*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;background:#f5f7fa;color:#1a1a2e;min-height:100vh}.container{max-width:900px;margin:0 auto;padding:2rem}h1{margin-bottom:1.5rem;color:#16213e}h2{margin-bottom:1rem;color:#0f3460}button{background:#0f3460;color:#fff;border:none;padding:.7rem 1.5rem;border-radius:6px;cursor:pointer;font-size:.95rem}button:hover{background:#16213e}button:disabled{background:#999;cursor:not-allowed}button.secondary{background:#e94560}button.secondary:hover{background:#c23152}input,select{padding:.7rem;border:1px solid #ddd;border-radius:6px;font-size:1rem;width:100%;margin-bottom:.8rem}.card{background:#fff;border-radius:10px;padding:1.5rem;margin-bottom:1rem;box-shadow:0 2px 8px #00000014}.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:1rem}.auth-page{display:flex;align-items:center;justify-content:center;min-height:100vh}.auth-form{background:#fff;padding:2.5rem;border-radius:12px;box-shadow:0 4px 20px #0000001a;width:100%;max-width:400px}.flashcard{background:#fff;border-radius:12px;padding:3rem 2rem;text-align:center;min-height:250px;display:flex;align-items:center;justify-content:center;box-shadow:0 4px 20px #0000001a;cursor:pointer;font-size:1.2rem;transition:transform .2s}.flashcard:hover{transform:scale(1.02)}.flashcard.flipped{background:#e8f4fd}.progress{display:flex;gap:.5rem;align-items:center;margin-bottom:1rem}.nav{display:flex;justify-content:space-between;align-items:center;margin-bottom:2rem;padding-bottom:1rem;border-bottom:1px solid #eee}.error{color:#e94560;margin-bottom:.5rem;font-size:.9rem}.success{color:#0f9b58;margin-bottom:.5rem}.badge{display:inline-block;background:#e8f4fd;color:#0f3460;padding:.2rem .6rem;border-radius:4px;font-size:.8rem;margin-right:.5rem}.quiz-option{display:block;width:100%;text-align:left;background:#fff;color:#1a1a2e!important;border:2px solid #ddd;margin-bottom:.5rem;padding:1rem;border-radius:8px;cursor:pointer;font-size:.95rem}.quiz-option:hover{border-color:#0f3460}.quiz-option.correct{border-color:#0f9b58;background:#e8fdf0}.quiz-option.wrong{border-color:#e94560;background:#fde8ec}.quiz-option.selected{border-color:#0f3460;background:#e8f4fd}.actions{display:flex;gap:.5rem;margin-top:1rem;flex-wrap:wrap}.upload-area{border:2px dashed #ddd;border-radius:12px;padding:2rem;text-align:center;margin-bottom:1rem}.spinner{display:inline-block;width:20px;height:20px;border:3px solid #ddd;border-top-color:#0f3460;border-radius:50%;animation:spin .8s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}