/* ===== 全局重置与基础 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: "Microsoft YaHei", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #e8ecf1 100%);
    color: #2c3e50;
    line-height: 1.7;
    min-height: 100vh;
    transition: background 0.4s ease, color 0.4s ease;
}

a {
    color: #1a3a5c;
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: #e67e22;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ===== 导航栏 ===== */
.header {
    background: linear-gradient(135deg, #1a3a5c 0%, #2a5a7c 100%);
    color: #fff;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.4rem;
    font-weight: 700;
    color: #fff;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.logo svg {
    width: 40px;
    height: 40px;
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.3));
}

.nav {
    display: flex;
    gap: 20px;
}

.nav a {
    color: #e0e7ef;
    font-size: 0.95rem;
    padding: 6px 0;
    border-bottom: 2px solid transparent;
    transition: all 0.3s ease;
    position: relative;
}

.nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: #e67e22;
    transition: width 0.3s ease;
}

.nav a:hover {
    color: #fff;
}

.nav a:hover::after {
    width: 100%;
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: #fff;
    font-size: 1.6rem;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.menu-toggle:hover {
    transform: scale(1.1);
}

.mobile-menu {
    display: none;
    background: linear-gradient(135deg, #1a3a5c 0%, #2a5a7c 100%);
    padding: 10px 20px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
}

.mobile-menu a {
    display: block;
    color: #e0e7ef;
    padding: 10px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s ease;
}

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

.mobile-menu a:hover {
    color: #e67e22;
    padding-left: 10px;
}

.mobile-menu.open {
    display: block;
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== 搜索框 ===== */
.search-box {
    display: flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 25px;
    overflow: hidden;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

.search-box:focus-within {
    background: rgba(255, 255, 255, 0.25);
    border-color: #e67e22;
    box-shadow: 0 0 15px rgba(230, 126, 34, 0.3);
}

.search-box input {
    border: none;
    padding: 8px 14px;
    outline: none;
    width: 160px;
    font-size: 0.9rem;
    background: transparent;
    color: #fff;
}

.search-box input::placeholder {
    color: rgba(255, 255, 255, 0.6);
}

.search-box button {
    background: linear-gradient(135deg, #e67e22, #d35400);
    border: none;
    color: #fff;
    padding: 8px 16px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    font-weight: 600;
}

.search-box button:hover {
    background: linear-gradient(135deg, #d35400, #e67e22);
    transform: scale(1.05);
}

/* ===== Banner ===== */
.banner {
    position: relative;
    overflow: hidden;
    height: 450px;
    background: linear-gradient(135deg, #1a3a5c 0%, #2a5a7c 50%, #1a3a5c 100%);
}

.banner::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 30% 50%, rgba(230, 126, 34, 0.15) 0%, transparent 50%),
                radial-gradient(circle at 70% 50%, rgba(230, 126, 34, 0.1) 0%, transparent 50%);
    z-index: 1;
}

.banner-slide {
    position: absolute;
    inset: 0;
    opacity: 0;
    transition: opacity 0.8s ease, transform 0.8s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
    padding: 40px;
    z-index: 2;
    transform: scale(0.95);
}

.banner-slide.active {
    opacity: 1;
    transform: scale(1);
}

.banner-slide h2 {
    font-size: 2.4rem;
    margin-bottom: 16px;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    animation: fadeInUp 0.8s ease;
}

.banner-slide p {
    font-size: 1.15rem;
    max-width: 700px;
    margin: 0 auto 20px;
    opacity: 0.9;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.banner-slide .btn {
    background: linear-gradient(135deg, #e67e22, #d35400);
    color: #fff;
    padding: 14px 36px;
    border-radius: 50px;
    font-weight: 600;
    display: inline-block;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(230, 126, 34, 0.4);
    animation: fadeInUp 0.8s ease 0.4s both;
}

.banner-slide .btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 25px rgba(230, 126, 34, 0.6);
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.banner-dots {
    position: absolute;
    bottom: 25px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 12px;
    z-index: 3;
}

.banner-dots span {
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.4);
    cursor: pointer;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.banner-dots span.active {
    background: #e67e22;
    border-color: #fff;
    transform: scale(1.2);
}

.banner-dots span:hover {
    background: rgba(255, 255, 255, 0.7);
}

/* ===== 通用区块 ===== */
.section {
    padding: 70px 0;
    position: relative;
}

.section-title {
    text-align: center;
    font-size: 2rem;
    color: #1a3a5c;
    margin-bottom: 40px;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 70px;
    height: 4px;
    background: linear-gradient(90deg, #e67e22, #f39c12);
    margin: 14px auto 0;
    border-radius: 2px;
}

