/* 全局样式和变量 */
:root {
    --sidebar-width: 240px;
    --top-bar-height: 60px;
    --primary-color: #007bff;
    --background-color: #f4f7f9;
    --card-background: #ffffff;
    --text-color: #333;
    --border-color: #e0e0e0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column; /* 让页脚可以自然地排在 main 后面 */
    min-height: 100vh; /* 保证内容不足时页脚也在底部 */
}

/* 顶部导航栏 */
.top-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--top-bar-height);
    background-color: var(--card-background);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    display: flex;
    align-items: center;
    padding: 0 20px;
    z-index: 1000;
}

.menu-toggle {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    margin-right: 20px;
}

.site-title {
    margin: 0;
    font-size: 20px;
}

/* 侧边栏 */
.sidebar {
    width: var(--sidebar-width);
    height: 100vh;
    position: fixed;
    top: 0;
    left: 0;
    background-color: var(--card-background);
    border-right: 1px solid var(--border-color);
    padding-top: var(--top-bar-height);
    box-sizing: border-box;
    transition: transform 0.3s ease;
    z-index: 900;
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h2 {
    margin: 0;
    font-size: 18px;
}

.category-list {
    list-style: none;
    padding: 0;
    margin: 0;
    overflow-y: auto;
}

.category-list li a {
    display: block;
    padding: 15px 20px;
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: background-color 0.2s;
    border-left: 3px solid transparent;
}

.category-list li a:hover {
    background-color: #f0f0f0;
}

.category-list li a.active {
    background-color: #e9ecef;
    border-left-color: var(--primary-color);
    font-weight: bold;
}

/* 主内容区 */
.main-content {
    flex: 1;
    margin-top: var(--top-bar-height);
    margin-left: var(--sidebar-width);
    padding: 24px;
    transition: margin-left 0.3s ease;
}

/* 表情包网格 */
.gallery-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 24px;
}

.gallery-item {
    background-color: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    display: flex;
    flex-direction: column;
}

/* 图片容器，这是实现悬停效果的关键 */
.image-container {
    position: relative;
    overflow: hidden; /* 隐藏溢出的覆盖层 */
}

.gallery-item .meme-image {
    display: block;
    width: 100%;
    height: 220px;
    object-fit: contain;
    background-color: #f8f9fa;
    transition: transform 0.3s ease;
}

.gallery-item:hover .meme-image {
    transform: scale(1.05);
}

/* 文件名显示 */
.filename {
    padding: 12px 15px;
    font-size: 14px;
    word-break: break-all;
    text-align: center;
    margin-top: auto;
    border-top: 1px solid var(--border-color);
}

/* 悬浮下载条 (渐变效果) */
.image-overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 60px;
    background: linear-gradient(to top, rgba(0, 0, 0, 0.7), transparent);
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding: 0 15px;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.image-container:hover .image-overlay {
    opacity: 1;
    transform: translateY(0);
}

.download-link {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 5px;
    border-radius: 50%;
    transition: background-color 0.2s;
}

.download-link:hover {
    background-color: rgba(255, 255, 255, 0.2);
}

.download-icon {
    width: 22px;
    height: 22px;
}

/* --- 页脚样式修改 --- */
.site-footer {
    width: 100%;
    box-sizing: border-box; /* 保证 padding 不会影响宽度 */
    padding: 15px;
    background-color: #e9ecef;
    text-align: center;
    font-size: 14px;
    color: #6c757d;
    border-top: 1px solid var(--border-color);
    /* 移除 position:fixed 和相关属性 */
}


/* --- 侧边栏折叠逻辑 --- */
body.sidebar-collapsed .sidebar {
    transform: translateX(-100%);
}

body.sidebar-collapsed .main-content {
    margin-left: 0;
}


/* --- 新增：自定义右键菜单样式 --- */
.custom-context-menu {
    position: fixed;
    z-index: 2000;
    background-color: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 12px; /* 圆角样式 */
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    padding: 8px;
    width: 220px;
    font-size: 14px;
    /* 使用 fixed 后，菜单相对于视口，配合 clientX/clientY 定位更稳健 */
}

.context-menu-item {
    display: flex;
    align-items: center;
    padding: 10px 12px;
    cursor: pointer;
    border-radius: 8px;
}

.context-menu-item:hover {
    background-color: #f0f0f0;
}

.context-menu-icon {
    width: 16px;
    height: 16px;
    margin-right: 12px;
}

.context-menu-separator {
    height: 1px;
    background-color: var(--border-color);
    margin: 8px 0;
}


/* 移动端响应式设计 */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
    }
    
    body.sidebar-opened .sidebar {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
    }

    .gallery-container {
        grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
        gap: 15px;
    }

    .gallery-item .meme-image {
        height: 130px;
    }

    .image-overlay {
        opacity: 0.7;
        transform: translateY(0);
        height: 40px;
    }
    .download-icon {
        width: 18px;
        height: 18px;
    }
}