/* =========================================
   1. Root & Reset
   ========================================= */
:root {
    /* Brand Colors */
    --color-primary: #2c3e50;    /* 深邃蓝 - 理性/系统 */
    --color-secondary: #e67e22;  /* 活力橙 - 突破/成长 */
    --color-accent: #3498db;     /* 科技蓝 - 句法/逻辑 */
    --color-text: #2d3436;
    --color-text-light: #636e72;
    --bg-surface: #fdfbf7;       /* 沿用 Seminar 页面的暖白纸张色 */
    --bg-white: #ffffff;
    
    /* Card Themes */
    --theme-syntax: #2980b9;
    --theme-writing: #c0392b;
    --theme-speaking: #8e44ad;
    --theme-seminar: #27ae60;

    /* Layout */
    --container-width: 1140px;
    --header-height: 70px;
    
    /* Effects */
    --shadow-sm: 0 4px 6px rgba(0,0,0,0.05);
    --shadow-md: 0 10px 30px rgba(0,0,0,0.08);
    --shadow-lg: 0 20px 50px rgba(0,0,0,0.12);
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Noto Sans SC', sans-serif;
    background-color: var(--bg-surface);
    color: var(--color-text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a { text-decoration: none; color: inherit; transition: var(--transition); }
h1, h2, h3 { font-family: 'Playfair Display', serif; font-weight: 700; color: var(--color-primary); }

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* =========================================
   2. Header
   ========================================= */
.site-header {
    position: fixed;
    top: 0; left: 0; width: 100%;
    height: var(--header-height);
    background: rgba(253, 251, 247, 0.85);
    backdrop-filter: blur(12px);
    z-index: 1000;
    border-bottom: 1px solid rgba(0,0,0,0.05);
    display: flex;
    align-items: center;
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.logo {
    font-family: 'Playfair Display', serif;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: 8px;
}

.badge-beta {
    font-family: sans-serif;
    font-size: 0.7rem;
    background: var(--color-primary);
    color: #fff;
    padding: 2px 6px;
    border-radius: 4px;
    letter-spacing: 1px;
}

.main-nav {
    display: flex;
    gap: 32px;
}

.main-nav a {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text);
    position: relative;
}

.main-nav a:hover { color: var(--color-secondary); }

.btn-login {
    background: var(--color-primary);
    color: #fff;
    padding: 8px 20px;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 600;
}

.btn-login:hover {
    background: var(--color-secondary);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(230, 126, 34, 0.3);
}

/* =========================================
   3. Hero Section
   ========================================= */
.hero-section {
    position: relative;
    height: 90vh;
    min-height: 600px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding-top: var(--header-height);
    overflow: hidden;
}

/* 抽象背景图案 */
.hero-bg-pattern {
    position: absolute;
    top: -50%; right: -50%;
    width: 200%; height: 200%;
    background: radial-gradient(circle, rgba(52, 152, 219, 0.05) 0%, rgba(253,251,247,0) 60%);
    animation: rotate 60s linear infinite;
    z-index: -1;
}

@keyframes rotate { from { transform: rotate(0deg); } to { transform: rotate(360deg); } }

.hero-subtitle {
    display: block;
    font-size: 0.85rem;
    letter-spacing: 3px;
    text-transform: uppercase;
    color: var(--color-secondary);
    margin-bottom: 20px;
    font-weight: 700;
}

.hero-title {
    font-size: 3.5rem;
    line-height: 1.1;
    margin-bottom: 30px;
}

.highlight {
    color: var(--color-secondary);
    position: relative;
    display: inline-block;
}

/* 下划线装饰 */
.highlight::after {
    content: '';
    position: absolute;
    bottom: 5px; left: 0; width: 100%; height: 10px;
    background: rgba(230, 126, 34, 0.2);
    z-index: -1;
    transform: skewX(-10deg);
}

.hero-desc {
    font-size: 1.2rem;
    color: var(--color-text-light);
    max-width: 700px;
    margin: 0 auto 50px;
}