.section-subtitle {
    text-align: center;
    color: #7f8c8d;
    margin-bottom: 40px;
    font-size: 1.05rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* ===== 网格布局 ===== */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

.grid-3 {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 30px;
}

.grid-4 {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr;
    gap: 20px;
}

/* ===== 卡片 ===== */
.card {
    background: rgba(255, 255, 255, 0.85);
    border-radius: 16px;
    padding: 30px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
    background: rgba(255, 255, 255, 0.95);
}

.card h3 {
    color: #1a3a5c;
    font-size: 1.2rem;
    margin-bottom: 12px;
}

.card p {
    color: #555;
    font-size: 0.95rem;
    line-height: 1.7;
}

/* ===== 关于我们 ===== */
.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: center;
}

.about-text h2 {
    font-size: 1.8rem;
    color: #1a3a5c;
    margin-bottom: 20px;
    position: relative;
    padding-bottom: 10px;
}

.about-text h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background: #e67e22;
}

.about-text p {
    margin-bottom: 16px;
    color: #555;
    line-height: 1.8;
}

.about-stats {
    display: flex;
    gap: 40px;
    margin-top: 25px;
}

.stat-item {
    text-align: center;
    padding: 15px 20px;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 12px;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    transition: all 0.3s ease;
}

.stat-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
}

.stat-item .num {
    font-size: 2.4rem;
    font-weight: 700;
    color: #e67e22;
    line-height: 1.2;
}

.stat-item .label {
    color: #7f8c8d;
    font-size: 0.9rem;
    margin-top: 4px;
}

/* ===== 服务图标 ===== */
.service-icon {
    width: 60px;
    height: 60px;
    margin-bottom: 16px;
    transition: transform 0.3s ease;
}

.card:hover .service-icon {
    transform: rotate(10deg) scale(1.1);
}

/* ===== 解决方案 ===== */
.solution-item {
    background: rgba(255, 255, 255, 0.85);
    border-radius: 16px;
    padding: 28px;
    margin-bottom: 20px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    transition: all 0.3s ease;
}

.solution-item:hover {
    transform: translateX(8px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
    background: rgba(255, 255, 255, 0.95);
}

.solution-item h3 {
    color: #1a3a5c;
    margin-bottom: 8px;
    font-size: 1.15rem;
}

.solution-item p {
    color: #555;
    line-height: 1.7;
}

/* ===== 案例卡片 ===== */
.case-card {
    background: rgba(255, 255, 255, 0.85);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.case-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
}

.case-card .case-body {
    padding: 22px;
}

.case-card h4 {
    color: #1a3a5c;
    margin-bottom: 8px;
    font-size: 1.05rem;
}

.case-card .tag {
    display: inline-block;
    background: linear-gradient(135deg, #e67e22, #d35400);
    color: #fff;
    padding: 3px 14px;
    border-radius: 20px;
    font-size: 0.8rem;
    margin-bottom: 10px;
    font-weight: 600;
}

.case-card p {
    color: #555;
    font-size: 0.95rem;
    line-height: 1.7;
}

/* ===== 评价 ===== */
.testimonial {
    background: rgba(255, 255, 255, 0.85);
    border-radius: 16px;
    padding: 28px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    transition: all 0.3s ease;
}

.testimonial:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
}

.testimonial .stars {
    color: #f1c40f;
    margin-bottom: 10px;
    font-size: 1.2rem;
}

.testimonial p {
    color: #555;
    line-height: 1.7;
    margin-bottom: 12px;
}

.testimonial .author {
    font-weight: 600;
    color: #1a3a5c;
    font-size: 0.95rem;
}

/* ===== 文章 ===== */
.article-item {
    background: rgba(255, 255, 255, 0.85);
    border-radius: 16px;
    padding: 26px;
    margin-bottom: 20px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    transition: all 0.3s ease;
}

.article-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
}

.article-item h3 {
    color: #1a3a5c;
    font-size: 1.1rem;
    margin-bottom: 8px;
}

.article-item h3 a {
    color: #1a3a5c;
    transition: color 0.3s ease;
}

.article-item h3 a:hover {
    color: #e67e22;
}

.article-item .meta {
    color: #95a5a6;
    font-size: 0.85rem;
    margin-bottom: 8px;
}

.article-item .excerpt {
    color: #555;
    margin-bottom: 12px;
    line-height: 1.7;
}

.article-item .read-more {
    color: #e67e22;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-block;
}

