/* 公共样式 */

/* 容器 */
.container {
}

/* 导航栏容器 - 全宽无左右边距 */
.nav-container {
    width: 100%;
    margin: 0 auto;
    padding:0 88px 0 61px;
}

/* 主导航 - 固定定位 */
.main-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0);
    height: 80px;
    box-shadow: none;
    transition: background 0.3s ease, box-shadow 0.3s ease;
}

/* 默认深色文字样式（用于非首页页面） */
.main-nav.dark-text .nav-menu li a {
    color: #333D47;
}

.main-nav.dark-text .nav-menu li a:hover,
.main-nav.dark-text .nav-menu li a.active {
    color: #0073ff;
}

.main-nav.dark-text .search-btn-nav {
    background-image: url('../images/search-dark.png');
}

.main-nav.dark-text .logo img {
    content: url('../images/logo-dark.png');
}

/* 滚动后的导航栏样式 - 仅用于首页 */
.main-nav.scrolled {
    background: rgba(255, 255, 255, 0);
    box-shadow: none;
}

.main-nav.scrolled .nav-menu li a {
    color: #333D47;
}

.main-nav.scrolled .nav-menu li a:hover,
.main-nav.scrolled .nav-menu li a.active {
    color: #0073ff;
}

.main-nav.scrolled .search-btn-nav {
    background-image: url('../images/search-dark.png');
}

.main-nav.scrolled .logo img {
    content: url('../images/logo-dark.png');
}

/* ==================== 非首页页面导航栏滚动后样式 ==================== */
/* 非首页页面（如 about.html）导航栏默认就是深色文字，滚动后需要白色背景 */
body:not(.home-page) .main-nav.scrolled,
body.about-page .main-nav.scrolled,
body.news-page .main-nav.scrolled,
body.faculty-page .main-nav.scrolled {
    background: #fff !important;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.main-nav .nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    flex-shrink: 0;
}

.logo img {
    width: 549px;
    height: 54px;
    margin-right: 10px;
}

.institute-name {
    font-size: 18px;
    font-weight: bold;
    color: #fff;
    text-shadow: 0 1px 3px rgba(0,0,0,0.3);
    white-space: nowrap;
}

.nav-menu {
    display: flex;
    gap: 0;
    margin-left: auto;
}

.nav-menu li {
    position: relative;
}

.nav-menu li a {
    display: block;
    padding: 0 16px;
    height: 70px;
    line-height: 70px;
    color: rgba(255,255,255,0.9);
    font-size: 18px;
    font-weight: 400;
    transition: all 0.3s;
    white-space: nowrap;
}

.nav-menu li a:hover,
.nav-menu li a.active {
    color: #0073ff;
}

/* ========== 二级菜单 ========== */
.nav-menu li.has-submenu {
    position: relative;
}

.nav-menu li.has-submenu .sub-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    background: #fff;
    border-radius: 4px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.12);
    padding: 8px 0;
    min-width: 140px;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 1001;
}

.nav-menu li.has-submenu .sub-menu::before {
    content: '';
    position: absolute;
    top: -6px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 0;
    border-left: 6px solid transparent;
    border-right: 6px solid transparent;
    border-bottom: 6px solid #fff;
}

.nav-menu li.has-submenu:hover .sub-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.nav-menu li.has-submenu .sub-menu li {
    display: block;
    width: 100%;
}

.nav-menu li.has-submenu .sub-menu li a {
    display: block;
    padding: 0 20px;
    height: 40px;
    line-height: 40px;
    font-size: 14px;
    color: #333D47;
    white-space: nowrap;
    transition: all 0.2s ease;
}

.nav-menu li.has-submenu .sub-menu li a:hover {
    color: #0073ff;
    background: #f5f9ff;
}

/* 汉堡菜单按钮 - 默认隐藏 */
.hamburger-btn {
    display: none;
}

/* 导航栏搜索按钮 */
.search-btn-nav {
    width: 26px;
    height: 26px;
    background: transparent url('../images/search.png') center center no-repeat;
    background-size: 26px 26px;
    border: none;
    cursor: pointer;
    margin-left: 15px;
    transition: opacity 0.3s;
}

