:root{--bg:#f6f8fa;--bg-grad:linear-gradient(180deg, #f0f7f4 0%, #f6f8fa 320px);--surface:#fff;--primary:#1e7a5f;--primary-dark:#145c46;--primary-light:#e3f3ec;--accent:#3d7fb0;--accent-light:#e8f2f8;--warm:#d98c3d;--warm-light:#fbf0e0;--text:#1c2b27;--text-muted:#647671;--border:#e6ebe8;--success:#2f8f63;--success-bg:#e5f5ec;--caution:#c07f2a;--caution-bg:#faf0dd;--radius:18px;--radius-sm:12px;--shadow-sm:0 1px 3px #1428210f;--shadow:0 4px 20px #14282114;--shadow-lg:0 12px 32px #1428211f}*{box-sizing:border-box}html{scroll-behavior:smooth}body{background:var(--bg-grad), var(--bg);color:var(--text);-webkit-font-smoothing:antialiased;background-attachment:fixed;margin:0;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,system-ui,sans-serif}#root{min-height:100vh}.container{max-width:1100px;margin:0 auto;padding:0 20px}.btn{cursor:pointer;border:none;border-radius:999px;justify-content:center;align-items:center;gap:8px;padding:12px 26px;font-family:inherit;font-size:15px;font-weight:600;transition:transform .15s,box-shadow .15s,background .15s;display:inline-flex}.btn:active{transform:scale(.96)}.btn-primary{background:linear-gradient(135deg, var(--primary), var(--primary-dark));color:#fff;box-shadow:0 4px 14px #1e7a5f47}.btn-primary:hover{transform:translateY(-1px);box-shadow:0 6px 18px #1e7a5f5c}.btn-secondary{background:var(--surface);color:var(--primary);border:1.5px solid var(--border)}.btn-secondary:hover{background:var(--primary-light);border-color:var(--primary)}.btn-ghost{color:var(--text-muted);background:0 0}.btn-ghost:hover{color:var(--text);background:#0000000a}.btn:disabled{opacity:.5;cursor:not-allowed;box-shadow:none!important;transform:none!important}.btn-block{width:100%}.card{background:var(--surface);border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid #1428210a;padding:24px}.input{border-radius:var(--radius-sm);border:1.5px solid var(--border);background:var(--surface);width:100%;color:var(--text);padding:13px 16px;font-family:inherit;font-size:15px;transition:border-color .15s,box-shadow .15s}.input:focus{border-color:var(--primary);outline:none;box-shadow:0 0 0 3px #1e7a5f1f}.badge{letter-spacing:.02em;text-transform:uppercase;border-radius:999px;padding:4px 12px;font-size:12px;font-weight:700;display:inline-block}.badge-normal{background:var(--accent-light);color:var(--accent)}.badge-hard{background:var(--warm-light);color:var(--warm)}.top-nav{justify-content:space-between;align-items:center;margin-bottom:8px;padding:18px 0;display:flex}.logo{color:var(--primary-dark);letter-spacing:-.02em;font-size:21px;font-weight:800}.spinner{border:3px solid var(--border);border-top-color:var(--primary);border-radius:50%;width:28px;height:28px;animation:.8s linear infinite spin}@keyframes spin{to{transform:rotate(360deg)}}.center-screen{justify-content:center;align-items:center;min-height:60vh;display:flex}.error-text{color:#b3453a;margin-top:4px;font-size:14px}.hero{padding:8px 0 28px}.hero-title{color:var(--primary-dark);letter-spacing:-.03em;margin:0;font-size:32px;font-weight:800}.hero-sub{color:var(--text-muted);margin-top:6px;font-size:15px}.subject-grid{grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:18px;padding-bottom:40px;display:grid}.subject-card{background:var(--surface);border-radius:var(--radius);box-shadow:var(--shadow-sm);color:inherit;border:1px solid #1428210d;padding:22px;text-decoration:none;transition:transform .18s,box-shadow .18s;display:block;position:relative;overflow:hidden}.subject-card:hover{box-shadow:var(--shadow-lg);transform:translateY(-3px)}.subject-card:before{content:"";background:var(--card-accent,var(--primary));height:4px;position:absolute;top:0;left:0;right:0}.subject-icon{background:var(--card-accent-light,var(--primary-light));border-radius:14px;justify-content:center;align-items:center;width:48px;height:48px;margin-bottom:14px;font-size:26px;display:flex}.subject-code{letter-spacing:.05em;color:var(--card-accent,var(--primary));text-transform:uppercase;font-size:12px;font-weight:700}.subject-name{color:var(--text);margin-top:4px;font-size:16.5px;font-weight:700;line-height:1.35}.subject-status{color:var(--text-muted);align-items:center;gap:6px;margin-top:14px;font-size:13px;display:flex}.subject-status.available{color:var(--success);font-weight:600}.quiz-row{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:12px;display:flex}.quiz-row-meta{flex-wrap:wrap;align-items:center;gap:14px;display:flex}@media (width<=640px){.hero-title{font-size:26px}.quiz-row{flex-direction:column;align-items:stretch}.quiz-row .btn{width:100%}}