@import "https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@400;500;600;700;800&family=Inter:wght@400;500;600;700&display=swap";
:root{--primary:#2563eb;--primary-hover:#1d4ed8;--primary-light:#eff6ff;--primary-border:#bfdbfe;--secondary:#7c3aed;--secondary-hover:#6d28d9;--secondary-light:#f5f3ff;--secondary-border:#ddd6fe;--bg-color:#f8fafc;--card-bg:#fff;--success:#16a34a;--success-light:#f0fdf4;--success-border:#bbf7d0;--warning:#f59e0b;--warning-light:#fffbeb;--warning-border:#fde68a;--danger:#dc2626;--danger-light:#fef2f2;--danger-border:#fecaca;--text-main:#0f172a;--text-muted:#64748b;--text-subtle:#94a3b8;--border-color:#e2e8f0;--border-color-subtle:#f1f5f9;--border-radius:12px;--border-radius-sm:8px;--border-radius-lg:16px;--border-radius-full:9999px;--shadow-xs:0 1px 2px 0 #0000000a;--shadow-sm:0 1px 3px 0 #0000000f, 0 1px 2px -1px #0000000a;--shadow-md:0 4px 6px -1px #00000012, 0 2px 4px -2px #0000000d;--shadow-lg:0 10px 15px -3px #00000014, 0 4px 6px -4px #0000000a}*{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth}body{background-color:var(--bg-color);color:var(--text-main);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;font-family:Be Vietnam Pro,Inter,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;line-height:1.6}h1,h2,h3,h4,h5,h6{color:var(--text-main);letter-spacing:-.02em;font-family:Be Vietnam Pro,sans-serif;font-weight:700;line-height:1.3}a{color:inherit;text-decoration:none}img{max-width:100%;height:auto}.container{max-width:1240px;margin:0 auto;padding:0 20px}.card{background:var(--card-bg);border:1px solid var(--border-color);border-radius:var(--border-radius);box-shadow:var(--shadow-sm);padding:1.5rem;transition:transform .2s,box-shadow .2s,border-color .2s}.card:hover{box-shadow:var(--shadow-md);border-color:#cbd5e1}.btn{border-radius:var(--border-radius-sm);cursor:pointer;white-space:nowrap;border:1px solid #0000;justify-content:center;align-items:center;gap:8px;min-height:44px;padding:0 1.25rem;font-family:Be Vietnam Pro,sans-serif;font-size:.95rem;font-weight:600;transition:all .2s;display:inline-flex}.btn-primary{background:var(--primary);color:#fff;border-color:var(--primary)}.btn-primary:hover{background:var(--primary-hover);border-color:var(--primary-hover);transform:translateY(-1px);box-shadow:0 4px 12px #2563eb40}.btn-secondary{background:var(--secondary);color:#fff;border-color:var(--secondary)}.btn-secondary:hover{background:var(--secondary-hover);transform:translateY(-1px);box-shadow:0 4px 12px #7c3aed40}.btn-outline{color:var(--primary);border:1.5px solid var(--primary-border);background:#fff}.btn-outline:hover{background:var(--primary-light);border-color:var(--primary)}.badge{border-radius:var(--border-radius-full);align-items:center;gap:4px;padding:.25rem .65rem;font-size:.8rem;font-weight:600;line-height:1;display:inline-flex}.badge-primary{background:var(--primary-light);color:var(--primary);border:1px solid var(--primary-border)}.badge-secondary{background:var(--secondary-light);color:var(--secondary);border:1px solid var(--secondary-border)}.badge-success{background:var(--success-light);color:var(--success);border:1px solid var(--success-border)}.badge-warning{background:var(--warning-light);color:var(--warning);border:1px solid var(--warning-border)}.badge-danger{background:var(--danger-light);color:var(--danger);border:1px solid var(--danger-border)}.quiz-math-img{object-fit:contain;border-radius:var(--border-radius-sm);border:1px solid var(--border-color);background:#fff;width:auto;max-width:100%;height:auto;margin:12px auto;display:block}.katex{overflow-wrap:break-word;word-break:break-word;font-size:1.06em}.katex-display{-webkit-overflow-scrolling:touch;margin:1em 0;padding:.4rem 0;overflow:auto hidden}.katex-display>.katex{text-align:left;max-width:100%;margin:0;display:inline-block}.katex-display::-webkit-scrollbar{height:5px}.katex-display::-webkit-scrollbar-track{background:0 0}.katex-display::-webkit-scrollbar-thumb{background:var(--border-color);border-radius:3px}.katex-display::-webkit-scrollbar-thumb:hover{background:var(--text-muted)}