.article-item .read-more:hover {
    transform: translateX(5px);
    color: #d35400;
}

/* ===== FAQ ===== */
.faq-item {
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
    padding: 18px 0;
    transition: all 0.3s ease;
}

.faq-item:last-child {
    border-bottom: none;
}

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    font-weight: 600;
    color: #1a3a5c;
    padding: 8px 0;
    transition: color 0.3s ease;
    user-select: none;
}

.faq-question:hover {
    color: #e67e22;
}

.faq-question .icon {
    font-size: 1.4rem;
    transition: transform 0.4s ease;
    color: #e67e22;
    width: 30px;
    text-align: center;
}

.faq-answer {
    display: none;
    padding-top: 12px;
    color: #555;
    line-height: 1.8;
    animation: fadeIn 0.4s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.faq-item.open .faq-answer {
    display: block;
}

.faq-item.open .faq-question .icon {
    transform: rotate(45deg);
}

/* ===== HowTo ===== */
.howto-steps {
    counter-reset: step;
}

.howto-step {
    display: flex;
    gap: 18px;
    margin-bottom: 24px;
    align-items: flex-start;
    padding: 16px;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 12px;
    transition: all 0.3s ease;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

.howto-step:hover {
    background: rgba(255, 255, 255, 0.8);
    transform: translateX(5px);
}

.howto-step .step-num {
    flex-shrink: 0;
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, #1a3a5c, #2a5a7c);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1rem;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15);
}

.howto-step .step-content h4 {
    color: #1a3a5c;
    margin-bottom: 6px;
    font-size: 1.05rem;
}

.howto-step .step-content p {
    color: #555;
    line-height: 1.7;
}

/* ===== 联系我们 ===== */
#contact {
    background: linear-gradient(135deg, #1a3a5c 0%, #2a5a7c 50%, #1a3a5c 100%) !important;
    position: relative;
}

#contact::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 20% 30%, rgba(230, 126, 34, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 80% 70%, rgba(230, 126, 34, 0.08) 0%, transparent 50%);
}

.contact-info {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 25px;
    position: relative;
    z-index: 1;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 18px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s ease;
}

.contact-item:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-3px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.2);
}

.contact-item svg {
    width: 36px;
    height: 36px;
    flex-shrink: 0;
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.2));
}

.contact-item div {
    color: #e0e7ef;
    font-size: 0.95rem;
    line-height: 1.6;
}

.contact-item strong {
    color: #fff;
    font-size: 1rem;
}

/* ===== 页脚 ===== */
.footer {
    background: linear-gradient(135deg, #1a3a5c 0%, #0f3460 100%);
    color: #e0e7ef;
    padding: 50px 0 20px;
    position: relative;
}

.footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, #e67e22, #f39c12, #e67e22);
}

.footer .container {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 35px;
}

.footer h4 {
    color: #fff;
    margin-bottom: 18px;
    font-size: 1.1rem;
    position: relative;
    padding-bottom: 8px;
}

.footer h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 30px;
    height: 2px;
    background: #e67e22;
}

.footer a {
    color: #b0c4de;
    display: block;
    margin-bottom: 10px;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.footer a:hover {
    color: #e67e22;
    padding-left: 5px;
}

.footer p {
    color: #b0c4de;
    font-size: 0.9rem;
    line-height: 1.7;
}

.footer-bottom {
    text-align: center;
    padding-top: 25px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: 25px;
    font-size: 0.9rem;
}

.footer-bottom p {
    margin-bottom: 5px;
}

/* ===== 返回顶部 ===== */
.back-top {
    position: fixed;
    bottom: 40px;
    right: 40px;
    background: linear-gradient(135deg, #1a3a5c, #2a5a7c);
    color: #fff;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 999;
    border: none;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
    font-size: 1.3rem;
}

.back-top.show {
    opacity: 1;
    visibility: visible;
}

.back-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 25px rgba(0, 0, 0, 0.4);
    background: linear-gradient(135deg, #2a5a7c, #1a3a5c);
}

/* ===== 暗黑模式切换 ===== */
.dark-mode-toggle {
    position: fixed;
    bottom: 100px;
    right: 40px;
    background: linear-gradient(135deg, #1a3a5c, #2a5a7c);
    color: #fff;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 999;
    border: none;
    font-size: 1.3rem;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
    transition: all 0.3s ease;
}

.dark-mode-toggle:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 25px rgba(0, 0, 0, 0.4);
}

