@import"https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;600&display=swap";:root{--font-sans: "Plus Jakarta Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;--font-mono: "JetBrains Mono", monospace;--bg-primary: #f8fafc;--bg-secondary: #ffffff;--bg-card: #ffffff;--bg-card-hover: #f1f5f9;--bg-glass: rgba(255, 255, 255, .92);--border-color: #e2e8f0;--border-active: #2563eb;--text-primary: #0f172a;--text-secondary: #475569;--text-muted: #94a3b8;--accent-primary: #2563eb;--accent-primary-hover: #1d4ed8;--accent-gradient: linear-gradient(135deg, #1e3a8a 0%, #2563eb 60%, #3b82f6 100%);--accent-gradient-warm: linear-gradient(135deg, #f59e0b 0%, #ea580c 100%);--accent-gradient-emerald: linear-gradient(135deg, #059669 0%, #10b981 100%);--success: #10b981;--success-bg: rgba(16, 185, 129, .1);--danger: #ef4444;--danger-bg: rgba(239, 68, 68, .1);--warning: #f59e0b;--warning-bg: rgba(245, 158, 11, .1);--info: #2563eb;--shadow-sm: 0 1px 3px rgba(15, 23, 42, .05), 0 1px 2px rgba(15, 23, 42, .03);--shadow-md: 0 4px 16px -2px rgba(15, 23, 42, .08), 0 2px 6px -1px rgba(15, 23, 42, .04);--shadow-lg: 0 12px 32px -4px rgba(15, 23, 42, .1), 0 4px 12px -2px rgba(15, 23, 42, .05);--shadow-glow: 0 0 25px rgba(37, 99, 235, .18);--radius-sm: 8px;--radius-md: 14px;--radius-lg: 20px;--radius-full: 9999px;--safe-bottom: env(safe-area-inset-bottom, 0px)}.dark{--bg-primary: #0a1120;--bg-secondary: #0f1a30;--bg-card: rgba(18, 30, 52, .9);--bg-card-hover: rgba(28, 46, 78, .95);--bg-glass: rgba(10, 17, 32, .88);--border-color: rgba(255, 255, 255, .09);--border-active: rgba(96, 165, 250, .5);--text-primary: #f8fafc;--text-secondary: #94a3b8;--text-muted: #64748b;--accent-primary: #3b82f6;--accent-primary-hover: #60a5fa;--accent-gradient: linear-gradient(135deg, #2563eb 0%, #60a5fa 100%);--shadow-sm: 0 2px 8px rgba(0, 0, 0, .3);--shadow-md: 0 8px 24px -4px rgba(0, 0, 0, .45);--shadow-lg: 0 16px 36px -6px rgba(0, 0, 0, .6);--shadow-glow: 0 0 25px rgba(59, 130, 246, .25)}*{box-sizing:border-box;margin:0;padding:0;-webkit-tap-highlight-color:transparent}body{font-family:var(--font-sans);background-color:var(--bg-primary);color:var(--text-primary);min-height:100vh;overflow-x:hidden;line-height:1.5;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;transition:background-color .25s ease,color .25s ease}::-webkit-scrollbar{width:6px;height:6px}::-webkit-scrollbar-track{background:transparent}::-webkit-scrollbar-thumb{background:var(--border-color);border-radius:var(--radius-full)}::-webkit-scrollbar-thumb:hover{background:var(--text-muted)}.app-container{display:flex;min-height:100vh;width:100%;position:relative}.sidebar{width:260px;background:var(--bg-secondary);border-right:1px solid var(--border-color);display:flex;flex-direction:column;flex-shrink:0;position:sticky;top:0;height:100vh;z-index:40;box-shadow:var(--shadow-sm)}.main-content{flex:1;display:flex;flex-direction:column;min-width:0;padding-bottom:calc(70px + var(--safe-bottom))}@media (min-width: 769px){.main-content{padding-bottom:30px}}.mobile-nav{display:none;position:fixed;bottom:0;left:0;right:0;height:calc(64px + var(--safe-bottom));padding-bottom:var(--safe-bottom);background:var(--bg-glass);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);border-top:1px solid var(--border-color);z-index:50;justify-content:space-around;align-items:center}@media (max-width: 768px){.sidebar{display:none}.mobile-nav{display:flex}}.app-header{position:sticky;top:0;z-index:30;background:var(--bg-glass);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);border-bottom:1px