.search-btn-nav:hover {
    opacity: 0.8;
}

/* 右侧悬浮导航 */
.side-nav {
    position: fixed;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 999;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.side-dot {
    display: block;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: rgba(0, 91, 172, 0.3);
    border: 2px solid transparent;
    transition: all 0.3s;
    cursor: pointer;
}

.side-dot:hover,
.side-dot.active {
    background: #0073ff;
    border-color: #fff;
    box-shadow: 0 0 0 2px #0073ff;
}

/* 更多按钮 */
.more-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 97px;
    height: 31px;
    background: linear-gradient(270deg, #8F3DF3 0%, #0073FF 100%);
    color: #fff;
    border-radius: 4px;
    font-size: 14px;
    transition: opacity 0.3s;
}

.more-btn::after {
    content: '';
    display: inline-block;
    width: 23.69px;
    height: 6.76px;
    background: url('../images/right.png') center center no-repeat;
    background-size: contain;
    margin-left: 6px;
}

.more-btn:hover {
    opacity: 0.9;
}

/* 详情按钮 */
.detail-btn {
    display: inline-block;
    padding: 10px 30px;
    border: 1px solid #0073ff;
    color: #0073ff;
    border-radius: 4px;
    font-size: 14px;
    transition: all 0.3s;
    margin-top: 20px;
}

.detail-btn:hover {
    background: #0073ff;
    color: #fff;
}

/* 区块标题 */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    margin-top: -60px;
}

.section-header h2 {
    font-size: 32px;
    font-weight: 400;
    color: #333;
    position: relative;
    padding-left: 0;
}

.section-header h2 span {
    color: #0073ff;
}

/* 搜索弹窗 */
.search-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 10000;
    display: none;
    align-items: center;
    justify-content: center;
}

.search-modal.active {
    display: flex;
}

.search-modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.6);
}

.search-modal-content {
    position: relative;
    z-index: 1;
    width: 100%;
    max-width: 600px;
    padding: 0 20px;
}

.search-modal-close {
    position: fixed;
    top: 30px;
    right: 40px;
    width: 40px;
    height: 40px;
    background: transparent;
    border: none;
    color: #fff;
    font-size: 40px;
    cursor: pointer;
    line-height: 1;
    opacity: 0.8;
    transition: opacity 0.3s;
    z-index: 10001;
}

.search-modal-close:hover {
    opacity: 1;
}

.search-modal-form {
    display: flex;
    align-items: center;
    background: #fff;
    border-radius: 8px;
    padding: 8px 20px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.15);
}

.search-modal-form input {
    flex: 1;
    height: 44px;
    padding: 0;
    border: none;
    background: transparent;
    font-size: 16px;
    outline: none;
}

.search-modal-form input::placeholder {
    color: #999;
}

.search-modal-btn {
    width: auto;
    height: auto;
    max-width: 24px;
    max-height: 24px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 10px;
    flex-shrink: 0;
}

/* 响应式 */
@media (max-width: 1600px) {
    .screen-news .screen-content,
    .screen-intro .screen-content,
    .screen-subjects .screen-content,
    .footer-content {
        padding-left: 150px;
        padding-right: 150px;
    }
}

@media (max-width: 1200px) {
    .screen-news .screen-content,
    .screen-intro .screen-content,
    .screen-subjects .screen-content,
    .footer-content {
        padding-left: 50px;
        padding-right: 50px;
    }
}

@media (max-width: 1200px) {
    .container {
        width: 100%;
    }
}

@media (max-width: 1700px) {
    .nav-menu li a {
        padding: 0 14px;
        font-size: 16px;
    }

    .logo img {
        width: 480px;
        height: auto;
    }
}

@media (max-width: 1600px) {
    .nav-menu li a {
        padding: 0 12px;
        font-size: 15px;
    }

