPRITES.push(s);\n    }\n  }\n```\n\nThen draw:\n```js\n      var idx = Math.min(N-1, Math.floor(t * N));\n      var spr = SPRITES[idx];\n      var r = ...;\n      ctx.globalAlpha = a;\n      ctx.drawImage(spr, p.x - r, p.y - r, r*2, r*2);\n```\n\nWith globalCompositeOperation 'lighter'. \n\nNote: `document.createElement('canvas')` \u2014 fine, no external request.\n\nNow logs. Let me define logs once (in normalized coords relative to W,H) and draw each frame.\n\n```js\n  var logs = [];\n  function makeLogs(){\n    logs = [\n      { x: 0.50, y: 0.93, w: 0.62, h: 0.10, a: -0.06, tone: 0 },\n      { x: 0.44, y: 0.88, w: 0.50, h: 0.09, a: 0.10, tone: 1 },\n      { x: 0.58, y: 0.86, w: 0.40, h: 0.08, a: -0.16, tone: 2 }\n    ];\n    // ember spots on logs\n    for(var i = 0; i < logs.length; i++){\n      var L = logs[i];\n      L.spots = [];\n      var n = 5 + (i * 2);\n      for(var j = 0; j < n; j++){\n        L.spots.push({\n          u: rnd(-0.42, 0.42),\n          v: rnd(-0.3, 0.3),\n          r: rnd(0.05, 0.16),\n          ph: Math.random() * 6.283,\n          sp: rnd(1.2, 3.4)\n        });\n      }\n    }\n  }\n```\n\nDraw logs:\n```js\n  function drawLogs(time){\n    for(var i = 0; i < logs.length; i++){\n      var L = logs[i];\n      var cx = L.x * W, cy = L.y * H;\n      var w = L.w * W, h = L.h * H;\n      ctx.save();\n      ctx.translate(cx, cy);\n      ctx.rotate(L.a);\n      // body\n      var g = ctx.createLinearGradient(0, -h/2, 0, h/2);\n      g.addColorStop(0, '#3a2418');\n      g.addColorStop(0.45, '#241209');\n      g.addColorStop(1, '#120806');\n      ctx.fillStyle = g;\n      roundRect(ctx, -w/2, -h/2, w, h, h/2);\n      ctx.fill();\n      // ember spots\n      ctx.globalCompositeOperation = 'lighter';\n      for(var j = 0; j < L.spots.length; j++){\n        var s = L.spots[j];\n        var pulse = 0.45 + 0.55 * (0.5 + 0.5 * Math.sin(time * s.sp + s.ph));\n        var rr = s.r * h * 1.6;\n        var sx = s.u * w, sy = s.v * h;\n        var sg = ctx.createRadialGradient(sx, sy, 0, sx, sy, rr);\n        sg.addColorStop(0, 'rgba(255,190,90,' + (0.85 * pulse).toFixed(3) + ')');\n        sg.addColorStop(0.4, 'rgba(255,110,30,' + (0.45 * pulse).toFixed(3) + ')');\n        sg.addColorStop(1, 'rgba(120,20,0,0)');\n        ctx.fillStyle = sg;\n        ctx.beginPath();\n        ctx.arc(sx, sy, rr, 0, 6.2832);\n        ctx.fill();\n      }\n      ctx.restore();\n    }\n  }\n```\n\nCreating gradients per spot per frame: 3 logs * ~7 spots = 21 gradients/frame. Acceptable.\n\nActually, I could pre-render ember sprites too. Let me pre-render one ember sprite and tint via globalAlpha... but color varies. Just use one orange sprite. Let me pre-render an ember sprite (orange radial) and draw with alpha. Simpler and faster.\n\nLet me make a generic sprite maker: `makeGlowSprite(r,g,b)` returns canvas.\n\nI'll create:\n- flame sprites (12)\n- ember sprite (orange-yellow)\n- smoke sprite (grey)\n\nThen draw everything with drawImage. \n\nroundRect helper: use ctx.roundRect if available, else manual. Chrome supports ctx.roundRect. But to be safe, write manual.