@import url('https://fonts.googleapis.com/css2?family=Roboto+Condensed:wght@900&family=IBM+Plex+Mono:wght@400;500&display=swap');
:root{--paper:#faf8f3;--ink:#111;--muted:#75736e;--rule:#c9c5be;--mono:'IBM Plex Mono','Courier New',monospace}
*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:Arial,Helvetica,sans-serif}button,input{font:inherit}button{color:inherit;cursor:pointer}button:focus-visible,input:focus-visible{outline:2px solid var(--ink);outline-offset:5px}button:disabled{opacity:.45;cursor:wait}main{max-width:1120px;margin:auto;padding:62px 40px 26px}header{margin-bottom:46px}h1{font-family:'Roboto Condensed','Arial Narrow',Impact,sans-serif;font-weight:900;font-size:clamp(62px,7.8vw,112px);line-height:1;letter-spacing:-3.8px;margin:0 0 25px}.metadata{display:flex;flex-wrap:wrap;gap:10px 28px;font:10px/1.5 var(--mono);letter-spacing:1.1px}.metadata span:not(:first-child){color:var(--muted)}.experiment{max-width:960px}.stage{position:relative;border:1px solid #494844;aspect-ratio:1.6;user-select:none;-webkit-user-select:none;touch-action:pan-y;isolation:isolate}.stage svg{display:block;width:100%;height:100%;pointer-events:none}.stage-label,.stage-bottom{position:absolute;left:13px;right:13px;display:flex;justify-content:space-between;gap:12px;pointer-events:none;font:10px/1.5 var(--mono);letter-spacing:.8px;color:var(--muted)}.stage-label{top:13px}.stage-bottom{bottom:13px;font-size:9px}.stage-bottom #gesture{color:#55534f}.stage.grabbing{cursor:grabbing}.star-control{position:absolute;left:50%;top:50%;width:40%;height:62%;transform:translate(-50%,-50%);background:transparent;border:0;cursor:grab;touch-action:none;border-radius:50%;padding:0}.stage.grabbing .star-control{cursor:grabbing}.star-control:focus-visible{outline:1px dashed #888;outline-offset:12px}#handles circle{fill:var(--paper);stroke:var(--ink);stroke-width:1.2;r:4;opacity:0;transition:opacity .2s}.stage.engaged #handles circle{opacity:.65}.stage.grabbing #handles circle{opacity:0}.caption{display:flex;justify-content:space-between;gap:14px;font:10px/1.5 var(--mono);letter-spacing:.9px;margin-top:12px}.caption span:last-child{color:var(--muted)}.controls{display:flex;align-items:center;gap:14px;margin-top:30px;flex-wrap:wrap}.controls button{border:0;background:transparent;padding:12px 6px;min-height:44px;font:11px/1.5 var(--mono);white-space:nowrap}.controls .primary{display:flex;align-items:center;gap:14px;background:var(--ink);color:var(--paper);padding:13px 19px;min-width:176px;justify-content:center;border:1px solid var(--ink)}.primary:hover{background:#333}.play-icon{font-family:Arial,sans-serif;font-size:18px;line-height:12px}.control-end{display:flex;gap:17px;margin-left:auto}.control-end button{color:#66645f;font-size:10px}.control-end button[aria-pressed=true]{color:var(--ink);text-decoration:underline;text-underline-offset:4px}.player{padding:18px 0 15px;border-bottom:1px solid var(--rule);margin-top:8px}.player[hidden]{display:none}.track-line{display:flex;gap:20px;justify-content:space-between;font:10px/1.6 var(--mono);letter-spacing:.5px}.track{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.player-row{display:flex;gap:12px;align-items:center;margin-top:12px;font:9px/1.4 var(--mono);color:var(--muted)}input[type=range]{width:100px;accent-color:#111;cursor:pointer;min-height:24px}.local-note{margin-left:auto;letter-spacing:.3px}#feedback{font:11px/1.6 var(--mono);margin:10px 0 0;color:#56534e}#feedback:empty{display:none}.keyboard-help{font-size:11px;line-height:1.6;color:var(--muted);margin:15px 0 0;max-width:700px}.notes{display:grid;grid-template-columns:1.4fr 1fr;gap:72px;margin-top:55px}.notes h2{font:10px/1.6 var(--mono);letter-spacing:1px;color:var(--muted);border-bottom:1px solid #55534f;padding-bottom:10px;margin:0 0 14px}.notes p{font-size:15px;line-height:1.65;margin:0 0 14px;max-width:560px}.notes .lead{font-size:24px;line-height:1.3;letter-spacing:-.4px}footer{margin-top:45px;padding-top:15px;border-top:1px solid var(--rule);font:9px/1.5 var(--mono);letter-spacing:.7px;color:var(--muted);display:flex;justify-content:space-between;gap:20px}