    .logo img {
        width: 420px;
        height: auto;
    }
}

@media (max-width: 1400px) {
    .nav-menu li a {
        padding: 0 10px;
        font-size: 14px;
    }

    .logo img {
        width: 380px;
        height: auto;
    }
}

@media (max-width: 1280px) {
    .nav-menu li a {
        padding: 0 6px;
        font-size: 13px;
    }

    .logo img {
        width: 320px;
        height: auto;
    }
}

/* ==================== 1200px 以下：切换为汉堡菜单 ==================== */
@media (max-width: 1200px) {
    .main-nav {
        height: 60px;
    }

    .nav-container {
        padding: 0 15px;
    }

    .logo img {
        width: 240px;
        height: auto;
    }

    .nav-menu {
        display: none;
        position: absolute;
        top: 60px;
        left: 0;
        right: 0;
        background: #fff;
        flex-direction: column;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
        padding: 10px 0;
        z-index: 999;
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-menu li {
        width: 100%;
    }

    .nav-menu li a {
        display: block;
        padding: 0 20px;
        height: 48px;
        line-height: 48px;
        font-size: 15px;
        color: #333D47;
        border-bottom: 1px solid #f0f0f0;
    }

    .nav-menu li a.active {
        color: #0073ff;
        background: #f5f9ff;
    }

    .nav-menu li:last-child a {
        border-bottom: none;
    }

    /* 移动端二级菜单样式 */
    .nav-menu li.has-submenu .sub-menu {
        position: static;
        transform: none;
        opacity: 1;
        visibility: visible;
        display: none;
        box-shadow: none;
        border-radius: 0;
        padding: 0;
        background: #f8f9fa;
        min-width: auto;
    }

    .nav-menu li.has-submenu.active .sub-menu {
        display: block;
    }

    .nav-menu li.has-submenu .sub-menu li a {
        height: 42px;
        line-height: 42px;
        font-size: 14px;
        padding-left: 40px;
        color: #555;
        border-bottom: 1px solid #eee;
    }

    .nav-menu li.has-submenu .sub-menu li:last-child a {
        border-bottom: none;
    }

    .search-btn-nav {
        margin-left: auto;
    }

    .hamburger-btn {
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        width: 32px;
        height: 32px;
        background: transparent;
        border: none;
        cursor: pointer;
        margin-left: 12px;
        padding: 0;
        gap: 5px;
    }

    .hamburger-btn span {
        display: block;
        width: 22px;
        height: 2px;
        background: #0073ff;
        border-radius: 2px;
        transition: all 0.3s ease;
        transform-origin: center;
    }

    .hamburger-btn.active span:nth-child(1) {
        transform: translateY(7px) rotate(45deg);
    }

    .hamburger-btn.active span:nth-child(2) {
        opacity: 0;
    }

    .hamburger-btn.active span:nth-child(3) {
        transform: translateY(-7px) rotate(-45deg);
    }
}

/* ==================== PC端导航菜单公共样式 ==================== */
/* PC端展开按钮 - 默认隐藏 */
.pc-nav-toggle {
    display: none;
}

/* 1200px以上显示PC端展开按钮，隐藏移动端汉堡按钮 */
@media (min-width: 1201px) {
    .pc-nav-toggle {
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        width: 32px;
        height: 32px;
        background: transparent;
        border: none;
        cursor: pointer;
        margin-left: 12px;
        padding: 0;
        gap: 5px;
    }

    .pc-nav-toggle span {
        display: block;
        width: 22px;
        height: 2px;
        background: #333D47;
        border-radius: 2px;
        transition: all 0.3s ease;
        transform-origin: center;
    }

    /* 首页展开按钮为白色 */
    .home-page .pc-nav-toggle span {
        background: #fff;
    }

    /* 导航栏滚动后或菜单打开时，展开按钮变为深色 */
    .main-nav.scrolled .pc-nav-toggle span,
    body.pc-nav-open .pc-nav-toggle span {
        background: #333D47;
    }

    body.pc-nav-open .pc-nav-toggle span:nth-child(1) {
        transform: translateY(7px) rotate(45deg);
    }

    body.pc-nav-open .pc-nav-toggle span:nth-child(2) {
        opacity: 0;
    }

    body.pc-nav-open .pc-nav-toggle span:nth-child(3) {
        transform: translateY(-7px) rotate(-45deg);
    }