\n\nNow the base glow: a big radial gradient at the bottom center, drawn with 'lighter', pulsing.\n\nAlso draw a warm light on the back wall of the firebox (the canvas background). Actually the canvas is transparent over the firebox's dark background. Let me draw a subtle warm radial at the bottom of the canvas each frame (with 'source-over' or 'lighter').\n\nLet me structure the draw:\n\n```js\n  function draw(time){\n    ctx.setTransform(DPR, 0, 0, DPR, 0, 0);\n    ctx.clearRect(0, 0, W, H);\n\n    // back wall warm glow\n    ctx.globalCompositeOperation = 'source-over';\n    var bg = ctx.createRadialGradient(W*0.5, H*1.02, 0, W*0.5, H*1.02, H*0.95);\n    bg.addColorStop(0, 'rgba(120,40,10,0.55)');\n    bg.addColorStop(0.5, 'rgba(60,18,6,0.28)');\n    bg.addColorStop(1, 'rgba(0,0,0,0)');\n    ctx.fillStyle = bg;\n    ctx.fillRect(0, 0, W, H);\n\n    // smoke (behind flames? or above) -> draw smoke first with source-over\n    drawSmoke();\n\n    // logs\n    drawLogs(time);\n\n    // flames\n    ctx.globalCompositeOperation = 'lighter';\n    drawFlames();\n\n    // embers\n    drawEmbers();\n\n    // base glow\n    ...\n    ctx.globalAlpha = 1;\n    ctx.globalCompositeOperation = 'source-over';\n  }\n```\n\nHmm, smoke should be above flames visually. But smoke drawn with source-over after flames would dim them. With low alpha it's fine. Let me draw smoke after flames with very low alpha.\n\nActually, let me skip smoke to keep it clean and avoid muddiness. Or include it subtly. I'll include it \u2014 it adds cosiness. Low alpha 0.05, grey, large, rising slowly, drawn after flames with 'source-over'.\n\nHmm, but smoke over flames with source-over grey will grey out the flames. With alpha 0.05 it's negligible. OK.\n\nActually, let me draw smoke behind the flames (before), so it appears as haze in the firebox. That's safer. Smoke rising behind flames. Fine.\n\nLet me finalize.\n\nEmber particles:\n```js\n  function spawnEmber(){\n    var x = W * 0.5 + rnd(-W*0.22, W*0.22);\n    embers.push({\n      x: x,\n      y: H * 0.92 + rnd(-4, 4),\n      vx: rnd(-18, 18),\n      vy: rnd(45, 110) * (H/260),\n      r: rnd(1.2, 3.2) * (W/300),\n      life: 0,\n      maxLife: rnd(1.4, 3.2),\n      seed: Math.random()*6.283,\n      wob: rnd(2, 6),\n      amp: rnd(10, 40)\n    });\n  }\n```\n\nUpdate: y -= vy*dt; x += vx*dt + sin(...)*amp*dt; vy *= (1 - 0.3*dt) maybe; alpha fades in then out.\n\nDraw embers with 'lighter', small sprite, alpha = flicker * fade.\n\nfade = sin(pi * t) maybe, or (1-t) with quick fade in.\n\nLet me use: a = Math.min(1, t*6) * Math.pow(1-t, 1.2) * (0.6 + 0.4*Math.sin(time*20 + seed)).\n\nGood.\n\nNow the main loop and time.\n\n```js\n  var last = 0, acc = 0, spawnAcc = 0, emberAcc = 0, smokeAcc = 0;\n  var clock = 0;\n\n  function step(now){\n    if(!last) last = now;\n    var dt = (now - last) / 1000;\n    last = now;\n    if(dt > 0.08) dt = 0.08;\n    if(dt < 0) dt = 0;\n    clock += dt;\n    update(dt);\n    draw(clock);\n  }\n```\n\nWait, `clock` used for pulsing. Fine.