:root{font-family:Inter,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;color:#172033;background:#eef3f8}*{box-sizing:border-box}body{margin:0}main{width:min(980px,calc(100% - 32px));margin:0 auto;padding:32px 0 80px}header{margin-bottom:24px}header h1{margin-bottom:6px}header p{margin-top:0;color:#5f6b7a}.panel{background:#fff;border-radius:16px;padding:24px;margin-bottom:20px;box-shadow:0 8px 24px #14253f14}label{display:block;margin-bottom:16px;font-weight:600}input,select{display:block;width:100%;margin-top:7px;padding:12px;border:1px solid #cdd6e1;border-radius:10px;font:inherit}button{border:0;border-radius:10px;background:#2864dc;color:#fff;padding:11px 18px;font:inherit;font-weight:700;cursor:pointer}button:disabled{opacity:.55;cursor:not-allowed}button.secondary{background:#e7eef9;color:#234e9b}.actions{display:flex;gap:10px;margin-top:12px}.question-card,.example,.mastery,.mistake{border:1px solid #dce3ec;border-radius:12px;padding:16px;margin:14px 0}.hint{margin-top:10px;padding:10px;border-radius:8px;background:#fff6d8}.feedback{margin-top:10px;padding:10px;border-radius:8px;background:#eaf6ed}.error{margin-bottom:18px;padding:12px;border-radius:10px;background:#ffe8e8;color:#8c1d1d}.progress-heading{display:flex;align-items:center;justify-content:space-between;gap:16px}@media(max-width:640px){main{width:min(100% - 20px,980px);padding-top:18px}.panel{padding:18px;border-radius:12px}.progress-heading{align-items:flex-start;flex-direction:column}}