.hero-actions {
    display: flex;
    gap: 20px;
}

.btn {
    padding: 15px 40px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
}

.btn-primary {
    background: var(--color-primary);
    color: #fff;
    box-shadow: 0 10px 20px rgba(44, 62, 80, 0.3);
}

.btn-primary:hover {
    background: #34495e;
    transform: translateY(-3px);
    box-shadow: 0 15px 30px rgba(44, 62, 80, 0.4);
}

.btn-secondary {
    background: #fff;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.btn-secondary:hover {
    background: #f1f2f6;
}

.scroll-indicator {
    position: absolute;
    bottom: 40px;
    display: flex;
    flex-direction: column;
    align-items: center;
    font-size: 0.8rem;
    color: #b2bec3;
    animation: bounce 2s infinite;
}

@keyframes bounce { 0%, 20%, 50%, 80%, 100% {transform: translateY(0);} 40% {transform: translateY(-10px);} 60% {transform: translateY(-5px);} }

/* =========================================
   4. Methodology (Cards)
   ========================================= */
.methodology-section {
    padding: 100px 0;
    background: var(--bg-white);
}

.section-header {
    text-align: center;
    margin-bottom: 70px;
}

.section-header h2 { font-size: 2.5rem; margin-bottom: 10px; }
.section-header p { font-size: 1.1rem; color: var(--color-text-light); }

.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 30px;
}

.feature-card {
    background: #fff;
    border-radius: 16px;
    padding: 40px 30px;
    border: 1px solid rgba(0,0,0,0.05);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    height: 100%;
}

/* 卡片顶部彩色线条 */
.feature-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; width: 100%; height: 5px;
    transition: var(--transition);
}

.syntax-theme::before { background: var(--theme-syntax); }
.writing-theme::before { background: var(--theme-writing); }
.speaking-theme::before { background: var(--theme-speaking); }
.seminar-theme::before { background: var(--theme-seminar); }

/* 卡片悬停效果 */
.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
    border-color: transparent;
}

.card-icon-wrapper {
    width: 60px; height: 60px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    margin-bottom: 25px;
    background: #f8f9fa;
    transition: var(--transition);
}

/* 悬停时图标变色 */
.syntax-theme:hover .card-icon-wrapper { background: rgba(41, 128, 185, 0.1); color: var(--theme-syntax); }
.writing-theme:hover .card-icon-wrapper { background: rgba(192, 57, 43, 0.1); color: var(--theme-writing); }
.speaking-theme:hover .card-icon-wrapper { background: rgba(142, 68, 173, 0.1); color: var(--theme-speaking); }
.seminar-theme:hover .card-icon-wrapper { background: rgba(39, 174, 96, 0.1); color: var(--theme-seminar); }

.card-tag {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    color: #b2bec3;
    margin-bottom: 10px;
    display: block;
}

.feature-card h3 { font-size: 1.5rem; margin-bottom: 15px; color: var(--color-text); }
.feature-card p { font-size: 0.95rem; color: var(--color-text-light); margin-bottom: 25px; flex-grow: 1; }

.link-text {
    font-weight: 700;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 8px;
    opacity: 0.8;
}

.syntax-theme .link-text { color: var(--theme-syntax); }
.writing-theme .link-text { color: var(--theme-writing); }
.speaking-theme .link-text { color: var(--theme-speaking); }
.seminar-theme .link-text { color: var(--theme-seminar); }

/* 原著研讨卡片的特殊发光效果 (Featured) */
.featured-glow {
    border: 1px solid rgba(39, 174, 96, 0.2);
    background: linear-gradient(to bottom, #fff, #fafffc);
}

/* =========================================
   5. Stats Section
   ========================================= */
.stats-section {
    background-color: var(--color-primary);
    padding: 60px 0;
    color: #fff;
    margin-top: 50px;
}