\n\nrAF loop:\n```js\n  function raf(now){\n    step(now);\n    requestAnimationFrame(raf);\n  }\n  requestAnimationFrame(raf);\n```\n\nFallback interval:\n```js\n  setInterval(function(){\n    var now = performance.now();\n    if(now - last > 120){ step(now); }\n  }, 60);\n```\n\nHmm, if rAF works at 60fps, `now - last` is ~16ms, so interval does nothing. If rAF is throttled, interval drives. Good.\n\nBut careful: `last` is set inside step. Initially last=0, so first interval call would step. Fine.\n\nAlso need to handle resize: on resize, re-init logs? Logs are normalized so they scale. Sprites don't depend on size. Good. Just call resize() and redraw.\n\nAlso, `resize()` should be called on load and on window resize. And after fonts/layout. Use `window.addEventListener('load', ...)` too.\n\nPotential issue: canvas getBoundingClientRect at script execution time (script at end of body) \u2014 layout should be computed. Should be fine.\n\nLet me also add a `ResizeObserver`? Not necessary.\n\nNow, one concern: the check \"page_animates\" screenshots at 1.5s and 2.5s. If the animation is running, they differ. Good.\n\nAnother concern: check 4 browser part \u2014 page must still change between ~6s and ~7s. Continuous animation ensures that.\n\nNow let me also double-check: no `//` anywhere. In my JS I use `/* */`? I'll avoid comments entirely. Let me make sure no `//` appears. Things like `'rgba(...)'` no. Division `/` single. `6.2832` fine.\n\nWait: `Math.PI * 2` \u2014 I'll use 6.2832 constant.\n\nAlso in CSS: `background: url()` none. `inset: 0` fine.\n\nHmm, `border-radius: 50% 50% 8px 8px / 38% 38% 8px 8px;` \u2014 contains `/` single. Fine.\n\nLet me also avoid the string `//` in any attribute.\n\nAlso, the check mentions `data` attribute \u2014 avoid `data-*`? It says no URLs in `data` attribute. I won't use data attributes with URLs. Fine.\n\nLet me now write the file.\n\nAlso add `<title>Cosy Fireplace</title>` \u2014 contains \"Fireplace\". Good.\n\nid=\"fireplace\" on the main container.\n\nLet me write out the complete HTML.\n\nLet me be careful about the `roundRect` helper.\n\n```js\n  function roundRect(c, x, y, w, h, r){\n    if(r > h/2) r = h/2;\n    if(r > w/2) r = w/2;\n    c.beginPath();\n    c.moveTo(x + r, y);\n    c.lineTo(x + w - r, y);\n    c.quadraticCurveTo(x + w, y, x + w, y + r);\n    c.lineTo(x + w, y + h - r);\n    c.quadraticCurveTo(x + w, y + h, x + w - r, y + h);\n    c.lineTo(x + r, y + h);\n    c.quadraticCurveTo(x, y + h, x, y + h - r);\n    c.lineTo(x, y + r);\n    c.quadraticCurveTo(x, y, x + r, y);\n    c.closePath();\n  }\n```\n\nGood.\n\nNow let me write everything.\n\nLet me also add a subtle \"sparks\" that occasionally pop. Embers cover that.\n\nLet me write the file now.\n\nOne more: the glow div with mix-blend-mode screen over the canvas \u2014 it will brighten. Let me put the glow div inside the firebox, absolutely positioned, covering the lower area, with a radial gradient of warm orange, animated opacity. mix-blend-mode: screen.\n\nAlso a room-wide glow behind the fireplace: a big radial gradient on the body background that pulses. I'll add a `.roomglow` div fixed behind everything with animation.\n\nLet me write.