:root{--paper:#fff;--paper-card:#fff;--ink:#16171a;--ink-soft:#6b6f76;--accent:#7b4fdb;--correct:#3f7a5c;--correct-bg:#e4f2ea;--incorrect:#b5533c;--incorrect-bg:#fbe9e4;--border:#ececec;--font-display:"Manrope",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;--font-body:"Manrope",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;--font-mono:ui-monospace,SFMono-Regular,Menlo,monospace;--radius:8px;--shadow:none}*{box-sizing:border-box}body,html{margin:0;padding:0;background:var(--paper);color:var(--ink);font-family:var(--font-body);-webkit-font-smoothing:antialiased}a{color:inherit}button{font-family:inherit}.shell{max-width:880px;margin:0 auto;padding:24px 20px 64px;min-height:100dvh}.brand{display:flex;align-items:center;justify-content:space-between;margin-bottom:28px}.brand-name{font-family:var(--font-display);font-size:18px;font-weight:500;letter-spacing:-.01em}.brand-tag{font-family:var(--font-mono);font-size:11px;color:var(--ink-soft);text-transform:uppercase;letter-spacing:.08em}.page-title{font-family:var(--font-display);font-size:22px;font-weight:500;line-height:1.2;margin:0 0 6px}.page-subtitle{color:var(--ink-soft);font-size:14px;margin:0 0 28px}.topic-grid{display:grid;grid-gap:8px;gap:8px}@media (min-width:700px){.topic-grid{grid-template-columns:repeat(2,1fr);gap:12px}}.topic-card{position:relative;display:flex;align-items:center;justify-content:space-between;gap:16px;background:var(--paper-card);border:1px solid var(--border);border-radius:var(--radius);padding:14px 16px;text-decoration:none;color:var(--ink);transition:border-color .15s ease}.topic-card:hover{border-color:var(--accent)}.topic-card:hover .topic-card-arrow,.topic-card:hover .topic-card-title{color:var(--accent)}.topic-card:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.topic-card-title{font-family:var(--font-display);font-size:14px;font-weight:500;margin:0 0 2px}.topic-card-meta{font-family:var(--font-mono);font-size:12px;color:var(--ink-soft)}.topic-card-arrow{font-size:16px;color:var(--ink-soft);flex-shrink:0}.pending-note{margin-top:28px;font-size:13px;color:var(--ink-soft);border-top:1px solid var(--border);padding-top:16px}.progress-row{display:flex;align-items:center;gap:10px;margin-bottom:24px}.progress-dots{display:flex;gap:5px;flex:1 1}.progress-dot{height:4px;border-radius:2px;flex:1 1;background:var(--border)}.progress-dot.filled{background:var(--ink)}.progress-dot.current{background:var(--accent)}.progress-count{font-family:var(--font-mono);font-size:12px;color:var(--ink-soft);white-space:nowrap}.card-stack{position:relative;margin-bottom:24px}.question-card{position:relative;background:var(--paper-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px 18px}.question-meta{font-family:var(--font-mono);font-size:11px;color:var(--ink-soft);text-transform:uppercase;letter-spacing:.06em;margin-bottom:10px}.question-text{font-family:var(--font-display);font-size:16px;font-weight:400;line-height:1.5;white-space:pre-line;margin:0 0 18px}.options{display:grid;grid-gap:8px;gap:8px}.option-button{display:flex;gap:12px;align-items:flex-start;text-align:left;width:100%;padding:12px 14px;border:1px solid var(--border);border-radius:var(--radius);background:var(--paper);cursor:pointer;font-size:14px;color:var(--ink)}.option-button:hover:not(:disabled){border-color:var(--ink-soft)}.option-button:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.option-button:disabled{cursor:default}.option-letter{font-family:var(--font-mono);font-weight:500;color:var(--ink-soft);flex-shrink:0}.option-button.correct{background:var(--correct-bg);border-color:var(--correct)}.option-button.correct .option-letter{color:var(--correct)}.option-button.incorrect{background:var(--incorrect-bg);border-color:var(--incorrect)}.option-button.incorrect .option-letter{color:var(--incorrect)}.feedback-row{margin-top:16px;display:flex;align-items:center;justify-content:space-between;gap:12px}.feedback-text{font-size:13px;font-weight:500}.feedback-text.correct{color:var(--correct)}.feedback-text.incorrect{color:var(--incorrect)}.next-button,.primary-button{background:var(--accent);color:#fff;border:none;border-radius:var(--radius);padding:10px 18px;font-size:13px;font-weight:500;cursor:pointer}.next-button:hover,.primary-button:hover{background:#6a3fc4}.next-button:focus-visible,.primary-button:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.summary-card{background:var(--paper-card);border:1px solid var(--border);border-radius:var(--radius);padding:28px 22px;text-align:center}.summary-score{font-family:var(--font-display);font-size:36px;font-weight:500;margin:0 0 6px}.summary-label{color:var(--ink-soft);font-size:13px;margin:0 0 24px}.summary-actions{display:flex;gap:10px;justify-content:center;flex-wrap:wrap}.secondary-link{display:inline-flex;align-items:center;padding:10px 18px;border-radius:var(--radius);border:1px solid var(--border);font-weight:500;color:var(--ink)}.back-link,.secondary-link{font-size:13px;text-decoration:none}.back-link{display:inline-block;margin-bottom:16px;color:var(--ink-soft)}.back-link:hover{color:var(--accent)}@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}.brand-left{display:flex;align-items:center;gap:10px}.brand-logo{display:block;border-radius:6px}.random-mix-card{display:flex;align-items:center;justify-content:space-between;gap:16px;background:var(--paper-card);color:var(--ink);border:1px solid var(--border);border-radius:var(--radius);padding:14px 16px;text-decoration:none;margin-bottom:20px;transition:border-color .15s ease}.random-mix-card:hover{border-color:var(--accent)}.random-mix-card:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.random-mix-card .topic-card-arrow{color:var(--accent)}.random-mix-title{font-family:var(--font-display);font-size:14px;font-weight:500;margin:0 0 2px;color:var(--ink)}.random-mix-meta{font-family:var(--font-mono);font-size:12px;color:var(--ink-soft)}.site-nav{justify-content:space-between;gap:12px;max-width:880px;margin:0 auto;padding:16px 20px;border-bottom:1px solid var(--border);background:var(--paper-card)}.site-nav,.site-nav-left{display:flex;align-items:center;flex-wrap:wrap}.site-nav-left{gap:24px}.site-nav-links{display:flex;align-items:center;gap:18px;flex-wrap:wrap}.site-nav-link{font-size:13px;font-weight:500;color:var(--ink-soft);text-decoration:none;padding:6px 14px;border-radius:999px;border:1px solid var(--border)}.site-nav-link.active,.site-nav-link:hover{color:var(--accent);border-color:var(--accent)}.site-nav{flex-direction:column;align-items:stretch}.site-nav-row{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px}.subject-badge{font-size:11px;font-weight:500;color:var(--accent);background:#f3eefc;padding:3px 9px;border-radius:999px;margin-left:4px}.long-questions-section{margin-top:32px}.section-title{font-family:var(--font-display);font-size:16px;font-weight:500;margin:0 0 12px}