solid var(--border-color);padding:12px 20px;display:flex;align-items:center;justify-content:space-between;box-shadow:0 1px 4px #00000008}.card{background:var(--bg-card);backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);border:1px solid var(--border-color);border-radius:var(--radius-md);box-shadow:var(--shadow-sm);transition:all .2s cubic-bezier(.4,0,.2,1)}.card:hover{border-color:var(--border-active);box-shadow:var(--shadow-md)}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:10px 18px;font-size:.92rem;font-weight:600;font-family:inherit;border-radius:var(--radius-md);border:none;cursor:pointer;transition:all .18s ease;-webkit-user-select:none;user-select:none}.btn:active{transform:scale(.98)}.btn-primary{background:var(--accent-gradient);color:#fff;box-shadow:0 4px 14px #2563eb4d}.btn-primary:hover{box-shadow:0 6px 20px #2563eb73;transform:translateY(-1px)}.btn-secondary{background:var(--bg-card);color:var(--text-primary);border:1px solid var(--border-color);box-shadow:var(--shadow-sm)}.btn-secondary:hover{background:var(--bg-card-hover);border-color:var(--text-muted)}.btn-success{background:var(--accent-gradient-emerald);color:#fff;box-shadow:0 4px 14px #10b98147}.btn-icon{width:40px;height:40px;padding:0;border-radius:var(--radius-full);display:inline-flex;align-items:center;justify-content:center}.badge{display:inline-flex;align-items:center;gap:4px;padding:4px 10px;font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:.04em;border-radius:var(--radius-full)}.flashcard-wrapper{perspective:1200px;width:100%;max-width:520px;min-height:320px;margin:0 auto}.flashcard-inner{position:relative;width:100%;min-height:320px;text-align:center;transition:transform .6s cubic-bezier(.4,0,.2,1);transform-style:preserve-3d;cursor:pointer}.flashcard-inner.flipped{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{position:absolute;width:100%;height:100%;-webkit-backface-visibility:hidden;backface-visibility:hidden;border-radius:var(--radius-lg);padding:32px 24px;display:flex;flex-direction:column;justify-content:space-between;border:1px solid var(--border-color);box-shadow:var(--shadow-lg)}.flashcard-front{background:var(--bg-card)}.flashcard-back{background:linear-gradient(145deg,#1e3a8a,#0f2942);color:#fff;transform:rotateY(180deg);border-color:#3b82f666}@keyframes pulseGlow{0%,to{box-shadow:0 0 15px #2563eb33}50%{box-shadow:0 0 30px #2563eb73}}@keyframes slideUp{0%{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}.animate-slide-up{animation:slideUp .3s cubic-bezier(.16,1,.3,1) forwards}.option-item{display:flex;align-items:center;gap:14px;padding:14px 18px;border-radius:var(--radius-md);background:var(--bg-card);border:1.5px solid var(--border-color);cursor:pointer;transition:all .18s ease;-webkit-user-select:none;user-select:none}.option-item:hover{background:var(--bg-card-hover);border-color:var(--border-active);transform:translateY(-1px)}.option-item.selected{background:#2563eb14;border-color:var(--accent-primary);box-shadow:0 0 16px #2563eb2e}.dark .option-item.selected{background:#3b82f62e}.option-item.correct{background:var(--success-bg);border-color:var(--success);color:#059669}.dark .option-item.correct{color:#10b981}.option-item.incorrect{background:var(--danger-bg);border-color:var(--danger);color:#dc2626}.dark .option-item.incorrect{color:#ef4444}.code-box{font-family:var(--font-mono);background:#0f172a;border:1px solid rgba(255,255,255,.12);border-radius:var(--radius-sm);padding:14px 16px;font-size:.88rem;color:#38bdf8;overflow-x:auto;margin:12px 0}