\n\nAlso, to make the scene look nicer, add a vignette overlay.\n\nLet me write the final HTML.\n\nRegarding size: well under 100KB.\n\nLet me write it.\n\nI'll write the file with the write_file tool.\n\nLet me carefully compose.\n\n```html\n<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"utf-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">\n<title>Cosy Fireplace</title>\n<style>\n  :root {\n    --warm: #ff9a3c;\n  }\n  * { box-sizing: border-box; }\n  html, body {\n    margin: 0;\n    padding: 0;\n    height: 100%;\n    background: #070403;\n    overflow: hidden;\n    font-family: Georgia, 'Times New Roman', serif;\n  }\n  body {\n    display: flex;\n    align-items: center;\n    justify-content: center;\n  }\n  .roomglow {\n    position: fixed;\n    left: 50%;\n    top: 62%;\n    width: 140vmin;\n    height: 140vmin;\n    margin-left: -70vmin;\n    margin-top: -70vmin;\n    border-radius: 50%;\n    background: radial-gradient(circle, rgba(255,140,50,0.30) 0%, rgba(255,90,20,0.14) 32%, rgba(120,30,0,0.05) 55%, rgba(0,0,0,0) 72%);\n    pointer-events: none;\n    animation: roompulse 4.2s ease-in-out infinite;\n    z-index: 0;\n  }\n  @keyframes roompulse {\n    0%   { opacity: 0.62; transform: scale(1); }\n    22%  { opacity: 0.86; transform: scale(1.03); }\n    47%  { opacity: 0.58; transform: scale(0.99); }\n    71%  { opacity: 0.9;  transform: scale(1.04); }\n    100% { opacity: 0.62; transform: scale(1); }\n  }\n  ...\n</style>\n```\n\nHmm, `transform: scale()` on a fixed element with margins \u2014 fine.\n\nNow #fireplace:\n\n```css\n  #fireplace {\n    position: relative;\n    width: min(88vw, 660px);\n    height: min(78vh, 520px);\n    z-index: 1;\n    filter: drop-shadow(0 24px 40px rgba(0,0,0,0.75));\n  }\n```\n\nHmm, `min()` with vw/vh. In 800x600: 88vw = 704, so 660. 78vh = 468. So 660x468. Good.\n\nActually let me use aspect-ratio to keep proportions. `width: min(88vw, 660px); aspect-ratio: 660 / 520;` and height auto. But then height might exceed 78vh. Let me use `height: min(78vh, 520px); width: auto; aspect-ratio: 660/520;` Hmm, with width auto and aspect-ratio, width derives from height. In 800x600: height = min(468, 520) = 468, width = 468 * 660/520 = 594. Fits in 800. Good.\n\nLet me use that.\n\nActually simpler and safe: \n```css\n#fireplace {\n  position: relative;\n  width: min(86vw, 640px);\n  height: min(76vh, 500px);\n}\n```\nIn 800x600: 640 x 456. Fine. Aspect 1.4. Good enough.\n\nLet me go with explicit width/height.\n\nNow the frame and firebox.\n\n```css\n  .frame {\n    position: absolute;\n    inset: 0;\n    border-radius: 26px 26px 12px 12px;\n    background-color: #150a07;\n    background-image:\n      repeating-linear-gradient(90deg, rgba(0,0,0,0.85) 0 4px, rgba(0,0,0,0) 4px 62px),\n      repeating-linear-gradient(0deg, rgba(0,0,0,0.85) 0 4px, rgba(0,0,0,0) 4px 30px),\n      radial-gradient(circle at 50% 118%, rgba(255,150,70,0.30), rgba(0,0,0,0) 55%),\n      linear-gradient(165deg, #6b3a26 0%, #4a2418 38%, #2c140d 72%, #1a0b07 100%);\n    box-shadow:\n      inset 0 0 0 2px rgba(0,0,0,0.5),\n      inset 0 0 70px rgba(0,0,0,0.85),\n      0 26px 50px rgba(0,0,0,0.8);\n  }\n```\n\nWait, the repeating gradients with rgba(0,0,0,0.85) create dark mortar lines over the brick gradient. The brick color comes from the linear-gradient underneath. Good.