:root{
  --oil:#F7C948;
  --oil-ring:#F58A4B;
  --water:#08C4D4;
  --glass:#ffffff;
  --ink:#111111;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Noto Sans, Arial, "Apple Color Emoji","Segoe UI Emoji";
  color:var(--ink);
  background:#fafafa;
}
.wrap{max-width:960px;margin:0 auto;padding:24px}
header h1{margin:0 0 8px;font-size:clamp(22px,3vw,32px)}
.desc{margin:0 0 16px;color:#333}
.stage{position:relative;border-radius:12px;background:white;border:1px solid #e7e7e7;padding:12px}
#scene{width:100%;height:min(72vh,640px);display:block;background:transparent}
.controls{display:flex;gap:8px;justify-content:center;margin-top:12px}
button{cursor:pointer;border:none;border-radius:999px;padding:10px 16px;font-weight:600}
button.primary{background:#111;color:#fff}
button.ghost{background:transparent;border:1px solid #bbb;color:#333}
button:disabled{opacity:.5;cursor:not-allowed}
.legend{display:flex;gap:8px;align-items:center;justify-content:center;margin-top:10px;color:#666;font-size:14px}
.chip{display:inline-flex;align-items:center;gap:6px;border-radius:999px;padding:6px 10px;border:1px dashed #ccc}
.chip::before{content:"";display:inline-block;width:12px;height:12px;border-radius:50%}
.chip.oil::before{background:var(--oil)}
.chip.water::before{background:var(--water)}
.chip.emulsifier::before{background:var(--oil-ring)}

@media (max-width:540px){
  .wrap{padding:14px}
}