:root{font-family:ui-sans-serif,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;color:#172b4d;background:#f3f6fb;font-size:16px;--blue:#245ad6;--muted:#586a80;--line:#d6e0ee}*{box-sizing:border-box}body{margin:0}button,a{touch-action:manipulation}button{font:inherit;cursor:pointer;border:1px solid #bacadd;border-radius:9px;padding:12px 15px;background:white;color:#172b4d;font-weight:600}button:disabled{opacity:.45;cursor:default}button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid #e88b22;outline-offset:4px}a{color:var(--blue)}header{max-width:1240px;margin:auto;padding:22px 28px;display:flex;align-items:center;justify-content:space-between;gap:20px;border-bottom:1px solid var(--line)}header a{text-decoration:none;font-weight:750}header>span{font-size:11px;letter-spacing:1.4px;color:var(--muted)}header p{margin:0;font-size:14px;font-weight:650}main{max-width:1240px;padding:0 28px;margin:auto}.intro{padding:30px 0 22px}.eyebrow{font-size:11px;font-weight:750;letter-spacing:1.5px;color:var(--blue);margin:0 0 8px}h1{font-size:clamp(30px,4vw,46px);letter-spacing:-1.4px;margin:0 0 12px;line-height:1.1}.intro>p:last-child{margin:0;line-height:1.6;color:var(--muted);max-width:660px}#missions{display:flex;gap:8px;margin:0 0 24px;flex-wrap:wrap}#missions button{min-width:75px;padding:11px 16px;background:transparent;position:relative}#missions button[aria-current=true]{background:var(--blue);color:white;border-color:var(--blue)}#missions button.done:after{content:'✓';margin-left:7px;color:#178563}#missions button.done[aria-current=true]:after{color:white}.workshop{display:grid;grid-template-columns:minmax(0,1.55fr) minmax(310px,1fr);gap:24px}.bench{background:#132741;border-radius:18px;color:#eaf1fb;padding:28px;overflow:hidden;align-self:start}.bench-top{display:flex;justify-content:space-between;align-items:center;gap:20px}.bench .eyebrow{color:#88c5ff}h2{font-size:25px;margin:0;letter-spacing:-.5px}.bench-top>span{font:35px Georgia,serif;color:#81e3d9}.bench>p{line-height:1.5;color:#c3d1e4;font-size:15px}#board{position:relative;width:100%;aspect-ratio:600/380;margin:18px 0 8px}#bonds{width:100%;height:100%;position:absolute;inset:0;overflow:visible}#atoms{position:absolute;inset:0}.atom{position:absolute;transform:translate(-50%,-50%);width:68px;height:68px;padding:0;border-radius:50%;border:3px solid transparent;color:#12233b;box-shadow:0 4px 15px #0002;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:3px;font-size:23px;z-index:2;transition:box-shadow .12s}.atom.H{background:#e9f1ff}.atom.O{background:#eb9690}.atom.N{background:#91b4ff}.atom.C{background:#84d5cc}.atom[aria-pressed=true]{border-color:white;box-shadow:0 0 0 5px #ffc46b}.atom.full:after{content:'✓';position:absolute;right:-4px;top:-7px;background:#1c795c;color:white;border:2px solid #132741;border-radius:50%;font-size:13px;width:20px;height:20px;display:grid;place-items:center}.atom small{font-size:11px;font-weight:650;letter-spacing:2px}.legend{display:flex;gap:10px 24px;flex-wrap:wrap;font-size:12px;color:#deebfb;line-height:1.6}.legend i{display:inline-block;vertical-align:middle;width:20px;height:3px;background:#f4c375;margin-right:8px}.bench .model-note{font-size:12px;margin-bottom:0;line-height:1.55;color:#aabfd9}.controls{border:1px solid var(--line);background:white;border-radius:18px;padding:26px}.controls>p:not(.eyebrow){color:var(--muted);line-height:1.5;font-size:15px}.actions{display:grid;gap:10px}.primary{background:var(--blue);color:white;border-color:var(--blue)}.primary:hover:enabled{background:#1949b7}.tools{display:flex;flex-wrap:wrap;gap:6px;margin:12px 0}.tools button{font-size:13px;padding:9px 10px;border-color:transparent;background:#f0f4fa}#feedback{min-height:46px;border-left:3px solid #8caddb;padding-left:12px}#success{padding:20px;background:#eaf7f1;border:1px solid #b8ddca;border-radius:12px;margin:16px 0}.stamp{font-size:11px;letter-spacing:1px;font-weight:750;color:#237455}h3{font-size:18px;margin:12px 0}#success p{font-size:15px;line-height:1.5}#success button{width:100%;font-size:14px}.progress-box{border-top:1px solid var(--line);margin-top:22px;padding-top:4px}ul{padding:0;list-style:none}#atom-progress li{display:flex;justify-content:space-between;gap:20px;padding:9px 0;border-bottom:1px solid #edf1f7;font-size:14px}#atom-progress strong{color:var(--blue)}.small{font-size:12px;color:var(--muted);line-height:1.6}details{margin:26px 0;background:white;border:1px solid var(--line);border-radius:10px;padding:20px 24px}summary{font-weight:650;cursor:pointer}details p{font-size:16px;line-height:1.65;max-width:850px}footer{font-size:13px;line-height:1.6;color:var(--muted);padding:0 0 28px}[hidden]{display:none!important}@media(max-width:850px){.workshop{grid-template-columns:1fr}.bench{padding:24px}#board{max-width:600px;margin-left:auto;margin-right:auto}.controls{display:block}.actions{grid-template-columns:1fr 1fr}header>span{display:none}}@media(max-width:480px){header{padding:18px;gap:10px;font-size:14px}header p{font-size:12px}main{padding:0 18px}.intro{padding-top:24px}h1{letter-spacing:-.8px}.bench{padding:20px 16px}.atom{width:52px;height:52px;font-size:20px}.atom small{font-size:9px;letter-spacing:1px}#missions{gap:7px}#missions button{min-width:64px;padding:10px 12px}.controls{padding:22px}h2{font-size:23px}.actions{grid-template-columns:1fr}.legend{font-size:11px;gap:6px}#board{margin-top:25px;margin-bottom:24px}.bench-top>span{font-size:29px}}@media(prefers-reduced-motion:reduce){.atom{transition:none}}

.atom:disabled{opacity:1}