\n\nHmm, but the radial warm glow at the bottom is under the mortar lines. Fine.\n\nAdd a brick highlight layer:\n```css\n      repeating-linear-gradient(90deg, rgba(255,190,140,0.05) 0 58px, rgba(0,0,0,0) 58px 62px),\n```\nMeh. Skip.\n\nNow the firebox:\n\n```css\n  .firebox {\n    position: absolute;\n    left: 9%;\n    right: 9%;\n    top: 12%;\n    bottom: 13%;\n    border-radius: 50% 50% 10px 10px / 34% 34% 10px 10px;\n    overflow: hidden;\n    background: radial-gradient(ellipse at 50% 100%, #2a0f06 0%, #140703 45%, #050201 100%);\n    box-shadow:\n      inset 0 0 40px rgba(0,0,0,0.95),\n      inset 0 14px 30px rgba(0,0,0,0.9),\n      0 0 0 3px rgba(0,0,0,0.55);\n  }\n```\n\nHmm, `box-shadow` outside with overflow hidden \u2014 the outer shadow ring is drawn outside the element, fine.\n\nWait, `overflow: hidden` clips children to the border-radius. Good.\n\nCanvas:\n```css\n  #fire {\n    position: absolute;\n    inset: 0;\n    width: 100%;\n    height: 100%;\n    display: block;\n  }\n```\n\nGlow overlay inside firebox:\n```css\n  .glow {\n    position: absolute;\n    left: -10%;\n    right: -10%;\n    bottom: -20%;\n    height: 90%;\n    background: radial-gradient(ellipse at 50% 100%, rgba(255,170,80,0.55) 0%, rgba(255,110,30,0.28) 35%, rgba(180,50,0,0.08) 60%, rgba(0,0,0,0) 78%);\n    mix-blend-mode: screen;\n    pointer-events: none;\n    animation: flicker 2.7s ease-in-out infinite;\n  }\n  @keyframes flicker {\n    0%   { opacity: 0.70; }\n    9%   { opacity: 0.92; }\n    18%  { opacity: 0.62; }\n    27%  { opacity: 0.86; }\n    38%  { opacity: 0.58; }\n    49%  { opacity: 0.95; }\n    58%  { opacity: 0.68; }\n    69%  { opacity: 0.88; }\n    79%  { opacity: 0.60; }\n    90%  { opacity: 0.90; }\n    100% { opacity: 0.70; }\n  }\n```\n\nHearth:\n```css\n  .hearth {\n    position: absolute;\n    left: 1%;\n    right: 1%;\n    bottom: 1%;\n    height: 13%;\n    border-radius: 8px;\n    background: linear-gradient(180deg, #4a2c1e 0%, #2a1610 40%, #140a06 100%);\n    box-shadow: 0 -2px 0 rgba(255,170,90,0.10), 0 14px 30px rgba(0,0,0,0.85), inset 0 2px 6px rgba(255,180,110,0.10);\n  }\n```\n\nHmm, the hearth should be in front of the firebox bottom. Since firebox bottom is at 13% and hearth top is at 1%+13% = 14% from bottom... wait hearth bottom:1%, height 13% \u2192 top at 14% from bottom. Firebox bottom at 13%. So hearth top (14%) is above firebox bottom (13%)? No: bottom:13% means the firebox's bottom edge is 13% from the container bottom. Hearth occupies from 1% to 14% from bottom. So hearth top edge at 14% is above firebox bottom edge at 13%. So the hearth overlaps the firebox's bottom 1%. Good, it sits in front.\n\nOrder in DOM: frame, firebox, hearth. Hearth after firebox \u2192 drawn on top. Good.\n\nAlso add a mantel? Optional. Let me add a subtle top mantel shelf for cosiness. Maybe skip.\n\nLet me add a small \"andiron\" or just keep it.\n\nNow let me write the JS.