*{box-sizing:border-box}:root{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Open Sans,Helvetica Neue,sans-serif;line-height:1.5;font-weight:400;color:#213547;background-color:#f5f5f7;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}body{margin:0;min-width:320px;min-height:100vh}#root{min-height:100vh}a{color:#e94560;text-decoration:none}a:hover{text-decoration:underline}button{font-family:inherit}h1,h2,h3,h4,h5,h6,p{margin:0}.sync-button{padding:8px 16px;font-size:.875rem;font-weight:600;color:#fff;background:#e94560;border:none;border-radius:8px;cursor:pointer;transition:background .2s,transform .1s}.sync-button:hover:not(:disabled){background:#d13354}.sync-button:active:not(:disabled){transform:scale(.98)}.sync-button:disabled{background:#ccc;cursor:not-allowed}.sync-button__loading{display:inline-flex;align-items:center;gap:8px}.header{background:#fff;box-shadow:0 2px 8px #0000001a;position:sticky;top:0;z-index:100}.header__top{display:flex;justify-content:space-between;align-items:center;padding:12px 16px}.header__title{font-size:1.25rem;font-weight:700;color:#1a1a2e;margin:0}.header__nav{display:flex;border-top:1px solid #eee}.header__nav-link{flex:1;padding:12px;text-align:center;text-decoration:none;color:#666;font-weight:500;transition:color .2s,border-color .2s;border-bottom:2px solid transparent}.header__nav-link:hover{color:#e94560}.header__nav-link--active{color:#e94560;border-bottom-color:#e94560}.toast{position:fixed;bottom:80px;left:50%;transform:translate(-50%);padding:12px 24px;border-radius:8px;color:#fff;font-weight:500;box-shadow:0 4px 12px #0003;cursor:pointer;animation:toast-slide-up .3s ease;z-index:1000;max-width:90%;text-align:center}.toast--success{background:#2ecc71}.toast--error{background:#e74c3c}.toast--info{background:#3498db}@keyframes toast-slide-up{0%{opacity:0;transform:translate(-50%) translateY(20px)}to{opacity:1;transform:translate(-50%) translateY(0)}}.flashcard-item{background:#fff;border-radius:12px;padding:16px;box-shadow:0 2px 8px #0000001a;text-align:center}.flashcard-item--list{margin-bottom:12px}.flashcard-item--full{display:flex;flex-direction:column;justify-content:center;align-items:center;height:100%;padding:32px}.flashcard-item__chinese{font-size:2rem;font-weight:700;color:#1a1a2e;margin-bottom:8px}.flashcard-item--full .flashcard-item__chinese{font-size:3.5rem;margin-bottom:16px}.flashcard-item__pinyin{font-size:1.25rem;color:#e94560;margin-bottom:8px}.flashcard-item--full .flashcard-item__pinyin{font-size:1.75rem;margin-bottom:16px}.flashcard-item__english{font-size:1.1rem;color:#4a4a68}.flashcard-item--full .flashcard-item__english{font-size:1.5rem}.flashcard-item__source{font-size:.75rem;color:#9a9abb;margin-top:12px;padding-top:8px;border-top:1px solid #eee}.flashcard-list{padding:16px 16px 80px}.flashcard-list__empty{text-align:center;padding:48px 16px;color:#666}.flashcard-list__empty p{margin:8px 0}.flashcard-list__observer{height:20px;margin-top:16px}.flashcard-list__loading{text-align:center;color:#888;padding:16px}.lesson-filter{padding:0 16px;margin-bottom:16px}.lesson-filter__select{width:100%;padding:12px 16px;font-size:1rem;border:2px solid #e0e0e0;border-radius:8px;background:#fff;color:#333;cursor:pointer;appearance:none;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23666' d='M6 8L1 3h10z'/%3E%3C/svg%3E");background-repeat:no-repeat;background-position:right 16px center}.lesson-filter__select:focus{outline:none;border-color:#e94560}.random-mode{display:flex;flex-direction:column;height:calc(100vh - 120px);padding:16px;touch-action:pan-y;-webkit-user-select:none;user-select:none}.random-mode--loading,.random-mode--empty{justify-content:center;align-items:center;text-align:center;color:#666}.random-mode--empty p{margin:8px 0}.random-mode__card-container{flex:1;display:flex;align-items:center;justify-content:center;padding:16px 0}.random-mode__card-container .flashcard-item{width:100%;max-width:400px;min-height:300px}.random-mode__controls{display:flex;justify-content:space-between;align-items:center;padding:16px 0}.random-mode__nav-btn{padding:12px 24px;font-size:1rem;font-weight:600;border:none;border-radius:8px;cursor:pointer;transition:background .2s,transform .1s}.random-mode__nav-btn--prev{background:#e0e0e0;color:#333}.random-mode__nav-btn--prev:hover:not(:disabled){background:#d0d0d0}.random-mode__nav-btn--prev:disabled{opacity:.5;cursor:not-allowed}.random-mode__nav-btn--next{background:#e94560;color:#fff}.random-mode__nav-btn--next:hover{background:#d13354}.random-mode__nav-btn:active:not(:disabled){transform:scale(.98)}.random-mode__counter{font-size:1rem;color:#666;font-weight:500}.random-mode__swipe-hint{text-align:center;font-size:.75rem;color:#999;padding-bottom:16px}@media(min-width:768px){.random-mode__card-container .flashcard-item{max-width:500px;min-height:400px}}.app{min-height:100vh;background:#f5f5f7}.app__main{max-width:600px;margin:0 auto}