:root{--bg: #0e1116;--panel: #181d25;--line: #2a323d;--ink: #eef3f7;--dim: #93a4b3;--accent: #b05f8a;--good: #4ec9b0;--a: #4ec9b0;--u: #6aa6ff;--g: #f0b03a;--c: #e06a8a}*{box-sizing:border-box}html,body{margin:0;height:100%}body{background:radial-gradient(900px 560px at 50% -8%,#1c1620,var(--bg));color:var(--ink);font-family:system-ui,-apple-system,Segoe UI,sans-serif;display:flex;justify-content:center;-webkit-user-select:none;user-select:none}#app{width:100%;max-width:520px;padding:12px 12px 26px}header{text-align:center;margin-bottom:6px}h1{margin:0;font-size:28px;letter-spacing:6px;font-weight:800;color:var(--accent)}.sub{margin:3px 0 0;color:var(--dim);font-size:13px}.bar{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;align-items:center;margin:10px 0}.seg{display:inline-flex;background:var(--panel);border:1px solid var(--line);border-radius:999px;overflow:hidden}.seg button{background:none;border:none;color:var(--dim);padding:6px 13px;font:600 13px system-ui;cursor:pointer}.seg button.active{background:var(--accent);color:#1a0a14}.btn{background:var(--panel);border:1px solid var(--line);color:var(--ink);padding:7px 14px;border-radius:999px;font:700 13px system-ui;cursor:pointer}.btn:hover{border-color:var(--accent)}.btn.primary{background:var(--accent);color:#1a0a14;border-color:var(--accent)}.scoreboard{display:flex;gap:10px;justify-content:center;margin:8px 0}.readout{background:#0a0e13;border:1px solid var(--line);border-radius:8px;padding:5px 14px;font:800 18px ui-monospace,monospace;color:var(--accent);min-width:84px;text-align:center}.readout span{color:var(--dim);font-size:11px;display:block;font-weight:600;letter-spacing:.5px}.diagrams{display:flex;flex-direction:column;gap:8px;margin:10px 0}.diagram{background:#0a0e13;border:1px solid var(--line);border-radius:8px;padding:6px 8px}.dlabel{color:var(--dim);font-size:11px;font-weight:700;letter-spacing:.5px;margin-bottom:2px}.dlabel .ok{color:var(--good)}.dlabel .no{color:var(--accent)}canvas{width:100%;height:auto;display:block}canvas.shake{animation:shake .4s}@keyframes shake{0%,to{transform:translate(0)}25%{transform:translate(-6px)}75%{transform:translate(6px)}}.stage{position:relative;display:flex;justify-content:center;margin-top:6px}.strand{display:flex;flex-wrap:wrap;gap:6px;justify-content:center;width:100%;padding:6px 0}.base{width:38px;height:38px;display:flex;align-items:center;justify-content:center;border-radius:8px;font-weight:800;font-size:18px;cursor:pointer;background:var(--panel);border:1px solid var(--line);color:var(--ink);position:relative}.base:hover{border-color:var(--accent)}.base.sel{box-shadow:0 0 0 2px var(--accent)}.base.ba{background:#11302b;color:var(--a)}.base.bu{background:#11233f;color:var(--u)}.base.bg{background:#332710;color:var(--g)}.base.bc{background:#3a141f;color:var(--c)}.base.paired:after{content:"";position:absolute;bottom:-3px;left:50%;transform:translate(-50%);width:6px;height:6px;border-radius:50%;background:var(--good)}.base.fragile{outline:2px dashed #f0b03a;outline-offset:1px}.overlay{position:absolute;inset:-8px;display:flex;align-items:center;justify-content:center;background:#080c10d1;border-radius:8px;backdrop-filter:blur(3px)}.overlay.hidden{display:none}.card{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:22px 26px;text-align:center;max-width:340px}.card h2{margin:0 0 6px;font-size:22px;color:var(--good)}.card p{margin:6px 0;color:var(--dim);font-size:14px}.card .row{display:flex;gap:8px;justify-content:center;margin-top:14px}.pad{display:grid;grid-template-columns:repeat(4,1fr);gap:6px;max-width:360px;margin:14px auto 0}.pad button{background:var(--panel);border:1px solid var(--line);color:var(--ink);padding:12px 0;border-radius:8px;font:800 18px ui-monospace,monospace;cursor:pointer}.pad button:hover{border-color:var(--accent)}.pad button[data-b=A]{color:var(--a)}.pad button[data-b=U]{color:var(--u)}.pad button[data-b=G]{color:var(--g)}.pad button[data-b=C]{color:var(--c)}.pad button.hint-btn{grid-column:span 4;font:700 14px system-ui;color:var(--accent)}.pad button.hint-btn:disabled{color:var(--dim);cursor:not-allowed;opacity:.55}.hint{text-align:center;color:var(--dim);font-size:12px;margin-top:12px;line-height:1.5}