:root{--primary: #4ECDC4;--secondary: #FF6B6B;--accent: #FFE66D;--bg-start: #667eea;--bg-end: #764ba2}body{margin:0;font-family:system-ui,-apple-system,PingFang SC,sans-serif;-webkit-font-smoothing:antialiased;background-color:#f0f9ff}.bg-app-gradient{background:linear-gradient(135deg,var(--bg-start) 0%,var(--bg-end) 100%);background-attachment:fixed}.glass-panel{background:#fffffff2;backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);border:1px solid rgba(255,255,255,.3);box-shadow:0 8px 32px #0000001a;border-radius:20px}.btn-primary{background:linear-gradient(135deg,#4ecdc4,#38b0a8);color:#fff;font-weight:600;border-radius:12px;border:none;box-shadow:0 4px 12px #4ecdc44d;transition:all .2s ease;cursor:pointer}.btn-primary:hover{box-shadow:0 6px 16px #4ecdc480;transform:translateY(-2px)}.btn-secondary{background:#ffffffe6;color:#667eea;font-weight:600;border-radius:12px;border:none;box-shadow:0 4px 12px #0000000d;transition:all .2s ease;cursor:pointer}.btn-secondary:hover{background:#fff;transform:translateY(-2px);box-shadow:0 6px 16px #0000001a}.icon-btn{background:#fff3;-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px);border:none;border-radius:8px;width:32px;height:32px;display:flex;align-items:center;justify-content:center;color:#fff;cursor:pointer;transition:all .2s}.icon-btn:hover{background:#ffffff4d;transform:scale(1.05)}.topic-card{border-radius:16px;padding:16px;box-shadow:0 8px 24px #0000001a;transition:all .2s cubic-bezier(.175,.885,.32,1.275);position:relative;overflow:hidden;-webkit-tap-highlight-color:transparent}.topic-card:before{content:"";position:absolute;top:-50%;right:-50%;width:100%;height:100%;background:radial-gradient(circle,rgba(255,255,255,.2) 0%,transparent 70%);transform:rotate(45deg)}.topic-card:hover{transform:translateY(-4px);box-shadow:0 12px 32px #00000026}.topic-card:active{transform:scale(.95)}.quiz-option{width:100%;padding:12px 16px;border-radius:12px;background:#fff;border:2px solid #e5e7eb;color:#4a5568;font-weight:500;display:flex;justify-content:center;align-items:center;cursor:pointer;transition:all .2s;position:relative}.quiz-option:hover:not(:disabled){border-color:#667eea;background:#f8faff}.quiz-option.selected{border-color:#667eea;background:#f0f4ff;box-shadow:0 0 0 3px #667eea26}.quiz-option.correct{border-color:#10b981;background:#ecfdf5;color:#065f46}.quiz-option.wrong{border-color:#ef4444;background:#fef2f2;color:#991b1b}.font-handwriting{font-family:system-ui,-apple-system,sans-serif}::-webkit-scrollbar{width:6px}::-webkit-scrollbar-track{background:transparent}::-webkit-scrollbar-thumb{background:#ffffff4d;border-radius:3px}::-webkit-scrollbar-thumb:hover{background:#ffffff80}