*{margin:0;padding:0;box-sizing:border-box}body{font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;background:#f5f5f0;color:#333}.app,body{min-height:100vh}.app{display:flex}.sidebar{width:260px;background:#1a1a2e;color:#fff;padding:20px;flex-shrink:0;overflow-y:auto}.sidebar h2{font-size:1.3rem;margin-bottom:8px;color:#e0e0e0}.sidebar .subtitle{font-size:.75rem;color:#888;margin-bottom:20px}.sidebar-item{display:flex;justify-content:space-between;align-items:center;padding:10px 12px;margin-bottom:4px;border-radius:8px;cursor:pointer;transition:background .2s;font-size:.9rem}.sidebar-item:hover{background:rgba(255,255,255,.1)}.sidebar-item.active{background:#c0392b}.sidebar-item .badge{background:rgba(255,255,255,.2);padding:2px 8px;border-radius:12px;font-size:.75rem}.main{flex:1 1;padding:24px 32px;overflow-y:auto}.main header{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px}.main header h1{font-size:1.5rem;color:#1a1a2e}.btn-add{background:#c0392b;color:#fff;border:none;padding:10px 20px;border-radius:8px;cursor:pointer;font-size:.9rem;transition:background .2s}.btn-add:hover{background:#a93226}.section-filters{display:flex;gap:8px;margin-bottom:20px;flex-wrap:wrap}.section-btn{background:#e0e0e0;border:none;padding:6px 14px;border-radius:16px;cursor:pointer;font-size:.8rem;transition:all .2s}.section-btn:hover{background:#ccc}.section-btn.active{background:#c0392b;color:#fff}.card-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));grid-gap:16px;gap:16px}.flashcard{perspective:800px;height:200px;cursor:pointer}.flashcard-inner{position:relative;width:100%;height:100%;transition:transform .6s;transform-style:preserve-3d}.flashcard.flipped .flashcard-inner{transform:rotateY(180deg)}.flashcard-back,.flashcard-front{position:absolute;width:100%;height:100%;-webkit-backface-visibility:hidden;backface-visibility:hidden;border-radius:12px;padding:16px;display:flex;flex-direction:column;box-shadow:0 2px 8px rgba(0,0,0,.1)}.flashcard-front{background:#fff}.flashcard-back{background:#1a1a2e;color:#fff;transform:rotateY(180deg)}.flashcard-section{font-size:.7rem;color:#888;margin-bottom:4px}.flashcard-japanese{font-size:1.8rem;font-weight:700;flex:1 1;display:flex;align-items:center;justify-content:center}.flashcard-reading{font-size:.85rem;color:#666;text-align:center}.flashcard-back .meaning{font-size:1.1rem;flex:1 1;display:flex;align-items:center;justify-content:center;text-align:center}.flashcard-back .example{font-size:.75rem;color:#aaa;text-align:center;margin-top:8px}.flashcard-actions{display:flex;gap:8px;justify-content:flex-end;margin-top:8px}.flashcard-actions button{background:none;border:1px solid rgba(255,255,255,.3);color:#fff;padding:4px 10px;border-radius:4px;cursor:pointer;font-size:.75rem;transition:background .2s}.flashcard-actions button:hover{background:rgba(255,255,255,.15)}.flashcard-actions button.delete:hover{background:#c0392b}.modal-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(0,0,0,.5);display:flex;align-items:center;justify-content:center;z-index:100}.modal{background:#fff;border-radius:12px;padding:24px;width:95vw;max-width:500px;max-height:90vh;overflow-y:auto}.modal h2{margin-bottom:16px;color:#1a1a2e}.modal label{display:block;margin-bottom:4px;font-size:.85rem;color:#555}.modal input,.modal textarea{width:100%;padding:8px 12px;border:1px solid #ddd;border-radius:6px;margin-bottom:12px;font-size:.9rem;font-family:inherit}.modal textarea{resize:vertical;min-height:60px}.modal-buttons{display:flex;gap:8px;justify-content:flex-end;margin-top:8px}.modal-buttons button{padding:8px 20px;border-radius:6px;border:none;cursor:pointer;font-size:.9rem}.modal-buttons .btn-save{background:#c0392b;color:#fff}.modal-buttons .btn-cancel{background:#e0e0e0}.toast{position:fixed;bottom:20px;right:20px;background:#2ecc71;color:#fff;padding:12px 24px;border-radius:8px;font-size:.9rem;z-index:200;animation:slideIn .3s ease-out}@keyframes slideIn{0%{transform:translateY(20px);opacity:0}to{transform:translateY(0);opacity:1}}.framework-badge{font-size:.65rem;background:rgba(255,255,255,.15);padding:2px 8px;border-radius:8px;margin-top:12px;text-align:center;color:#888}