* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Segoe UI", "Microsoft Yahei", sans-serif;
}

body {
    background-color: #f0f4f8;
    color: #333;
    line-height: 1.6;
}

/* 顶部导航栏 */
header {
    background: #1f4068;
    color: #fff;
    padding: 1.5rem 2rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.15);
    position: sticky;
    top: 0;
    z-index: 99;
}

.header-wrap {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.site-title h1 {
    font-size: 2rem;
    letter-spacing: 1px;
}

.author {
    margin-top: 0.5rem;
    font-size: 1rem;
    opacity: 0.85;
}

.bilibili-link {
    background: #fb7299;
    color: #fff;
    text-decoration: none;
    padding: 0.6rem 1.2rem;
    border-radius: 6px;
    transition: 0.3s;
    font-weight: 500;
    margin-right: 10px;
}

.bilibili-link:hover {
    background: #f85a87;
    transform: scale(1.05);
}

/* GitHub 链接样式 */
.github-link {
    background: #24292f;
    color: #fff;
    text-decoration: none;
    padding: 0.6rem 1.2rem;
    border-radius: 6px;
    transition: 0.3s;
    font-weight: 500;
}
.github-link:hover {
    background: #373e47;
    transform: scale(1.05);
}

/* 左侧固定导航 - 带滚动支持 + 过渡动画 */
.side-nav {
    position: fixed;
    left: 20px;
    top: 120px;
    bottom: 20px;
    background: #fff;
    padding: 1.2rem 1.5rem;
    border-radius: 10px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.1);
    width: 250px;
    z-index: 98;
    overflow-y: auto;
    overflow-x: hidden;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

/* 侧边栏隐藏样式 */
.side-nav.hidden {
    transform: translateX(-280px);
    opacity: 0;
    pointer-events: none;
}

/* 美化滚动条 */
.side-nav::-webkit-scrollbar {
    width: 6px;
}
.side-nav::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 3px;
}
.side-nav::-webkit-scrollbar-track {
    background: transparent;
}

.side-nav h4 {
    color: #1f4068;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid #eee;
}

.side-nav ul {
    list-style: none;
}

.side-nav li {
    margin: 0.4rem 0;
}

/* ========== 左侧大类菜单样式（加深背景） ========== */
.side-nav a.parent-item {
    background-color: #e8f0fc;
    color: #1f4068;
    text-decoration: none;
    padding: 0.5rem 0.8rem;
    display: block;
    border-radius: 6px;
    transition: background 0.2s;
    cursor: pointer;
    font-weight: 500;
}
.side-nav a.parent-item:hover {
    background-color: #d0e1f7;
}

/* ========== 子菜单容器样式 ========== */
.sub-menu {
    display: none;
    margin-left: 12px;
    border-left: 1px dashed #ccc;
    padding-left: 8px;
}
.sub-menu.open {
    display: block;
}

/* ========== 子功能项样式（浅背景） ========== */
.sub-menu a {
    background-color: #f7f9fc;
    color: #444;
    text-decoration: none;
    padding: 0.4rem 0.8rem;
    display: block;
    border-radius: 4px;
    transition: background 0.2s;
    cursor: pointer;
    font-size: 0.92rem;
}
.sub-menu a:hover {
    background-color: #e8f0fc;
    color: #1f4068;
}

/* 主内容容器 + 过渡动画 */
.main {
    max-width: 1400px;
    margin: 4rem auto;
    padding: 0 2rem 0 240px;
    transition: padding-left 0.3s ease;
}
/* 侧边栏收起时，主内容全屏 */
.main.full-width {
    padding-left: 2rem;
}

.intro {
    text-align: center;
    margin-bottom: 2rem;
}

.intro h2 {
    font-size: 1.8rem;
    color: #1f4068;
    margin-bottom: 0.8rem;
}

.intro p {
    color: #666;
    font-size: 1.05rem;
}

/* 功能列表区域 */
#toolList {
    border-top: 1px solid #dce4ec;
    padding-top: 2.5rem;
}

/* 分类模块 */
.tool-category {
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(31, 64, 104, 0.1);
    padding: 2rem;
    margin-bottom: 2.5rem;
    border: 1px solid #e8edf2;
    scroll-margin-top: 140px;
}

.category-title {
    font-size: 1.4rem;
    color: #1f4068;
    margin-bottom: 1.5rem;
    padding-bottom: 0.8rem;
    border-bottom: 2px solid #e8edf2;
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.category-icon {
    font-size: 1.8rem;
}

/* 工具网格 */
.sub-tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 1.5rem;
}

.sub-tool-card {
    background: #f7f9fc;
    padding: 1.5rem 1rem;
    border-radius: 8px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    border: 1px solid #e8edf2;
}

.sub-tool-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 18px rgba(31, 64, 104, 0.15);
    border-color: #1f4068;
    background: #fff;
}

.sub-tool-card .icon {
    font-size: 2rem;
    margin-bottom: 0.8rem;
    color: #2980b9;
    display: flex;
    justify-content: center;
    align-items: center;
}
.sub-tool-card .icon img {
    width: 100px;
    height: 100px;
    object-fit: contain;
}

.sub-tool-card h4 {
    font-size: 1.05rem;
    margin-bottom: 0.5rem;
    color: #222;
}

.sub-tool-card p {
    color: #777;
    font-size: 0.85rem;
}

/* 底部 */
footer {
    text-align: center;
    padding: 2rem;
    color: #888;
    font-size: 0.9rem;
    background: #fff;
    margin-top: 3rem;
    position: relative;
}

footer .email {
    margin: 0.5rem 0;
}

/* 捐赠悬浮容器 */
.donate-wrap {
    display: inline-block;
    position: relative;
    margin-left: 8px;
    cursor: pointer;
    color: #1f4068;
    font-weight: 500;
}
.donate-tip {
    visibility: hidden;
    opacity: 0;
    position: absolute;
    bottom: 120%;
    left: 50%;
    transform: translateX(-50%);
    background: #fff;
    padding: 12px;
    border-radius: 8px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.2);
    transition: opacity 0.3s, visibility 0.3s;
    z-index: 100;
}
.donate-tip img {
    display: block;
    max-width: 500px;
    height: auto;
}
.donate-wrap:hover .donate-tip {
    visibility: visible;
    opacity: 1;
}

.toggle-side-btn {
    position: fixed;
    left: 5px;   /* 贴最左侧 */
    top: 180px;
    z-index: 100;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: none;
    background: #1f4068;
    color: #fff;
    font-size: 18px;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.toggle-side-btn:hover {
    background: #2a5288;
    transform: scale(1.05);
}

/* 移动端适配 */
@media (max-width: 900px) {
    .side-nav {
        display: none;
    }
    .main {
        padding-left: 2rem;
    }
    .toggle-side-btn {
        display: none;
    }
}

@media (max-width: 768px) {
    .header-wrap {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    .sub-tool-grid {
        grid-template-columns: 1fr 1fr;
    }
    .category-title {
        font-size: 1.2rem;
    }
    .header-wrap > div:last-child {
        display: flex;
        gap: 8px;
        flex-wrap: wrap;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .sub-tool-grid {
        grid-template-columns: 1fr;
    }
}