.letter-index {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    padding: 10px 5px;
    background-color: #f5f5f5;
    position: sticky;
    top: 0;
    z-index: 100;
}

.letter-index-item {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 1.2rem;
    height: 1.2rem;
    padding: 6px;
    text-align: center;
    margin: 2px;
    border-radius: 50%;
    background-color: #fff;
    color: var(--text-primary);
    font-size: var(--font-size-xs);
    text-decoration: none;
    font-weight: bold;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.letter-index-item:hover, .letter-index-item:active {
    background-color: #007bff;
    color: #fff;
}

/* 响应式调整 */
@media (max-width: 768px) {
    .letter-index-item {
        width: 20px;
        height: 20px;
        line-height: 20px;
        font-size: 12px;
    }
}