    /* PC端隐藏移动端汉堡按钮 */
    .hamburger-btn {
        display: none !important;
    }
}

/* 1200px以下隐藏PC端展开按钮 */
@media (max-width: 1200px) {
    .pc-nav-toggle {
        display: none !important;
    }
}

/* PC端导航菜单覆盖层 */
.pc-nav-overlay {
    position: fixed;
    top: 80px;
    left: 0;
    right: 0;
    bottom: 0;
    background: #fff;
    z-index: 999;
    visibility: hidden;
    transform: scaleY(0);
    transform-origin: top;
    transition: transform 0.4s ease 0.2s, visibility 0s ease 0.6s;
    overflow-y: auto;
}

.pc-nav-overlay.active {
    visibility: visible;
    transform: scaleY(1);
    transition: transform 0.4s ease 0.2s, visibility 0s ease 0s;
}

.pc-nav-panel {
    width: 100%;
    min-height: 100%;
    position: relative;
    padding: 60px 88px 60px 61px;
    box-sizing: border-box;
}

.pc-nav-close {
    display: none;
}

.pc-nav-content {
    max-width: 1400px;
    margin: 0 auto;
}

.pc-nav-columns {
    display: flex;
    flex-wrap: nowrap;
    justify-content: space-between;
    gap: 20px;
}

.pc-nav-column {
    flex: 0 0 auto;
    min-width: 0;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}

/* 菜单打开时各列依次淡入 */
.pc-nav-overlay.active .pc-nav-column:nth-child(1) { opacity: 1; transform: translateY(0); transition-delay: 0.7s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(2) { opacity: 1; transform: translateY(0); transition-delay: 0.78s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(3) { opacity: 1; transform: translateY(0); transition-delay: 0.86s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(4) { opacity: 1; transform: translateY(0); transition-delay: 0.94s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(5) { opacity: 1; transform: translateY(0); transition-delay: 1.02s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(6) { opacity: 1; transform: translateY(0); transition-delay: 1.10s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(7) { opacity: 1; transform: translateY(0); transition-delay: 1.18s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(8) { opacity: 1; transform: translateY(0); transition-delay: 1.26s; }
.pc-nav-overlay.active .pc-nav-column:nth-child(9) { opacity: 1; transform: translateY(0); transition-delay: 1.34s; }

.pc-nav-title {
    font-family: 'Microsoft YaHei UI', sans-serif;
    font-weight: 500;
    font-size: 20px;
    color: #333;
    text-decoration: none;
    display: block;
    margin-bottom: 12px;
    padding-bottom: 8px;
    position: relative;
    transition: color 0.3s ease;
}

.pc-nav-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 24px;
    height: 2px;
    background: #0073ff;
}

.pc-nav-title:hover,
.pc-nav-title.active {
    color: #0073ff;
}

.pc-nav-links {
    list-style: none;
    padding: 0;
    margin: 0 0 16px 0;
}

.pc-nav-links li {
    margin-bottom: 8px;
}

.pc-nav-links li a {
    font-family: 'Microsoft YaHei UI', sans-serif;
    font-weight: 400;
    font-size: 16px;
    color: #666;
    text-decoration: none;
    transition: color 0.3s ease;
    display: block;
}

.pc-nav-links li a:hover {
    color: #0073ff;
}

/* PC端导航打开时，顶部导航栏变为白色背景 */
body.pc-nav-open .main-nav {
    background: #fff !important;
}

body.pc-nav-open .main-nav .nav-menu li a {
    color: #333D47;
}

body.pc-nav-open .main-nav .search-btn-nav {
    background-image: url('../images/search-dark.png');
}

body.pc-nav-open .main-nav .logo img {
    content: url('../images/logo-dark.png');
}