\n\nI'll write it carefully.\n\nLet me now produce the final file.\n\nAlso: I should double check there's no `//` in the file. Let me grep after writing.\n\nLet me write it.\n\nFor the smoke sprite, grey radial.\n\nLet me write the code.\n\n```js\n(function () {\n  'use strict';\n\n  var canvas = document.getElementById('fire');\n  var ctx = canvas.getContext('2d');\n  var W = 320, H = 240, DPR = 1;\n\n  function rnd(a, b) { return a + Math.random() * (b - a); }\n\n  var STOPS = [\n    [0.00, 255, 255, 240],\n    [0.16, 255, 244, 190],\n    [0.34, 255, 205, 95],\n    [0.54, 255, 140, 40],\n    [0.74, 214, 70, 18],\n    [1.00, 96, 18, 8]\n  ];\n\n  function flameColor(t) {\n    if (t < 0) t = 0;\n    if (t > 1) t = 1;\n    for (var i = 1; i < STOPS.length; i++) {\n      if (t <= STOPS[i][0]) {\n        var a = STOPS[i - 1], b = STOPS[i];\n        var f = (t - a[0]) / (b[0] - a[0]);\n        return [a[1] + (b[1] - a[1]) * f, a[2] + (b[2] - a[2]) * f, a[3] + (b[3] - a[3]) * f];\n      }\n    }\n    var l = STOPS[STOPS.length - 1];\n    return [l[1], l[2], l[3]];\n  }\n\n  function glowSprite(r, g, b, soft) {\n    var s = document.createElement('canvas');\n    s.width = 64;\n    s.height = 64;\n    var c = s.getContext('2d');\n    var grd = c.createRadialGradient(32, 32, 0, 32, 32, 32);\n    grd.addColorStop(0, 'rgba(' + r + ',' + g + ',' + b + ',1)');\n    grd.addColorStop(0.30, 'rgba(' + r + ',' + g + ',' + b + ',' + (soft ? 0.42 : 0.62) + ')');\n    grd.addColorStop(0.62, 'rgba(' + r + ',' + g + ',' + b + ',' + (soft ? 0.12 : 0.20) + ')');\n    grd.addColorStop(1, 'rgba(' + r + ',' + g + ',' + b + ',0)');\n    c.fillStyle = grd;\n    c.fillRect(0, 0, 64, 64);\n    return s;\n  }\n\n  var FLAME_SPRITES = [];\n  var EMBER_SPRITE = null;\n  var SMOKE_SPRITE = null;\n\n  function buildSprites() {\n    FLAME_SPRITES = [];\n    var N = 14;\n    for (var i = 0; i < N; i++) {\n      var col = flameColor(i / (N - 1));\n      FLAME_SPRITES.push(glowSprite(col[0] | 0, col[1] | 0, col[2] | 0, false));\n    }\n    EMBER_SPRITE = glowSprite(255, 190, 90, false);\n    SMOKE_SPRITE = glowSprite(120, 110, 105, true);\n  }\n```\n\nHmm, smoke sprite with alpha 1 at center is too strong; I'll draw with low globalAlpha.\n\nNow particles.\n\n```js\n  var flames = [];\n  var embers = [];\n  var smoke = [];\n  var logs = [];\n\n  function makeLogs() {\n    logs = [\n      { x: 0.50, y: 0.94, w: 0.66, h: 0.11, a: -0.05, tone: 0 },\n      { x: 0.43, y: 0.885, w: 0.52, h: 0.095, a: 0.11, tone: 1 },\n      { x: 0.59, y: 0.865, w: 0.42, h: 0.085, a: -0.17, tone: 2 }\n    ];\n    for (var i = 0; i < logs.length; i++) {\n      var L = logs[i];\n      L.spots = [];\n      var n = 6 + i * 2;\n      for (var j = 0; j < n; j++) {\n        L.spots.push({\n          u: rnd(-0.40, 0.40),\n          v: rnd(-0.28, 0.28),\n          r: rnd(0.06, 0.17),\n          ph: Math.random() * 6.2832,\n          sp: rnd(1.1, 3.6)\n        });\n      }\n    }\n  }\n```\n\nSpawn functions.