.stats-wrapper {
    display: flex;
    justify-content: space-around;
    align-items: center;
    flex-wrap: wrap;
    gap: 40px;
}

.stat-box { text-align: center; }

.stat-number {
    font-family: 'Playfair Display', serif;
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--color-secondary);
    line-height: 1;
    margin-bottom: 5px;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.8;
    letter-spacing: 1px;
}

.divider {
    width: 1px; height: 60px;
    background: rgba(255,255,255,0.1);
}

/* =========================================
   6. Leader Section (Updated)
   ========================================= */
.leader-section {
    padding: 100px 0;
}

.leader-card {
    background: #fff;
    border-radius: 20px;
    padding: 60px;
    box-shadow: var(--shadow-md);
    border: 1px solid #eee;
    
    /* Flex Layout */
    display: flex;
    align-items: flex-start; /* 顶部对齐，如果文字多的话比 center 更好 */
    gap: 60px; /* 使用 gap 代替 margin，控制图片和文字间距 */
}

/* 头像区域 */
.leader-visual {
    flex-shrink: 0; /* 防止图片被压缩 */
}

.leader-avatar-img {
    width: 160px;       /* PC端尺寸 */
    height: 160px;
    border-radius: 50%;
    object-fit: cover;  /* 确保剪裁正确 */
    
    /* 装饰效果 */
    box-shadow: 0 10px 25px rgba(230, 126, 34, 0.2);
    border: 4px solid #fff; 
    transition: transform 0.3s ease;
}

.leader-avatar-img:hover {
    transform: scale(1.05) rotate(2deg); /* 微微互动 */
}

/* 文字区域 */
.leader-info {
    flex-grow: 1;
}

/* 头衔样式 */
.leader-titles {
    margin-bottom: 1.5rem;
}

.leader-titles .main-title {
    display: block;
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--color-secondary); /* 呼应主题色 */
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
}

.leader-titles .title-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.leader-titles .title-list li {
    font-size: 0.85rem;
    color: #666;
    line-height: 1.5;
    margin-bottom: 2px;
}

.leader-titles .title-list li strong {
    color: #333;
    font-weight: 600;
}

/* 名字和正文 */
.leader-info h3 { 
    font-size: 2.2rem; 
    margin-bottom: 20px; 
    color: var(--color-primary);
}

.leader-philosophy {
    margin-top: 1.5rem;
    border-top: 1px solid #eee;
    padding-top: 1.5rem;
}

.quote-style {
    font-family: 'Playfair Display', serif;
    font-style: italic;
    font-size: 1.1rem;
    color: #2c3e50;
    margin-bottom: 1rem;
}

.leader-bio {
    font-size: 0.95rem;
    color: #555;
    line-height: 1.6;
    margin-bottom: 0.8rem;
}

.leader-links {
    margin-top: 25px;
}

.leader-links a {
    color: var(--color-primary);
    font-weight: 700;
    border-bottom: 2px solid transparent;
}

.leader-links a:hover {
    color: var(--color-secondary);
    border-bottom-color: var(--color-secondary);
}

/* =========================================
   7. Footer
   ========================================= */
.main-footer {
    background: #fff;
    border-top: 1px solid #eee;
    padding: 60px 0 20px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h4 {
    font-size: 1rem;
    margin-bottom: 20px;
    color: var(--color-primary);
}

.footer-col p, .footer-col a {
    display: block;
    color: var(--color-text-light);
    font-size: 0.9rem;
    margin-bottom: 10px;
}

.footer-col a:hover { color: var(--color-primary); }

.footer-bottom {
    text-align: center;
    font-size: 0.8rem;
    color: #b2bec3;
    padding-top: 20px;
    border-top: 1px solid #f8f9fa;
}

/* =========================================
   MOBILE RESPONSIVE (APP-LIKE EXPERIENCE)
   ========================================= */
@media (max-width: 768px) {
    
    /* --- 1. 全局基础体验优化 --- */
    body {
        font-size: 16px; /* 增大字号，防止iOS自动缩放 */
    }