/* 1200px以下隐藏PC端导航覆盖层 */
@media (max-width: 1200px) {
    .pc-nav-overlay {
        display: none !important;
    }
}

/* ==================== 底部栏公共样式 ==================== */
.page-footer,
.subjects-footer {
    background: url('../images/bottom-bg.png') center center no-repeat;
    background-size: cover;
    color: #fff;
    width: 100%;
    min-height: 245px;
    display: flex;
    flex-direction: column;
    padding: 0 300px;
}

/* 首页学科布局内的底部栏特殊处理 */
.subjects-footer {
    margin-top: auto;
}

/* 第一排 */
.footer-row-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 30px 0;
}

.page-footer .footer-links,
.subjects-footer .footer-links {
    display: flex;
    gap: 40px;
}

.page-footer .footer-links a,
.subjects-footer .footer-links a {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: #fff;
    text-decoration: none;
}

.page-footer .footer-links a span,
.subjects-footer .footer-links a span {
    font-family: 'Microsoft YaHei UI', sans-serif;
    font-weight: 400;
    font-size: 14px;
}

.page-footer .footer-links a::before,
.subjects-footer .footer-links a::before {
    content: '';
    width: 32px;
    height: 32px;
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
    transition: background-image 0.3s;
}

/* 图标默认 */
.footer-links a[data-icon="1"]::before { background-image: url('../images/icon (1).png'); }
.footer-links a[data-icon="2"]::before { background-image: url('../images/icon (2).png'); }
.footer-links a[data-icon="3"]::before { background-image: url('../images/icon (3).png'); }
.footer-links a[data-icon="4"]::before { background-image: url('../images/icon (4).png'); }
.footer-links a[data-icon="5"]::before { background-image: url('../images/icon (5).png'); }
.footer-links a[data-icon="6"]::before { background-image: url('../images/icon (6).png'); }
.footer-links a[data-icon="7"]::before { background-image: url('../images/icon (7).png'); }
.footer-links a[data-icon="8"]::before { background-image: url('../images/icon (8).png'); }

/* 图标悬停 */
.footer-links a[data-icon="1"]:hover::before { background-image: url('../images/icon_a (1).png'); }
.footer-links a[data-icon="2"]:hover::before { background-image: url('../images/icon_a (2).png'); }
.footer-links a[data-icon="3"]:hover::before { background-image: url('../images/icon_a (3).png'); }
.footer-links a[data-icon="4"]:hover::before { background-image: url('../images/icon_a (4).png'); }
.footer-links a[data-icon="5"]:hover::before { background-image: url('../images/icon_a (5).png'); }
.footer-links a[data-icon="6"]:hover::before { background-image: url('../images/icon_a (6).png'); }
.footer-links a[data-icon="7"]:hover::before { background-image: url('../images/icon_a (7).png'); }
.footer-links a[data-icon="8"]:hover::before { background-image: url('../images/icon_a (8).png'); }

.footer-contact {
    font-family: 'Microsoft YaHei UI', sans-serif;
    font-weight: 400;
    font-size: 12px;
    line-height: 1.8;
    text-align: left;
}

.footer-contact p {
    margin: 0;
}

/* 第二排 */
.footer-row-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-right: 150px;
}

.page-footer .footer-logo img,
.subjects-footer .footer-logo img {
    width: 507px;
    height: 53px;
}

.page-footer .footer-qr,
.subjects-footer .footer-qr {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    margin-right: 20px;
}

.page-footer .footer-qr img,
.subjects-footer .footer-qr img {
    width: 80px;
    height: 80px;
}

.page-footer .footer-qr span,
.subjects-footer .footer-qr span {
    font-family: 'Microsoft YaHei UI', sans-serif;
    font-weight: 400;
    font-size: 12px;
    color: #fff;
}

/* ==================== 底部栏响应式 ==================== */
@media (max-width: 1920px) {
    .page-footer,
    .subjects-footer {
        padding: 0 300px;
    }