@media(min-width:1500px){main{padding-top:76px}}@media(max-width:700px){main{padding:34px 22px 22px}h1{font-size:clamp(53px,12vw,82px);letter-spacing:-2px;margin-bottom:20px}header{margin-bottom:28px}.metadata{font-size:8px;gap:8px 16px}.metadata span:last-child{display:none}.stage-label{left:9px;right:9px;top:9px;font-size:8px;letter-spacing:.1px}.stage-bottom{left:9px;right:9px;bottom:9px;font-size:7px;letter-spacing:.2px}.caption{font-size:8px;letter-spacing:.2px}.caption span:last-child{display:none}.controls{gap:5px 14px;margin-top:22px}.controls button{font-size:10px}.controls .primary{min-width:160px;padding:12px 15px}.control-end{margin-left:0;width:100%;justify-content:space-between;gap:12px}.control-end button{padding-left:0;padding-right:0}.keyboard-help{font-size:10px}.notes{gap:26px;grid-template-columns:1fr;margin-top:34px}.notes .lead{font-size:22px}.notes p{font-size:14px}.local-note{display:none}.stage{aspect-ratio:1.35}.stage svg{position:absolute;inset:0}.star-control{width:46%;height:60%}footer{margin-top:30px;font-size:8px}input[type=range]{min-height:34px}}
.star-control{width:52%;height:80%}
@media(max-width:700px){.stage{aspect-ratio:1.6}.star-control{width:56%;height:84%}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}#handles circle{transition:none}}
.stage.waves-active{touch-action:none}
/* Surface selector and charge indicator follow the original fine-rule styling. */
.surface-tools{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;margin-top:24px;padding-bottom:10px;border-bottom:1px solid var(--rule)}
.materials{display:flex;align-items:center;gap:4px}.materials>span{font:9px/1.5 var(--mono);color:var(--muted);letter-spacing:1px;margin-right:12px}
.surface-tools button,.exit-immersive{font:10px/1.5 var(--mono);min-height:44px;border:1px solid transparent;background:transparent;padding:10px 13px}
.materials button[aria-pressed=true]{border-color:var(--ink);background:var(--ink);color:var(--paper)}
#immersive{color:var(--muted);padding-right:0}.surface-tools+.controls{margin-top:16px}
.charge-meter{position:absolute;bottom:43px;left:50%;transform:translateX(-50%);width:110px;height:2px;background:#c9c5be;opacity:0;transition:opacity .15s;pointer-events:none}.charge-meter span{display:block;width:100%;height:100%;background:var(--ink);transform:scaleX(var(--charge,0));transform-origin:left}.charging .charge-meter{opacity:1}
.exit-immersive[hidden]{display:none}.exit-immersive{position:absolute;z-index:6;right:20px;top:14px;background:var(--paper);border-color:var(--rule)}
.experiment.immersive{position:fixed;inset:0;z-index:1000;width:100%;height:100dvh;max-width:none;background:var(--paper);overflow:hidden}
.immersive .stage{position:absolute;inset:0;width:100%;height:100%;aspect-ratio:auto;border:0}
.immersive .stage svg{position:absolute;inset:0}.immersive .stage-label{left:22px;right:180px;top:26px}.immersive .stage-bottom{left:22px;right:22px;bottom:20px}
.immersive .caption,.immersive .keyboard-help,.immersive #feedback,.immersive #immersive{display:none}
.immersive .playground-dock{position:absolute;z-index:5;bottom:48px;left:50%;transform:translateX(-50%);width:min(960px,calc(100% - 44px));padding:8px 18px 10px;background:rgba(250,248,243,.94);backdrop-filter:blur(14px);border:1px solid var(--rule);transition:opacity .35s,transform .35s}
.immersive .surface-tools{margin:0;padding:0;border:0}.immersive .controls{margin:0}.immersive .player{padding:4px 0 0;margin:0;border:0}.immersive .track-line{display:none}.immersive .player-row{margin:0}.immersive .charge-meter{bottom:36px}
.immersive.is-quiet .playground-dock{opacity:0;pointer-events:none;transform:translate(-50%,12px)}
.immersive.is-quiet .playground-dock:has(:focus-visible){opacity:1;pointer-events:auto;transform:translateX(-50%)}
@media(max-width:700px){h1{font-size:clamp(42px,10.5vw,82px)}.surface-tools{gap:4px;margin-top:18px}.surface-tools button{padding:9px 10px}.materials>span{margin-right:5px}.immersive .playground-dock{bottom:42px;width:calc(100% - 24px);padding:6px 12px}.immersive .control-end{width:auto;margin-left:auto;gap:10px}.immersive .controls{gap:2px 10px}.immersive .stage-label{font-size:7px;right:150px}.exit-immersive{right:12px;font-size:9px}.immersive .player-row{justify-content:flex-end}.immersive .local-note{display:none}}
@media(prefers-reduced-motion:reduce){.charge-meter,.immersive .playground-dock{transition:none}}
.immersive .surface-tools{margin-bottom:8px}

/* Water optics live below the SVG; labels and controls stay crisp. */
#water-surface{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;z-index:0}
.stage.water-active{touch-action:none}
.stage svg{position:relative;z-index:1}.stage-label,.stage-bottom,.charge-meter{z-index:3}.star-control{z-index:2}
/* Five tracks, one simple row. */
