.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #f8f9fa;
    padding: 10px 20px;
    border-bottom: 1px solid #ddd;
    font-family: sans-serif;
    position: relative;
}

.nav-left, .nav-right {
    display: flex;
    align-items: center;
    gap: 15px;
}

.navbar a, .navbar .username {
    text-decoration: none;
    color: #0077cc;
    transition: color 0.3s;
    cursor: pointer;
}

.navbar a:hover, .navbar .username:hover {
    color: #005fa3;
}

/* 暗黑模式 */
body.dark .navbar {
    background: #222;
    border-bottom: 1px solid #444;
}
body.dark .navbar a,
body.dark .navbar .username {
    color: #4da6ff;
}
body.dark .navbar a:hover,
body.dark .navbar .username:hover {
    color: #3399ff;
}

/* 下拉菜单 */
.dropdown {
    position: relative;
}
.dropdown-content {
    display: none;
    position: absolute;
    right: 0;
    top: 100%;
    background: #fff;
    min-width: 140px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
    border-radius: 5px;
    z-index: 1000;
}
.dropdown-content a {
    display: block;
    padding: 10px 15px;
    color: #0077cc;
}
.dropdown-content a:hover {
    background: #f2f2f2;
}
.dropdown:hover .dropdown-content {
    display: block;
}
/* 暗黑模式下拉 */
body.dark .dropdown-content {
    background: #333;
}
body.dark .dropdown-content a {
    color: #4da6ff;
}
body.dark .dropdown-content a:hover {
    background: #444;
}

/* 汉堡按钮 */
.hamburger {
    display: none;
    font-size: 22px;
    cursor: pointer;
}

@media (max-width: 600px) {

    h1 {
        margin-top: 20%;
    }

    .nav-left, .nav-right {
        display: none;
        flex-direction: column;
        background: #f8f9fa;
        position: absolute;
        left: 0;
        right: 0;
        padding: 10px 0;
        border-top: 1px solid #ddd;
    }
    .nav-left {
        top: 100%;
        display: flex; /* 示例：默认展开左侧？根据逻辑调整 */
    }
    .nav-right {
        top: auto; /* JS 会覆盖这个值 */
    }
    body.nav-open .nav-left,
    body.nav-open .nav-right {
        display: flex;
    }
    .hamburger {
        display: block;
    }

    /* 暗黑模式 */
    body.dark .nav-left,
    body.dark .nav-right {
        background: #222;
        border-top: 1px solid #444;
    }
}