.nav-link {
    font-size: 16px;
    padding: 10px 15px;
    border-radius: 4px;
    transition: background-color 0.2s ease;
}

.nav-link:hover {
    background-color: #f8f9fa;
}

.nav-link i {
    margin-right: 8px;
}

.footer {
    position: fixed;
    bottom: 0;
    width: 100%;
}

.nav-active {
    background-color: #f5f5f5 !important; /* 例: 緑色 */
    color: #000000 !important; /* 白文字 */
    font-weight: bold; 
}