    .footer-row-bottom {
        padding-right: 150px;
    }

    .page-footer .footer-qr,
    .subjects-footer .footer-qr {
        margin-right: 20px;
    }
}

@media (max-width: 1600px) {
    .page-footer,
    .subjects-footer {
        padding: 0 120px;
        height: auto;
        min-height: 245px;
    }

    .footer-row-top {
        padding: 25px 0;
    }

    .page-footer .footer-links,
    .subjects-footer .footer-links {
        gap: 30px;
    }

    .footer-row-bottom {
        padding-right: 60px;
    }

    .page-footer .footer-logo img,
    .subjects-footer .footer-logo img {
        width: 420px;
        height: auto;
    }

    .page-footer .footer-qr,
    .subjects-footer .footer-qr {
        margin-right: 100px;
    }
}

@media (max-width: 1440px) {
    .page-footer,
    .subjects-footer {
        padding: 0 80px;
    }

    .page-footer .footer-links,
    .subjects-footer .footer-links {
        gap: 25px;
    }

    .page-footer .footer-links a span,
    .subjects-footer .footer-links a span {
        font-size: 13px;
    }

    .footer-row-bottom {
        padding-right: 40px;
    }

    .page-footer .footer-qr,
    .subjects-footer .footer-qr {
        margin-right: 120px;
    }

    .page-footer .footer-logo img,
    .subjects-footer .footer-logo img {
        width: 380px;
    }
}

@media (max-width: 1366px) {
    .page-footer,
    .subjects-footer {
        padding: 0 60px;
    }

    .footer-row-top {
        padding: 20px 0;
    }

    .page-footer .footer-links,
    .subjects-footer .footer-links {
        gap: 20px;
    }

    .page-footer .footer-links a::before,
    .subjects-footer .footer-links a::before {
        width: 28px;
        height: 28px;
    }

    .page-footer .footer-links a span,
    .subjects-footer .footer-links a span {
        font-size: 12px;
    }

    .footer-contact {
        font-size: 11px;
    }

    .footer-row-bottom {
        padding-right: 30px;
    }

    .page-footer .footer-logo img,
    .subjects-footer .footer-logo img {
        width: 340px;
    }

    .page-footer .footer-qr img,
    .subjects-footer .footer-qr img {
        width: 70px;
        height: 70px;
    }

    .page-footer .footer-qr,
    .subjects-footer .footer-qr {
        margin-right: 120px;
    }
}

@media (max-width: 1280px) {
    .page-footer,
    .subjects-footer {
        padding: 0 40px;
    }

    .page-footer .footer-links,
    .subjects-footer .footer-links {
        gap: 15px;
    }

    .page-footer .footer-logo img,
    .subjects-footer .footer-logo img {
        width: 300px;
    }

    .page-footer .footer-qr,
    .subjects-footer .footer-qr {
        margin-right: 120px;
    }
}

@media (max-width: 1024px) {
    .page-footer,
    .subjects-footer {
        padding: 0 20px;
        height: auto;
    }

    .footer-row-top {
        flex-direction: column;
        gap: 15px;
        padding: 20px 0;
    }

    .page-footer .footer-links,
    .subjects-footer .footer-links {
        display: grid;
        grid-template-columns: repeat(4, 1fr);
        gap: 15px 10px;
        width: 100%;
    }

    .page-footer .footer-links a,
    .subjects-footer .footer-links a {
        gap: 6px;
    }

    .footer-contact {
        text-align: center;
    }

    .page-footer .footer-qr,
    .subjects-footer .footer-qr {
        margin-right: 0px;
    }

    .footer-row-bottom {
        padding: 15px 0;
    }

    .page-footer .footer-logo img,
    .subjects-footer .footer-logo img {
        width: 280px;
    }
}

@media (max-width: 768px) {
    .page-footer {
        padding: 0 15px;
    }

    .footer-row-top {
        flex-direction: column;
        padding: 20px 0;
        gap: 20px;
    }

    .page-footer .footer-links,
    .subjects-footer .footer-links {
        display: grid;
        grid-template-columns: repeat(4, 1fr);
        gap: 20px 10px;
        width: 100%;
    }

