:root{--dark-bg: #121212;--dark-text: #f1f1f1;--dark-card-bg: #222;--dark-border: #555;--cyberpunk-bg: #0f0f1e;--cyberpunk-text: #00ffea;--cyberpunk-glow: #00ffe5;--cyberpunk-accent: #ff00ff;--button-bg: #444;--button-hover: #666;--transition: all .3s ease}*{margin:0;padding:0;box-sizing:border-box}.app-container{min-height:100vh;width:100%;font-family:Inter,sans-serif;transition:var(--transition);background:#1a1a3b;display:flex;flex-direction:column;align-items:center;justify-content:flex-start;overflow-x:hidden}.app-container.dark{background:var(--dark-bg);color:var(--dark-text)}.app-container.cyberpunk{background:linear-gradient(135deg,var(--cyberpunk-bg) 0%,#1a1a3b 100%);color:var(--cyberpunk-text);text-shadow:0 0 5px var(--cyberpunk-glow),0 0 10px var(--cyberpunk-accent)}.app{text-align:center;padding:1.5rem;width:100%;max-width:1200px;margin:0 auto}button{margin:.5rem;padding:.75rem 1.5rem;border:none;border-radius:8px;cursor:pointer;font-weight:600;transition:var(--transition);background:var(--button-bg);color:var(--dark-text)}button:hover{background:var(--button-hover);transform:translateY(-2px);box-shadow:0 4px 8px #0003}button:active{transform:translateY(0);box-shadow:none}.theme-toggle{background:linear-gradient(45deg,#3b82f6,#60a5fa);color:#fff;padding:.75rem 1.25rem;border-radius:50px;position:relative;overflow:hidden}.theme-toggle:before{content:"";position:absolute;top:0;left:-100%;width:100%;height:100%;background:#fff3;transition:left .4s ease}.theme-toggle:hover:before{left:0}.flashcards .cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:1rem;padding:1rem;justify-items:center}.card{width:100%;max-width:200px;height:140px;perspective:1000px;cursor:pointer;position:relative;border-radius:12px;transition:transform .3s ease}.card:hover{transform:scale(1.05)}.card .front,.card .back{position:absolute;width:100%;height:100%;backface-visibility:hidden;display:flex;align-items:center;justify-content:center;border-radius:12px;padding:1rem;font-size:.9rem;font-weight:500;transition:transform .6s ease,box-shadow .3s ease}.card .front{background:var(--dark-card-bg);color:var(--dark-text);box-shadow:0 4px 12px #0000004d}.card .back{background:linear-gradient(45deg,#1e40af,#3b82f6);color:#fff;transform:rotateY(180deg)}.card.flipped .front{transform:rotateY(180deg)}.card.flipped .back{transform:rotateY(0);box-shadow:0 4px 12px #0000004d}.app-container.cyberpunk .card .front{background:#1a1a3b;border:1px solid var(--cyberpunk-glow);box-shadow:0 0 15px var(--cyberpunk-glow)}.app-container.cyberpunk .card .back{background:linear-gradient(45deg,var(--cyberpunk-accent),#ff0066);text-shadow:0 0 8px var(--cyberpunk-glow)}footer{margin-top:2rem;padding:1.5rem;border-top:1px solid var(--dark-border);font-size:.9rem;text-align:center;background:linear-gradient(to top,rgba(0,0,0,.2),transparent)}.app-container.cyberpunk footer{border-top:1px solid var(--cyberpunk-glow);text-shadow:0 0 5px var(--cyberpunk-glow)}@media (max-width: 768px){.app{padding:1rem}.flashcards .cards{grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:.75rem}.card{max-width:160px;height:120px;font-size:.8rem}button{padding:.75rem 1.25rem;font-size:1rem;width:100%;border-radius:10px}.theme-toggle{padding:.6rem 1rem;font-size:.9rem;width:auto}footer{font-size:.8rem;padding:1rem}}@media (max-width: 480px){.flashcards .cards{grid-template-columns:1fr;gap:1rem}.card{max-width:100%;height:140px;font-size:.9rem;margin:0 auto}.app{padding:.75rem}button{font-size:1rem;padding:.9rem;width:100%}.theme-toggle{font-size:.9rem;padding:.6rem 1rem}footer{font-size:.8rem;padding:1rem}}