:root{color-scheme:light}*{box-sizing:border-box}body{margin:0;font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,Helvetica,Arial,Apple Color Emoji,Segoe UI Emoji}a{color:inherit}.container{max-width:960px;margin:0 auto;padding:24px}.card{border:1px solid #e5e7eb;border-radius:16px;padding:16px}.row{display:flex;gap:12px;flex-wrap:wrap}input,textarea{width:100%;padding:10px 12px;border:1px solid #d1d5db;border-radius:12px;font-size:14px}button{padding:10px 14px;border-radius:12px;border:1px solid #d1d5db;background:#111827;color:#fff;cursor:pointer}button.secondary{background:#fff;color:#111827}small.muted{color:#6b7280}hr{border:0;border-top:1px solid #e5e7eb;margin:16px 0}.chat{display:flex;flex-direction:column;gap:10px}.bubble{padding:10px 12px;border-radius:14px;max-width:85%;white-space:pre-wrap}.bubble.student{align-self:flex-end;background:#111827;color:#fff}.bubble.assistant{align-self:flex-start;background:#f3f4f6}