@import"https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&display=swap";:root{--bg: #0b1020;--panel: #121830;--panel-2: #182042;--line: #262e52;--gold: #fbbf24;--sky: #38bdf8;--rose: #f43f5e;--txt: #e6e9f5;--dim: #8892b8}*{box-sizing:border-box}body{margin:0;background:radial-gradient(900px 500px at 85% -10%,rgba(251,191,36,.08),transparent 60%),radial-gradient(700px 500px at 8% 110%,rgba(56,189,248,.08),transparent 60%),var(--bg);color:var(--txt);font-family:Space Grotesk,system-ui,sans-serif;-webkit-font-smoothing:antialiased}.app{max-width:1080px;margin:0 auto;padding:20px 16px 44px}header{display:flex;align-items:center;gap:16px;border-bottom:1px solid var(--line);padding-bottom:14px;flex-wrap:wrap}.mark{width:52px;height:52px;border-radius:13px;display:grid;place-items:center;font-size:26px;background:linear-gradient(145deg,#2a2308,#0e1120);border:1px solid var(--gold);color:var(--gold);box-shadow:0 0 20px #fbbf244d}h1{margin:0;font-size:22px;letter-spacing:2.5px;color:#fff;font-weight:700}header p{margin:3px 0 0;color:var(--dim);font-size:12.5px}.badges{margin-left:auto}.cta{color:#1c1503;background:var(--gold);font-weight:700;font-size:12.5px;text-decoration:none;padding:9px 16px;border-radius:20px;white-space:nowrap;display:inline-block}.cta:hover{filter:brightness(1.08)}.layout{display:grid;grid-template-columns:260px 1fr;gap:16px;margin-top:16px}.topic-list{display:flex;flex-direction:column;gap:6px}.topic-btn{text-align:left;font-family:inherit;cursor:pointer;background:var(--panel);color:var(--dim);border:1px solid var(--line);border-radius:10px;padding:10px 12px;display:flex;flex-direction:column;gap:2px}.topic-btn:hover{border-color:var(--gold)}.topic-btn.on{border-color:var(--gold);background:var(--panel-2);color:var(--txt)}.topic-name{font-size:13px;font-weight:600}.topic-blurb{font-size:11px;color:var(--dim);line-height:1.3}.panel{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:18px;min-height:400px}.seg{display:flex;gap:6px;background:var(--panel-2);border:1px solid var(--line);border-radius:9px;padding:4px;width:fit-content}.seg button{font-family:inherit;font-size:12.5px;cursor:pointer;background:transparent;color:var(--dim);border:none;padding:8px 16px;border-radius:6px}.seg button:hover{color:#fff}.seg button.on{background:var(--gold);color:#1c1503;font-weight:600}.cards{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin-top:16px}.ref-card{background:#0b0f22;border:1px solid var(--line);border-radius:10px;padding:12px 14px;display:flex;flex-direction:column;gap:4px}.ref-title{font-size:12.5px;font-weight:600;color:var(--sky)}.ref-formula{font-size:13.5px;font-family:ui-monospace,monospace;color:var(--txt)}.ref-note{font-size:11.5px;color:var(--dim)}.practice{margin-top:16px}.stats-row{display:flex;gap:10px;margin-bottom:16px}.stat{flex:1;background:var(--panel-2);border:1px solid var(--line);border-radius:10px;padding:10px 14px;display:flex;flex-direction:column;gap:4px}.stat-label{font-size:10.5px;color:var(--dim);text-transform:uppercase;letter-spacing:.5px}.stat-val{font-size:20px;font-weight:700;font-family:ui-monospace,monospace;color:var(--gold)}.di-chart{display:flex;align-items:flex-end;gap:16px;height:130px;margin-bottom:16px;background:#0b0f22;border:1px solid var(--line);border-radius:10px;padding:12px 16px 8px}.di-bar-wrap{display:flex;flex-direction:column;align-items:center;justify-content:flex-end;gap:4px;flex:1;height:100%}.di-bar{width:32px;background:linear-gradient(180deg,var(--sky),#1d6fa5);border-radius:4px 4px 0 0}.di-bar-label{font-size:10px;color:var(--dim);text-align:center}.di-bar-val{font-size:11px;color:var(--txt);font-family:ui-monospace,monospace}.question{font-size:14.5px;color:var(--txt);margin:0 0 12px}.answer-form{display:flex;align-items:center;gap:8px;flex-wrap:wrap}.answer-form input{font-family:inherit;font-size:13px;background:var(--panel-2);color:var(--txt);border:1px solid var(--line);border-radius:7px;padding:9px 12px;width:140px}.answer-form input:focus{border-color:var(--gold);outline:none}.submit-btn{font-family:inherit;font-size:12.5px;font-weight:600;cursor:pointer;background:var(--gold);color:#1c1503;border:none;padding:9px 16px;border-radius:7px}.ghost{font-family:inherit;font-size:12px;cursor:pointer;background:var(--panel-2);color:var(--dim);border:1px solid var(--line);padding:9px 13px;border-radius:7px}.ghost:hover{color:#fff;border-color:var(--gold)}.feedback{margin-top:12px;font-size:13.5px;font-weight:600}.feedback.correct{color:#22c55e}.feedback.wrong{color:var(--rose)}.pdf-strip{margin-top:20px;background:linear-gradient(90deg,rgba(251,191,36,.08),transparent);border:1px solid rgba(251,191,36,.25);border-radius:12px;padding:16px 20px;display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap}.pdf-title{display:block;font-size:14px;font-weight:700;color:#fff}.pdf-sub{display:block;font-size:12px;color:var(--dim);margin-top:3px;max-width:480px}footer{text-align:center;color:var(--dim);font-size:11.5px;margin-top:18px;border-top:1px solid var(--line);padding-top:12px}@media (max-width: 780px){.layout,.cards{grid-template-columns:1fr}}