:root{--bg: #0f1a30;--surface: #1b2a4a;--surface-2: #24355c;--text: #eef2fb;--muted: #a9b4cf;--accent: #5b8cff;--correct: #2faf6b;--wrong: #e0574f;--radius: 12px;--focus: #ffd34d;color-scheme:dark}*{box-sizing:border-box}html,body,#root{margin:0;min-height:100%}body{background:var(--bg);color:var(--text);font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;font-size:18px;line-height:1.5}:focus-visible{outline:3px solid var(--focus);outline-offset:2px}a{color:var(--accent)}button{font:inherit;cursor:pointer;border:0;border-radius:var(--radius);padding:.6rem 1rem;background:var(--accent);color:#fff;min-height:44px}button:disabled{opacity:.5;cursor:not-allowed}button.secondary{background:var(--surface-2);color:var(--text)}input,select{font:inherit;padding:.5rem .6rem;border-radius:8px;border:1px solid var(--surface-2);background:var(--surface);color:var(--text);min-height:44px}.app-shell{min-height:100vh;display:flex;flex-direction:column}.app-header{display:flex;align-items:center;justify-content:space-between;gap:1rem;padding:.75rem 1.25rem;background:var(--surface);flex-wrap:wrap}.app-header nav{display:flex;gap:.75rem;flex-wrap:wrap}.app-header nav a{padding:.4rem .6rem;border-radius:8px}.app-header nav a[aria-current=page]{background:var(--surface-2)}main{flex:1;width:100%;max-width:960px;margin:0 auto;padding:1.25rem}.card{background:var(--surface);border-radius:var(--radius);padding:1rem 1.25rem;margin-bottom:1rem}.grid{display:grid;gap:1rem;grid-template-columns:1fr}.filters{display:grid;gap:.75rem;grid-template-columns:1fr;margin-bottom:1rem}.scoreboard{display:flex;gap:1.5rem;flex-wrap:wrap;margin-bottom:1rem}.scoreboard .stat{background:var(--surface-2);padding:.5rem .9rem;border-radius:8px}.reveal{margin-top:1rem;padding:.75rem 1rem;border-radius:8px;background:var(--surface-2)}.reveal.correct{border-left:4px solid var(--correct)}.reveal.wrong{border-left:4px solid var(--wrong)}.flashcard{background:var(--surface-2);border-radius:var(--radius);padding:1.5rem;min-height:160px;width:100%;text-align:center;font-size:1.4rem}.choice-list{display:grid;gap:.6rem;margin:1rem 0}.choice-list button{background:var(--surface-2);color:var(--text);text-align:left}.choice-list button[aria-pressed=true]{background:var(--accent);color:#fff}.error-banner{background:var(--wrong);color:#fff;padding:.75rem 1rem;border-radius:8px;margin-bottom:1rem}.visually-hidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}@media(min-width:768px){.grid{grid-template-columns:repeat(2,1fr)}.filters{grid-template-columns:repeat(3,1fr);align-items:end}}@media(min-width:1024px){.grid{grid-template-columns:repeat(3,1fr)}}