:root{--bg: #0e1116;--panel: #181d25;--line: #2a323d;--ink: #eef3f7;--dim: #93a4b3;--accent: #4a90c0;--good: #3fb37f;--bad: #d05a64;--syn: #4a90c0;--ant: #c08a4a}*{box-sizing:border-box}html,body{margin:0;height:100%}body{background:radial-gradient(900px 560px at 50% -8%,#16202a,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:#06141b}.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)}.scoreboard{display:flex;gap:8px;justify-content:center;margin:6px 0 10px}.readout{background:var(--panel);border:1px solid var(--line);border-radius:10px;padding:6px 12px;min-width:78px;text-align:center;font-weight:800;font-size:18px}.readout span{display:block;color:var(--dim);font-size:10px;letter-spacing:1.5px;font-weight:700}.stage{position:relative}.relation-banner{text-align:center;padding:10px;border-radius:12px;margin-bottom:10px;border:1px solid var(--line);font-weight:800;letter-spacing:1px;font-size:15px}.relation-banner.synonym{background:#4a90c029;border-color:var(--syn);color:#9cc8e6}.relation-banner.antonym{background:#c08a4a29;border-color:var(--ant);color:#e6c89c}.relation-banner .tag{font-size:11px;letter-spacing:2px;opacity:.8;display:block;margin-bottom:2px}.prompt{text-align:center;background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:20px 10px;margin-bottom:8px;font-size:34px;font-weight:800;letter-spacing:1px}.meter-track{height:10px;background:var(--panel);border:1px solid var(--line);border-radius:999px;overflow:hidden;margin-bottom:14px}.meter-fill{height:100%;width:100%;background:linear-gradient(90deg,var(--good),var(--accent));transition:width 80ms linear}.meter-fill.low{background:var(--bad)}.options{display:grid;gap:10px}.opt{background:var(--panel);border:1px solid var(--line);color:var(--ink);padding:16px;border-radius:12px;font:700 18px system-ui;cursor:pointer;text-align:center}.opt:hover:not(:disabled){border-color:var(--accent)}.opt.correct{background:#3fb37f40;border-color:var(--good)}.opt.wrong{background:#d05a6440;border-color:var(--bad)}.opt:disabled{cursor:default}.overlay{position:absolute;inset:0;background:#080b0ff0;border-radius:14px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px;text-align:center;padding:20px}.overlay.hidden{display:none}.overlay h2{margin:0;font-size:26px;color:var(--accent)}.overlay .stat{color:var(--dim);font-size:14px}.overlay .big{font-size:40px;font-weight:800;color:var(--ink)}.footer{text-align:center;color:var(--dim);font-size:12px;margin-top:14px;line-height:1.5}