html, body {
    height: 100%;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
    overflow-x: hidden; /* 防止水平滚动条 */
}

.container {
    display: flex;
    height: 100vh; /* 确保容器高度填满视口 */
    min-height: 100%;
}

.menu {
    width: 25%;
    background-color: #333;
    color: #fff;
    padding: 10px 0; /* 减少顶部和底部的内边距 */
    box-sizing: border-box;
    position: sticky; /* 使用 sticky 使菜单在滚动时固定 */
    top: 0;
    height: 100vh;
    overflow-y: auto; /* 允许菜单内部滚动 */
    z-index: 1000; /* 确保菜单在最上层 */
}

.select-group {
    margin-bottom: 10px; /* 减少组之间的间距 */
}

.menu label {
    display: block;
    padding: 8px 15px; /* 减少标签的内边距 */
    text-align: center;
    font-size: 1em; /* 调整字体大小 */
    cursor: pointer;
    transition: background-color 0.3s;
}

.menu select {
    width: 100%;
    padding: 8px;
    border: none;
    border-radius: 4px;
    appearance: none;
    background-color: #575757;
    color: #fff;
    cursor: pointer;
    transition: background-color 0.3s;
}

.menu select:hover,
.menu select:focus {
    background-color: #777;
}

.content-container {
    width: 75%;
    padding: 20px;
    box-sizing: border-box;
    overflow-y: auto; /* 允许内容区域滚动 */
    flex-grow: 1; /* 让内容区域占据剩余空间 */
}

.content {
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    padding: 20px;
}

.content-divider {
    border: 0;
    height: 1px;
    background: #ccc;
    margin: 20px 0;
}

@media (max-width: 768px) {
    .container {
        flex-direction: column;
    }

    .menu, .content-container {
        width: 100%;
        position: relative; /* 取消固定定位 */
    }

    .menu {
        height: auto; /* 高度由内容决定 */
        overflow-y: visible; /* 取消内部滚动 */
    }

    .content-container {
        margin-left: 0;
    }
}