:root {
    --primary-color: #2A3950;
    --accent-color: #FF6B6B;
    --text-color: #333;
    --bg-light: #f9f9f9;
    --transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Helvetica Neue', Arial, sans-serif;
}

.logo {
    animation: fadeInUp 1s ease;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

body {
    background-color: var(--bg-light);
    line-height: 1.6;
}

/* 头部样式 */
.hero-header {
    color: white;
    padding: 4rem 0 2rem;
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    width: 100%;
}

.branding {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    margin-bottom: 4rem;
    position: relative;
}

.logo {
    width: 500px;
    margin-bottom: 8rem;
    transition: var(--transition);
    filter: drop-shadow(0 2px 4px rgba(0,0,0,0.2));
}

.logo:hover {
    transform: rotate(-5deg) scale(1.1);
}

.site-title {
    font-size: 4rem;
    letter-spacing: 1.5px;
    line-height: 1.2;
    margin-bottom: 2rem;
}

.site-subtitle {
    font-size: 2rem;
    opacity: 0.9;
    font-weight: 300;
}

/* 导航菜单 */
.nav-container {
    margin-top: 12rem;
}

.main-nav {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

.nav-item {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    padding: 2rem 1.5rem;
    min-height: 180px;
    width: 100%;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
}

/* 图标和文字放大 */
.nav-item i {
    font-size: 3rem;  /* 原约1.5rem */
    margin-bottom: 1rem;
}

.nav-item:hover {
    background: var(--accent-color);
    transform: translateY(-5px);
}

.nav-item a {
    font-size: 1.5rem;
    color: white;
    text-decoration: none;
    font-weight: 500;
    display: block;
}

/* 调整网格布局 */
.main-nav {
    grid-template-columns: repeat(4, minmax(220px, 1fr));
    gap: 2rem;
}

/* 响应式调整 */
@media (max-width: 1200px) {
    .main-nav {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 992px) {
    .main-nav {
        grid-template-columns: repeat(2, 1fr);
    }

    .nav-item {
        min-height: 160px;
    }
}

@media (max-width: 576px) {
    .main-nav {
        grid-template-columns: 1fr;
    }

    .nav-item {
        min-height: 120px;
        padding: 1.5rem;
    }
}

/* 主要内容区 */
.main-content {
    max-width: 1200px;
    margin: 4rem auto;
    padding: 0 2rem;
}

.intro-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
    margin-bottom: 4rem;
}

.intro-text {
    background: white;
    padding: 2rem;
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.intro-text h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-size: 2rem;
}

.intro {
    font-size: 16px;
    line-height: 1.5;
    color: #595959;
    margin-bottom: 30px;
}


.video-container {
    position: relative;
    padding-top: 15%;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

/* 响应式设计 */
@media (max-width: 992px) {
    .main-nav {
        grid-template-columns: repeat(2, 1fr);
    }

    .intro-section {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .branding {
        flex-direction: column;
        text-align: center;
    }

    .logo {
        margin: 0 0 1rem 0;
    }

    .main-nav {
        grid-template-columns: 1fr;
    }

    .nav-item {
        padding: 1rem;
    }
}

/* 视频容器样式 */
.video-container {
    position: relative;
    width: 100%;
    max-width: 854px;  /* 匹配视频原始宽度 */
    margin: 0 auto;    /* 居中显示 */
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 8px 30px rgba(0,0,0,0.2);
}

/* 保持16:9宽高比 */
.video-container::before {
    content: "";
    display: block;
    padding-top: 56.25%; /* 9/16 = 0.5625 */
}

video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: contain; /* 完整显示视频内容 */
}



/* 动画关键帧 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.8);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes rotateLogo {
    from {
        transform: rotate(-180deg);
        opacity: 0;
    }
    to {
        transform: rotate(0);
        opacity: 1;
    }
}

/* 元素动画分配 */

.site-title {
    animation: fadeInUp 0.8s 0.3s ease-out both;
}

.nav-item {
    opacity: 0;
    animation: fadeInUp 0.6s 0.5s ease forwards;
}

.intro-text {
    opacity: 0;
    animation: fadeInUp 0.8s 0.7s ease forwards;
}

.video-container {
    opacity: 0;
    animation: scaleIn 0.8s 1s ease forwards;
}

/* 分阶段延迟 */
.nav-item:nth-child(1) { animation-delay: 0.5s; }
.nav-item:nth-child(2) { animation-delay: 0.6s; }
.nav-item:nth-child(3) { animation-delay: 0.7s; }
.nav-item:nth-child(4) { animation-delay: 0.8s; }
.nav-item:nth-child(5) { animation-delay: 0.9s; }
.nav-item:nth-child(6) { animation-delay: 1.0s; }
.nav-item:nth-child(7) { animation-delay: 1.1s; }
.nav-item:nth-child(8) { animation-delay: 1.2s; }

/* 滚动动画 */
@media (prefers-reduced-motion: no-preference) {
    .scroll-animate {
        opacity: 0;
        transform: translateY(30px);
        transition: all 0.6s ease;
    }

    .scroll-animate.visible {
        opacity: 1;
        transform: translateY(0);
    }
}