\n\n```js\n  function spawnFlame() {\n    var cx = W * 0.5;\n    var spread = W * 0.30;\n    var x = cx + rnd(-spread, spread) * (0.30 + 0.70 * Math.random());\n    flames.push({\n      x: x,\n      y: H * 0.93 + rnd(-5, 5),\n      vx: rnd(-16, 16),\n      vy: rnd(0.30, 0.62) * H,\n      r0: rnd(0.030, 0.085) * W,\n      life: 0,\n      maxLife: rnd(0.55, 1.15),\n      seed: Math.random() * 6.2832,\n      wob: rnd(3, 9),\n      amp: rnd(0.02, 0.09) * W\n    });\n  }\n```\n\nvy in units of H per second: 0.30*H to 0.62*H. For H=240, that's 72-149 px/s. Over 1s life, rises 72-149px. Canvas height 240. Good.\n\nr0: 0.03*W to 0.085*W \u2192 for W=320: 9.6 to 27. Good.\n\namp: 0.02*W to 0.09*W \u2192 6.4 to 28.8 px/s lateral wobble. Good.\n\n```js\n  function spawnEmber() {\n    embers.push({\n      x: W * 0.5 + rnd(-W * 0.24, W * 0.24),\n      y: H * 0.92 + rnd(-4, 4),\n      vx: rnd(-20, 20),\n      vy: rnd(0.18, 0.46) * H,\n      r: rnd(0.004, 0.012) * W,\n      life: 0,\n      maxLife: rnd(1.3, 3.0),\n      seed: Math.random() * 6.2832,\n      wob: rnd(2, 7),\n      amp: rnd(0.03, 0.13) * W\n    });\n  }\n\n  function spawnSmoke() {\n    smoke.push({\n      x: W * 0.5 + rnd(-W * 0.16, W * 0.16),\n      y: H * 0.80 + rnd(-6, 6),\n      vx: rnd(-10, 10),\n      vy: rnd(0.10, 0.22) * H,\n      r: rnd(0.10, 0.22) * W,\n      life: 0,\n      maxLife: rnd(2.2, 4.0),\n      seed: Math.random() * 6.2832,\n      wob: rnd(1, 3),\n      amp: rnd(0.02, 0.07) * W\n    });\n  }\n```\n\nUpdate:\n\n```js\n  var accFlame = 0, accEmber = 0, accSmoke = 0;\n\n  function update(dt) {\n    accFlame += 110 * dt;\n    while (accFlame >= 1) { accFlame -= 1; spawnFlame(); }\n    accEmber += 16 * dt;\n    while (accEmber >= 1) { accEmber -= 1; spawnEmber(); }\n    accSmoke += 5 * dt;\n    while (accSmoke >= 1) { accSmoke -= 1; spawnSmoke(); }\n\n    var i, p, t;\n    for (i = flames.length - 1; i >= 0; i--) {\n      p = flames[i];\n      p.life += dt;\n      if (p.life >= p.maxLife) { flames.splice(i, 1); continue; }\n      t = p.life / p.maxLife;\n      p.y -= p.vy * dt * (1 - 0.30 * t);\n      p.x += p.vx * dt + Math.sin(p.life * p.wob + p.seed) * p.amp * dt;\n      p.vx *= (1 - 1.4 * dt);\n    }\n    for (i = embers.length - 1; i >= 0; i--) {\n      p = embers[i];\n      p.life += dt;\n      if (p.life >= p.maxLife) { embers.splice(i, 1); continue; }\n      t = p.life / p.maxLife;\n      p.y -= p.vy * dt;\n      p.x += p.vx * dt + Math.sin(p.life * p.wob + p.seed) * p.amp * dt;\n      p.vx *= (1 - 0.8 * dt);\n      p.vy *= (1 - 0.25 * dt);\n    }\n    for (i = smoke.length - 1; i >= 0; i--) {\n      p = smoke[i];\n      p.life += dt;\n      if (p.life >= p.maxLife) { smoke.splice(i, 1); continue; }\n      p.y -= p.vy * dt;\n      p.x += p.vx * dt + Math.sin(p.life * p.wob + p.seed) * p.amp * dt;\n      p.vx *= (1 - 0.6 * dt);\n    }\n  }\n```\n\nCap particle counts to avoid runaway: if flames.length > 400, skip spawning. Let me add guards in spawn functions or in update. Add: `if (flames.length < 500) { accFlame += ... }`. Simpler: in the while loop, break if length > 500.\n\nLet me add a check at the start of update: if arrays too long, trim.\n\nActually with 110/s spawn and max life 1.15s, max ~127 flames. Fine. Embers 16/s * 3s = 48. Smoke 5/s * 4s = 20. All fine.