/* ===== 暗黑模式 ===== */
body.dark {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    color: #e0e7ef;
}

body.dark .card {
    background: rgba(22, 33, 62, 0.85);
    border-color: rgba(255, 255, 255, 0.05);
    color: #e0e7ef;
}

body.dark .card p {
    color: #b0c4de;
}

body.dark .card h3 {
    color: #e0e7ef;
}

body.dark .solution-item {
    background: rgba(22, 33, 62, 0.85);
    border-color: rgba(255, 255, 255, 0.05);
}

body.dark .solution-item p {
    color: #b0c4de;
}

body.dark .solution-item h3 {
    color: #e0e7ef;
}

body.dark .testimonial {
    background: rgba(22, 33, 62, 0.85);
    border-color: rgba(255, 255, 255, 0.05);
}

body.dark .testimonial p {
    color: #b0c4de;
}

body.dark .testimonial .author {
    color: #e0e7ef;
}

body.dark .article-item {
    background: rgba(22, 33, 62, 0.85);
    border-color: rgba(255, 255, 255, 0.05);
}

body.dark .article-item p {
    color: #b0c4de;
}

body.dark .article-item h3 a {
    color: #e0e7ef;
}

body.dark .faq-item {
    border-bottom-color: rgba(255, 255, 255, 0.1);
}

body.dark .faq-question {
    color: #e0e7ef;
}

body.dark .faq-answer {
    color: #b0c4de;
}

body.dark .section-title {
    color: #e0e7ef;
}

body.dark .section-subtitle {
    color: #b0c4de;
}

body.dark .header {
    background: linear-gradient(135deg, #0f3460, #1a3a5c);
}

body.dark .banner {
    background: linear-gradient(135deg, #0f3460, #1a3a5c, #0f3460);
}

body.dark .footer {
    background: linear-gradient(135deg, #0f3460, #1a1a2e);
}

body.dark .back-top {
    background: linear-gradient(135deg, #0f3460, #1a3a5c);
}

body.dark .dark-mode-toggle {
    background: linear-gradient(135deg, #0f3460, #1a3a5c);
}

body.dark .about-text p {
    color: #b0c4de;
}

body.dark .stat-item {
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.1);
}

body.dark .stat-item .label {
    color: #b0c4de;
}

body.dark .case-card {
    background: rgba(22, 33, 62, 0.85);
    border-color: rgba(255, 255, 255, 0.05);
}

body.dark .case-card p {
    color: #b0c4de;
}

body.dark .case-card h4 {
    color: #e0e7ef;
}

body.dark .howto-step {
    background: rgba(255, 255, 255, 0.05);
}

body.dark .howto-step p {
    color: #b0c4de;
}

body.dark .howto-step h4 {
    color: #e0e7ef;
}

body.dark .contact-item {
    background: rgba(255, 255, 255, 0.05);
}

/* ===== 滚动动画 ===== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.7s ease, transform 0.7s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== 数字动画 ===== */
.count-up {
    display: inline-block;
}

/* ===== 响应式 ===== */
@media (max-width: 992px) {
    .grid-4 {
        grid-template-columns: 1fr 1fr;
    }
    
    .footer .container {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    .nav {
        display: none;
    }
    
    .menu-toggle {
        display: block;
    }
    
    .mobile-menu.open {
        display: block;
    }
    
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .contact-info {
        grid-template-columns: 1fr;
    }
    
    .footer .container {
        grid-template-columns: 1fr;
    }
    
    .banner {
        height: 320px;
    }
    
    .banner-slide h2 {
        font-size: 1.6rem;
    }
    
    .banner-slide p {
        font-size: 0.95rem;
    }
    
    .search-box input {
        width: 100px;
    }
    
    .back-top {
        bottom: 20px;
        right: 20px;
        width: 44px;
        height: 44px;
        font-size: 1.1rem;
    }
    
    .dark-mode-toggle {
        bottom: 70px;
        right: 20px;
        width: 44px;
        height: 44px;
        font-size: 1.1rem;
    }
    
    .section {
        padding: 50px 0;
    }
    
    .section-title {
        font-size: 1.6rem;
    }
    
    .about-stats {
        flex-direction: column;
        gap: 15px;
    }
    
    .howto-step {
        flex-direction: column;
    }
    
    .contact-item {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .banner {
        height: 280px;
    }
    
    .banner-slide h2 {
        font-size: 1.3rem;
    }
    
    .banner-slide p {
        font-size: 0.85rem;
    }
    
    .banner-slide .btn {
        padding: 10px 24px;
        font-size: 0.9rem;
    }
    
    .card {
        padding: 20px;
    }
    
    .container {
        padding: 0 15px;
    }
}

/* ===== 辅助 ===== */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}