/* --- 全新的现代风格 --- */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@300;400;500;700&display=swap');

:root {
    --primary-color: #007BFF; /* 主题蓝 */
    --secondary-color: #495057; /* 深灰色文本 */
    --background-color: #f8f9fa; /* 淡灰色背景 */
    --surface-color: #ffffff; /* 卡片和表单背景 */
    --accent-color: #28a745; /* 强调绿 */
    --border-color: #dee2e6; /* 边框颜色 */
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    --border-radius: 12px;
    --font-family: 'Noto Sans SC', sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--secondary-color);
    line-height: 1.7;
}

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

/* --- 统一头部 --- */
.header {
    text-align: center;
    padding: 50px 20px;
    background: linear-gradient(135deg, var(--primary-color), #0056b3);
    color: var(--surface-color);
    border-radius: 0 0 var(--border-radius) var(--border-radius);
    margin-bottom: 30px;
}

.header .logo {
    font-size: 48px;
    margin-bottom: 15px;
}

.header .title {
    font-size: 2.2rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.header .subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* --- 广告位 --- */
.ad-banner {
    /*margin: 20px 0;*/
    /*padding: 15px;*/
    /*background-color: var(--surface-color);*/
    /*border-radius: var(--border-radius);*/
    /*box-shadow: var(--shadow);*/
    /*display: flex;*/
    /*justify-content: center;*/
    /*align-items: center;*/
}

/* --- 移动端导航 --- */
.mobile-nav {
    display: none; /* 默认桌面端不显示 */
    background-color: var(--surface-color);
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.mobile-nav-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.mobile-logo {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--primary-color);
    text-decoration: none;
}

.menu-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--secondary-color);
    cursor: pointer;
}

.mobile-menu {
    display: none;
    flex-direction: column;
    background-color: var(--surface-color);
    border-top: 1px solid var(--border-color);
}

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

.mobile-menu-item {
    padding: 15px 20px;
    text-decoration: none;
    color: var(--secondary-color);
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.3s;
}

.mobile-menu-item.active, .mobile-menu-item:hover {
    background-color: var(--background-color);
    color: var(--primary-color);
}

.mobile-menu-item i {
    margin-right: 10px;
}

/* --- 底部导航 --- */
.bottom-nav {
    display: none; /* 默认桌面端不显示 */
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background-color: var(--surface-color);
    box-shadow: 0 -2px 8px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-around;
    z-index: 1000;
}

.bottom-nav-item {
    flex: 1;
    padding: 10px 0;
    text-align: center;
    text-decoration: none;
    color: var(--secondary-color);
    transition: color 0.3s;
}

.bottom-nav-item.active, .bottom-nav-item:hover {
    color: var(--primary-color);
}

.bottom-nav-item i {
    display: block;
    font-size: 1.4rem;
    margin-bottom: 4px;
}

.bottom-nav-item span {
    font-size: 0.8rem;
}

/* --- 卡片样式 --- */
.category-grid, .tutorial-list, .service-content, .service-commitment {
    padding: 0 15px;
}

.category-card, .tutorial-item, .service-entry, .commitment-item {
    background-color: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 20px;
    padding: 25px;
    transition: transform 0.3s, box-shadow 0.3s;
    text-decoration: none;
    color: var(--secondary-color);
    display: block;
}

.category-card:hover, .tutorial-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.12);
}

.category-title, .tutorial-title {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.category-desc, .tutorial-desc {
    font-size: 1rem;
    margin-bottom: 15px;
}

.view-btn, .tutorial-btn, .service-btn {
    display: inline-block;
    padding: 10px 20px;
    background-color: var(--primary-color);
    color: var(--surface-color);
    text-decoration: none;
    border-radius: 8px;
    font-weight: 500;
    transition: background-color 0.3s;
}

.view-btn:hover, .tutorial-btn:hover, .service-btn:hover {
    background-color: #0056b3;
}

/* --- FAQ 特定样式 --- */
.tutorial-header {
    display: flex;
    align-items: center;
    margin-bottom: 15px;
}

.tutorial-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-right: 15px;
}

.tutorial-duration {
    margin-left: auto;
    font-size: 0.9rem;
    color: #6c757d;
}

/* --- 客服页面 --- */
.service-contact {
    text-align: center;
    margin-top: 20px;
}

.service-commitment-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-top: 30px;
}

.commitment-icon {
    font-size: 2.5rem;
    color: var(--accent-color);
    margin-bottom: 10px;
}

/* --- 响应式设计 --- */
@media (max-width: 768px) {
    body {
        padding-bottom: 70px; /* 为底部导航栏留出空间 */
    }

    .mobile-nav {
        display: block;
    }

    .bottom-nav {
        display: flex;
    }

    .header {
        padding: 40px 15px;
    }

    .header .title {
        font-size: 1.8rem;
    }

    .header .subtitle {
        font-size: 1rem;
    }

    .container {
        padding: 0;
    }
}

/* --- 其他 --- */
.back-btn {
    display: inline-block;
    margin: 20px;
    padding: 8px 16px;
    background: var(--surface-color);
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 8px;
    box-shadow: var(--shadow);
    font-weight: 500;
}

.float-customer-service {
    position: fixed;
    bottom: 80px;
    right: 20px;
    background-color: var(--accent-color);
    color: white;
    padding: 12px;
    border-radius: 50%;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
}

.float-service-icon {
    width: 28px;
    height: 28px;
}

.float-service-text {
    display: none; /* 简化为图标 */
}

/* 加载动画 */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    padding: 40px;
}