.track-library{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:6px;margin-top:16px}
.track-library button{min-height:44px;padding:10px 6px;border:1px solid var(--rule);background:transparent;font:10px/1.4 var(--mono);letter-spacing:.7px;transition:background-color .16s,border-color .16s,transform .16s,box-shadow .16s}
.track-library [data-track=bounce]{--track-color:#bea3ed;--track-tint:#ece2fa;--track-edge:#7d54b4}
.track-library [data-track=skip]{--track-color:#9bdbc0;--track-tint:#dff3e9;--track-edge:#3c866c}
.track-library [data-track=snap]{--track-color:#ff9787;--track-tint:#ffe5de;--track-edge:#b65049}
.track-library [data-track=knock]{--track-color:#efc36d;--track-tint:#f9edcf;--track-edge:#98702b}
.track-library [data-track=rush]{--track-color:#9abcf3;--track-tint:#e0eafb;--track-edge:#4d70ac}
.track-library button:hover,.track-library button:focus-visible{background:var(--track-tint);border-color:var(--track-edge);box-shadow:0 2px 0 var(--track-edge);transform:translateY(-2px)}
.track-library button:focus-visible{outline-color:var(--track-edge)}
.track-library button[aria-pressed=true]{color:var(--ink);background:var(--track-color);border-color:var(--track-edge)}
.track-library button:active{background:var(--track-color);transform:translateY(1px) scale(.98);box-shadow:none}
@media(prefers-reduced-motion:reduce){.track-library button{transition:none}.track-library button:hover,.track-library button:focus-visible,.track-library button:active{transform:none}}
.track-library+.controls{margin-top:12px}
.immersive .track-library{margin:4px 0 8px;gap:5px}.immersive .track-library+.controls{margin-top:0}
@media(max-width:700px){.track-library{gap:4px}.track-library button{font-size:9px;letter-spacing:0;padding:9px 3px}}

.player-row{margin-top:0}.elapsed{font:10px/1.6 var(--mono);font-variant-numeric:tabular-nums;min-width:35px;color:var(--muted)}

/* Material samples: readable labels above their light/static layers. */
.materials button{position:relative;isolation:isolate;overflow:hidden;border-color:var(--rule);will-change:transform}
.materials button>span{position:relative;z-index:2}
.materials button::before,.materials button::after{content:'';position:absolute;inset:0;pointer-events:none;z-index:1;opacity:0}
.materials button::before{background:linear-gradient(115deg,transparent 10%,#fff9 46%,transparent 80%);opacity:calc(var(--material-hit,0)*.35)}
.materials button[aria-pressed=true]{box-shadow:inset 0 1px 0 #ffffff85,inset 0 -1px 2px #0002}
.materials [data-material=ink][aria-pressed=true]{background:linear-gradient(135deg,#353438,#111 65%,#28262c);border-color:#111;color:#faf8f3}
.materials [data-material=pearl]{color:var(--ink);background:transparent;border-color:var(--rule)}
.materials [data-material=pearl][aria-pressed=true]{color:#282330;border-color:#8f819e;background:linear-gradient(115deg,#b6adcd 0%,#ede1e2 22%,#fffdf5 43%,#c5dce5 62%,#f4e4cd 82%,#b9b1cc 100%)}
.materials [data-material=electric]{color:var(--ink);border-color:var(--rule);background:transparent}
.materials [data-material=electric][aria-pressed=true]{color:#1d1026;border-color:#84629c;background:linear-gradient(110deg,#d19aef,#ffacc9 24%,#ffdc83 46%,#98dfb4 65%,#8ac9f4 83%,#b798eb)}
.materials [data-material=pearl].material-flash::after{background:linear-gradient(110deg,transparent 20%,#fff 47%,#fff9 53%,transparent 80%);animation:pearl-button-shine .65s ease-out both}
.materials [data-material=electric].material-flash::after{background:repeating-linear-gradient(0deg,#fff9 0 1px,transparent 1px 4px),repeating-linear-gradient(93deg,#3e175e88 0 1px,transparent 1px 8px);animation:electric-button-static .42s steps(1,end) both}
.materials button:focus-visible{outline:2px solid #685475;outline-offset:4px}
.materials button:active>span{opacity:.75}
@keyframes pearl-button-shine{0%{transform:translateX(-110%);opacity:0}20%{opacity:.85}80%{opacity:.7}100%{transform:translateX(110%);opacity:0}}
@keyframes electric-button-static{0%{opacity:.55;transform:translate(0,0);clip-path:inset(12% 0 45%)}18%{opacity:.28;transform:translate(3px,-2px);clip-path:inset(55% 0 9%)}38%{opacity:.5;transform:translate(-3px,1px);clip-path:inset(4% 0 65%)}58%{opacity:.2;transform:translate(2px,2px);clip-path:inset(38% 0 25%)}78%{opacity:.38;transform:translate(-2px,-1px);clip-path:inset(70% 0 2%)}100%{opacity:0;transform:none}}
.experiment[data-motion=less] .materials button::after{animation:none;opacity:0}