    .container {
        padding-left: 20px;
        padding-right: 20px;
        width: 100%; /* 占满手机宽度 */
    }

    p {
        font-size: 1rem;
        line-height: 1.7; /* 增加行距，提升阅读舒适度 */
        text-align: justify; /* 两端对齐，看起来更整齐 */
    }

    /* --- 2. 头部与导航 (APP式横向滑动) --- */
    .header-inner {
        flex-direction: column; /* Logo在上，菜单在下 */
        gap: 15px;
        padding: 15px 0;
    }

    .logo {
        margin-right: 0; /* Logo居中 */
        justify-content: center;
    }

    /* 关键修改：不隐藏菜单，而是变成横向滑动条 */
    .main-nav {
        display: flex; /* 恢复显示 */
        width: 100%;
        overflow-x: auto; /* 允许横向滑动 */
        white-space: nowrap; /* 强制不换行 */
        padding-bottom: 5px; /* 预留滑动条空间 */
        gap: 15px;
        -webkit-overflow-scrolling: touch; /* iOS丝滑滚动体验 */
        justify-content: flex-start; /* 从左开始排 */
        
        /* 隐藏滚动条但保留功能 (Chrome/Safari) */
        scrollbar-width: none; 
        -ms-overflow-style: none;
    }
    .main-nav::-webkit-scrollbar {
        display: none;
    }

    .main-nav a {
        font-size: 0.9rem;
        padding: 8px 15px;
        background: rgba(0,0,0,0.04); /* 按钮化背景 */
        border-radius: 20px; /* 胶囊形状 */
        color: #555;
    }

    /* 隐藏顶部的大登录按钮，防止占地，假设菜单里有入口或用小图标 */
    .header-inner .btn-login {
        display: none; 
    }

    /* --- 3. Hero 区域 (视觉中心) --- */
    .hero-section {
        padding-top: 120px; /* 避开加高的头部 */
    }

    .hero-content {
        text-align: center; /* 居中更有气势 */
        padding-top: 20px;
    }

    .hero-title {
        font-size: 2.2rem; /*稍微调小防止换行太碎 */
        line-height: 1.3;
    }

    .hero-actions {
        flex-direction: column; /* 按钮垂直堆叠 */
        width: 100%;
        gap: 15px;
    }

    .btn {
        width: 100%; /* 按钮撑满全宽，方便手指点击 */
        text-align: center;
        padding: 15px;
    }

    /* --- 4. 数据统计区 (Stacking) --- */
    .stats-wrapper {
        flex-direction: column;
        gap: 20px;
    }

    .divider {
        width: 60px;
        height: 1px;
        margin: 10px auto; /* 居中分割线 */
        background: #eee;
    }

    /* --- 5. 负责人/教授板块 (精细调整) --- */
    .leader-card {
        flex-direction: column;
        text-align: center;
        padding: 40px 20px;
        gap: 30px;
    }

    .leader-visual {
        margin-right: 0;
        width: 100%;
        display: flex;
        justify-content: center;
    }

    .leader-avatar-img {
        width: 160px;
        height: 160px;
        border-radius: 50%;
        object-fit: cover;
        
        /* 核心保留：防止头像被切掉头顶 */
        object-position: top; 
        
        box-shadow: 0 10px 25px rgba(230, 126, 34, 0.2);
        border: 4px solid #fff;
    }

    .leader-links {
        width: 100%;
    }
    
    .leader-links a {
        display: block; /* 链接变块级，方便点击 */
        padding: 10px;
        background: #f9f9f9;
        border-radius: 8px;
    }

    /* --- 6. 页脚 (堆叠布局) --- */
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 40px;
    }

    .copyright-bar {
        flex-direction: column;
        text-align: center;
        gap: 20px;
    }

    .tech-side {
        text-align: center;
    }

    .beian-container {
        justify-content: center !important;
        margin-top: 10px;
    }
}