\n\nDraw functions.\n\n```js\n  function drawFlames() {\n    var N = FLAME_SPRITES.length;\n    ctx.globalCompositeOperation = 'lighter';\n    for (var i = 0; i < flames.length; i++) {\n      var p = flames[i];\n      var t = p.life / p.maxLife;\n      var idx = Math.floor(t * N);\n      if (idx > N - 1) idx = N - 1;\n      var r = p.r0 * (1 - 0.55 * t) * (1 + 0.22 * Math.sin(p.life * 9 + p.seed));\n      if (r < 0.6) continue;\n      var a = Math.pow(1 - t, 1.5) * 0.62;\n      ctx.globalAlpha = a;\n      ctx.drawImage(FLAME_SPRITES[idx], p.x - r, p.y - r, r * 2, r * 2);\n    }\n    ctx.globalAlpha = 1;\n  }\n```\n\nHmm, the flame sprite index based on t: young particles use bright sprite (index 0), old use dark red. Good.\n\nBut the flame shape: a radial blob. Stacking many gives a flame-like mass. Should look decent.\n\nTo make it more flame-like, I could stretch vertically: drawImage with height > width. Let me make flames taller than wide: `ctx.drawImage(spr, p.x - r*0.8, p.y - r*1.5, r*1.6, r*3.0)`. That gives vertical elongation. Nice.\n\nLet me use rx = r*0.85, ry = r*1.7.\n\n```js\n      var rx = r * 0.85, ry = r * 1.7;\n      ctx.drawImage(FLAME_SPRITES[idx], p.x - rx, p.y - ry, rx * 2, ry * 2);\n```\n\nGood.\n\nEmbers:\n```js\n  function drawEmbers(time) {\n    ctx.globalCompositeOperation = 'lighter';\n    for (var i = 0; i < embers.length; i++) {\n      var p = embers[i];\n      var t = p.life / p.maxLife;\n      var fade = Math.min(1, t * 7) * Math.pow(1 - t, 1.1);\n      var flick = 0.55 + 0.45 * Math.sin(time * 17 + p.seed * 3);\n      var a = fade * flick;\n      if (a <= 0.01) continue;\n      var r = p.r * (1 + 0.5 * t);\n      ctx.globalAlpha = a;\n      ctx.drawImage(EMBER_SPRITE, p.x - r * 2.2, p.y - r * 2.2, r * 4.4, r * 4.4);\n    }\n    ctx.globalAlpha = 1;\n  }\n```\n\nSmoke:\n```js\n  function drawSmoke() {\n    ctx.globalCompositeOperation = 'source-over';\n    for (var i = 0; i < smoke.length; i++) {\n      var p = smoke[i];\n      var t = p.life / p.maxLife;\n      var a = Math.min(1, t * 3) * Math.pow(1 - t, 1.4) * 0.10;\n      if (a <= 0.002) continue;\n      var r = p.r * (1 + 1.6 * t);\n      ctx.globalAlpha = a;\n      ctx.drawImage(SMOKE_SPRITE, p.x - r, p.y - r, r * 2, r * 2);\n    }\n    ctx.globalAlpha = 1;\n  }\n```\n\nLogs:\n```js\n  function drawLogs(time) {\n    for (var i = 0; i < logs.length; i++) {\n      var L = logs[i];\n      var cx = L.x * W, cy = L.y * H;\n      var w = L.w * W, h = L.h * H;\n      ctx.save();\n      ctx.translate(cx, cy);\n      ctx.rotate(L.a);\n      var g = ctx.createLinearGradient(0, -h * 0.5, 0, h * 0.5);\n      g.addColorStop(0, '#4a2c1a');\n      g.addColorStop(0.35, '#2a150c');\n      g.addColorStop(1, '#0e0604');\n      ctx.fillStyle = g;\n      roundRect(ctx, -w * 0.5, -h * 0.5, w, h, h * 0.5);\n      ctx.fill();\n      ctx.globalCompositeOperation = 'lighter';\n      for (var j = 0; j < L.spots.length; j++) {\n        var s = L.spots[j];\n        var pulse = 0.35 + 0.65 * (0.5 + 0.5 * Math.sin(time * s.sp + s.ph));\n        var"
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