    .page-footer .footer-links a,
    .subjects-footer .footer-links a {
        flex-direction: column;
        align-items: center;
        gap: 8px;
    }

    .page-footer .footer-links a span,
    .subjects-footer .footer-links a span {
        font-size: 12px;
    }

    .page-footer .footer-links a::before,
    .subjects-footer .footer-links a::before {
        width: 50px;
        height: 50px;
    }

    /* 移动端 footer 使用 icon-b 系列图标 */
    .page-footer .footer-links a[data-icon="1"]::before,
    .subjects-footer .footer-links a[data-icon="1"]::before { background-image: url('../images/icon-b (1).png'); }
    .page-footer .footer-links a[data-icon="2"]::before,
    .subjects-footer .footer-links a[data-icon="2"]::before { background-image: url('../images/icon-b (2).png'); }
    .page-footer .footer-links a[data-icon="3"]::before,
    .subjects-footer .footer-links a[data-icon="3"]::before { background-image: url('../images/icon-b (3).png'); }
    .page-footer .footer-links a[data-icon="4"]::before,
    .subjects-footer .footer-links a[data-icon="4"]::before { background-image: url('../images/icon-b (4).png'); }
    .page-footer .footer-links a[data-icon="5"]::before,
    .subjects-footer .footer-links a[data-icon="5"]::before { background-image: url('../images/icon-b (5).png'); }
    .page-footer .footer-links a[data-icon="6"]::before,
    .subjects-footer .footer-links a[data-icon="6"]::before { background-image: url('../images/icon-b (6).png'); }
    .page-footer .footer-links a[data-icon="7"]::before,
    .subjects-footer .footer-links a[data-icon="7"]::before { background-image: url('../images/icon-b (7).png'); }
    .page-footer .footer-links a[data-icon="8"]::before,
    .subjects-footer .footer-links a[data-icon="8"]::before { background-image: url('../images/icon-b (8).png'); }

    .footer-contact {
        text-align: center;
        font-size: 12px;
        padding: 0 15px;
    }

    .footer-contact p {
        margin: 4px 0;
        line-height: 1.6;
    }

    /* 移动端：将第一排拆分为两排 */
    .footer-contact p:first-child {
        font-size: 0;
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 4px;
    }

    .footer-contact p:first-child::before {
        content: '研究院办公地点：国家超级计算长沙中心壹号楼';
        display: block;
        font-size: 12px;
    }

    .footer-contact p:first-child::after {
        content: '办公电话：88822024';
        display: block;
        font-size: 12px;
    }

    .footer-row-bottom {
        flex-direction: column;
        padding: 15px 0;
        gap: 15px;
    }

    .page-footer .footer-logo,
    .subjects-footer .footer-logo {
        display: none;
    }

    .page-footer .footer-qr img,
    .subjects-footer .footer-qr img {
        width: 80px;
        height: 80px;
        margin-top: -25px;
    }

    .page-footer .footer-qr span,
    .subjects-footer .footer-qr span {
        display: none;
    }
}

/* ========== 回到顶部按钮 ========== */
.back-to-top {
    position: fixed;
    right: 30px;
    bottom: 30px;
    width: 48px;
    height: 48px;
    background: #fff;
    border: 1px solid #ddd;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: #0073ff;
    border-color: #0073ff;
}

.back-to-top::before {
    content: '';
    width: 12px;
    height: 12px;
    border-top: 2px solid #666;
    border-right: 2px solid #666;
    transform: rotate(-45deg);
    margin-top: 4px;
    transition: border-color 0.3s ease;
}

.back-to-top:hover::before {
    border-top-color: #fff;
    border-right-color: #fff;
}

/* 移动端回到顶部按钮 */
@media (max-width: 768px) {
    .back-to-top {
        right: 15px;
        bottom: 15px;
        width: 40px;
        height: 40px;
    }

    .back-to-top::before {
        width: 10px;
        height: 10px;
    }
}