:root{--bg-0: #f2f6fb;--bg-1: #ffffff;--bg-2: #eaf0f8;--text-1: #0f172a;--text-2: #334155;--primary: #0b5fff;--primary-2: #0748c5;--ok: #0f9d58;--warn: #d14343;--border: #d7e0ee;--shadow: 0 10px 24px rgba(15, 23, 42, .08)}*{box-sizing:border-box}body{margin:0;font-family:Manrope,sans-serif;color:var(--text-1);background:radial-gradient(circle at top left,#dfeeff,#f8fbff 45%,#eef4fb)}.app-shell{min-height:100vh;display:grid;grid-template-columns:320px 1fr}.sidebar{background:linear-gradient(180deg,#0f274a,#123666);color:#f8fbff;padding:24px;display:flex;flex-direction:column;gap:16px}.brand h1{margin:4px 0 0;font-family:Space Grotesk,sans-serif}.brand h3{margin:0;font-family:Space Grotesk,sans-serif}.brand p{margin:4px 0 0}.eyebrow{margin:0;font-size:12px;letter-spacing:.08em;text-transform:uppercase;opacity:.8}.panel{background:#ffffff1f;border:1px solid rgba(255,255,255,.2);border-radius:14px;padding:14px}label{display:block;font-size:13px;margin-bottom:8px}select,button{font:inherit}select{width:100%;border-radius:10px;border:none;padding:10px}.stats{display:grid;gap:10px}.stat-item{display:flex;justify-content:space-between;font-size:14px}.progress-track{height:8px;border-radius:999px;background:#ffffff40}.progress-fill{height:100%;border-radius:inherit;background:#65a7ff}.actions{display:grid;gap:10px}.sidebar-footer{margin:6px 0 0;text-align:center;font-size:13px;opacity:.9}button{border:none;border-radius:10px;padding:10px 12px;cursor:pointer;transition:.2s ease}button:hover{transform:translateY(-1px)}button.secondary{background:#cfe1ff;color:#0a3fa8;font-weight:700}button.danger{background:#ffe8e8;color:#a82323}.content{padding:24px;display:grid;grid-template-rows:auto auto 1fr;gap:16px}.content-header{background:var(--bg-1);border:1px solid var(--border);border-radius:14px;padding:16px;display:flex;justify-content:space-between;align-items:center;box-shadow:var(--shadow)}.content-header h2{margin:0 0 4px}.content-header p{margin:0;color:var(--text-2)}.header-actions{display:flex;gap:8px}button.chip{background:var(--bg-2);color:#174177}button:disabled{cursor:not-allowed;opacity:.5;transform:none}.question-card{background:var(--bg-1);border:1px solid var(--border);border-radius:14px;padding:18px;box-shadow:var(--shadow)}.question-text{margin-top:0;font-size:1.08rem;line-height:1.5}.options{display:grid;gap:10px}.option-btn{width:100%;text-align:left;display:flex;align-items:flex-start;gap:10px;background:#f8fbff;border:1px solid var(--border)}.option-btn:disabled{cursor:not-allowed;opacity:1;color:var(--text-1);-webkit-text-fill-color:var(--text-1);-webkit-user-select:none;user-select:none}button.secondary:disabled{background:#d9ecff;color:#2859b8;opacity:1}.option-btn.selected{border-color:var(--primary);background:#e8f0ff}.option-btn.correct{border-color:var(--ok);background:#e8f7ef}.option-btn.wrong{border-color:var(--warn);background:#fdecec}.option-key{width:24px;height:24px;border-radius:6px;display:inline-flex;align-items:center;justify-content:center;background:#dde7f6;font-weight:700}.qa-footer{margin-top:14px;display:flex;align-items:center;gap:12px}.answer{margin:0;font-weight:700;color:#0f5d32}.navigator{background:var(--bg-1);border:1px solid var(--border);border-radius:14px;padding:14px;box-shadow:var(--shadow);display:grid;grid-template-columns:repeat(auto-fill,minmax(42px,1fr));gap:8px;align-content:start}.nav-item{background:#eef3fb;color:#244574;font-weight:600;padding:8px}.nav-item.active{background:var(--primary);color:#fff}.nav-item.done{border:1px solid #58a66f}.nav-item.right{background:#e8f7ef;color:#0f5d32;border:1px solid #58a66f}.nav-item.wrong{background:#fdecec;color:#8f1f1f;border:1px solid #d14343}@media (max-width: 920px){.app-shell{grid-template-columns:1fr}.sidebar{border-bottom-left-radius:18px;border-bottom-right-radius:18px}.content{padding:14px}.content-header{flex-direction:column;align-items:flex-start;gap:10px}.qa-footer{flex-direction:column;align-items:flex-start}}