/*
 * 纯CSS实现PC端导航菜单示例
 * 这个文件展示了如何仅使用CSS实现完整的导航菜单功能
 * 包括下拉菜单、动画效果和响应式设计
 */

/* === 基础导航容器样式 === */
#css-only-nav-container {
    position: relative;
    z-index: 100000;
}

/* === 主菜单样式 === */
.css-only-nav {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    position: relative;
}

/* === 菜单项样式 === */
.css-only-nav > .menu-item {
    position: relative;
    margin: 0 5px;
}

.css-only-nav > .menu-item > a {
    display: block;
    padding: 15px 20px;
    text-decoration: none;
    color: #333;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    z-index: 2;
}

/* 菜单项悬停效果 */
.css-only-nav > .menu-item:hover > a {
    color: #0073aa;
}

/* === 子菜单基础样式 === */
.css-only-nav .sub-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    margin: 0;
    padding: 10px 0;
    background: white;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    list-style: none;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
    z-index: 100001;
    border-radius: 4px;
    border-top: 3px solid #0073aa;
}

/* 悬停显示子菜单 - 核心实现 */
.css-only-nav .menu-item:hover > .sub-menu,
.css-only-nav .menu-item:focus-within > .sub-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

/* === 子菜单项样式 === */
.css-only-nav .sub-menu > .menu-item {
    position: relative;
}

.css-only-nav .sub-menu > .menu-item > a {
    display: block;
    padding: 12px 20px;
    color: #555;
    text-decoration: none;
    transition: background-color 0.2s ease, color 0.2s ease;
    white-space: nowrap;
}

/* 子菜单项悬停效果 */
.css-only-nav .sub-menu > .menu-item:hover > a {
    background-color: #f5f5f5;
    color: #0073aa;
    padding-left: 22px;
}

/* === 多级子菜单样式 === */
.css-only-nav .sub-menu .sub-menu {
    top: 0;
    left: 100%;
    margin-left: 5px;
    border-top: 3px solid #0099cc;
}

/* 为带有子菜单的菜单项添加箭头 */
.css-only-nav .menu-item-has-children > a:after {
    content: '▾';
    margin-left: 8px;
    font-size: 12px;
    color: inherit;
}

/* 二级菜单的箭头方向调整 */
.css-only-nav .sub-menu .menu-item-has-children > a:after {
    content: '▸';
    float: right;
    margin-left: 0;
    margin-right: 5px;
}

/* === Sticky导航适配 === */
.wmmb-primary-sticky-header-active #css-only-nav-container {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        transform: translateY(-100%);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

/* Sticky状态下的子菜单样式 */
.wmmb-primary-sticky-header-active .css-only-nav .sub-menu {
    position: fixed;
    transform: none;
}

/* === 可访问性优化 === */
.css-only-nav .menu-item > a:focus {
    outline: 2px solid #0073aa;
    outline-offset: 2px;
}

/* 使用focus-within优化键盘导航 */
.css-only-nav .menu-item:focus-within > a {
    color: #0073aa;
    background-color: #f5f5f5;
}

/* === 动画效果变体 === */
/* 淡入效果 */
.css-only-nav.animation-fade .sub-menu {
    transition: opacity 0.4s ease, visibility 0.4s ease;
    transform: none;
}

/* 滑入效果 */
.css-only-nav.animation-slide .sub-menu {
    transition: transform 0.3s ease, opacity 0.3s ease, visibility 0.3s ease;
}

/* 弹跳效果 */
.css-only-nav.animation-bounce .sub-menu {
    transition: transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275), 
                opacity 0.3s ease, 
                visibility 0.3s ease;
}

.css-only-nav.animation-bounce .menu-item:hover > .sub-menu,
.css-only-nav.animation-bounce .menu-item:focus-within > .sub-menu {
    transform: translateY(0) scale(1);
}

/* === 响应式设计 === */
@media (max-width: 921px) {
    .css-only-nav {
        display: block;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease;
    }
    
    /* 移动端菜单展开状态 */
    .css-only-nav.expanded {
        max-height: 500px;
    }
    
    .css-only-nav > .menu-item {
        margin: 0;
    }
    
    .css-only-nav > .menu-item > a {
        padding: 12px 15px;
        border-bottom: 1px solid #eee;
    }
    
    /* 移动端子菜单样式 */
    .css-only-nav .sub-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        padding-left: 20px;
        padding-top: 0;
        padding-bottom: 0;
        background: transparent;
        border: none;
    }
    
    .css-only-nav .sub-menu > .menu-item > a {
        padding: 8px 15px;
        border-bottom: 1px solid #f5f5f5;
    }
    
    /* 移动端二级子菜单样式 */
    .css-only-nav .sub-menu .sub-menu {
        position: static;
        margin-left: 0;
        padding-left: 15px;
    }
    
    /* 移动端汉堡菜单按钮 */
    .mobile-menu-toggle {
        display: block;
        padding: 15px;
        background: #0073aa;
        color: white;
        border: none;
        cursor: pointer;
        width: 100%;
        text-align: left;
        font-size: 16px;
        font-weight: bold;
    }
}

@media (min-width: 922px) {
    /* 桌面端隐藏汉堡菜单 */
    .mobile-menu-toggle {
        display: none;
    }
}

/* === 高级样式选项 === */
/* 深色主题 */
.css-only-nav.dark-theme {
    background: #333;
}

.css-only-nav.dark-theme > .menu-item > a {
    color: #fff;
}

.css-only-nav.dark-theme > .menu-item:hover > a {
    color: #00bcd4;
}

.css-only-nav.dark-theme .sub-menu {
    background: #444;
    border-top-color: #00bcd4;
}

.css-only-nav.dark-theme .sub-menu > .menu-item > a {
    color: #ddd;
}

.css-only-nav.dark-theme .sub-menu > .menu-item:hover > a {
    background-color: #555;
    color: #00bcd4;
}

/* 下划线动画效果 */
.css-only-nav.underline-effect > .menu-item > a {
    position: relative;
}

.css-only-nav.underline-effect > .menu-item > a:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: #0073aa;
    transition: width 0.3s ease;
}

.css-only-nav.underline-effect > .menu-item:hover > a:after,
.css-only-nav.underline-effect > .menu-item:focus-within > a:after {
    width: 100%;
}

/* 圆角样式 */
.css-only-nav.rounded-corners > .menu-item > a {
    border-radius: 6px;
}

.css-only-nav.rounded-corners .sub-menu {
    border-radius: 8px;
}