/* ============================================
   快连 LetsVPN 落地页样式 - V2
   极简商务风格 - 明亮主题 + 科技蓝渐变
   ============================================ */

/* CSS 变量定义 */
:root {
    --color-primary: #0066FF;
    --color-primary-light: #3385FF;
    --color-primary-dark: #0052CC;
    --color-secondary: #00D4FF;
    --color-bg-light: #FFFFFF;
    --color-bg-dark: #F8F9FA;
    --color-text-dark: #212529;
    --color-text-light: #6C757D;
    --color-border: #E9ECEF;
    --color-accent: #28A745; /* 成功色 */
    --gradient-primary: linear-gradient(45deg, #0066FF 0%, #00D4FF 100%);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    --transition: all 0.3s ease-in-out;
}

/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
    background-color: var(--color-bg-light);
    color: var(--color-text-dark);
    line-height: 1.6;
    overflow-x: hidden;
}

/* 链接通用样式 */
a {
    color: var(--color-primary);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--color-primary-dark);
    text-decoration: underline;
}

/* 按钮通用样式 */
.btn {
    padding: 12px 28px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    opacity: 0.9;
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn-secondary:hover {
    background-color: rgba(0, 102, 255, 0.05);
    transform: translateY(-2px);
}

.btn-primary-outline {
    background-color: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
    padding: 8px 16px;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 500;
}

.btn-primary-outline:hover {
    background-color: var(--color-primary);
    color: white;
}

/* ============================================
   导航栏
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: var(--color-bg-light);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 22px;
    font-weight: 700;
    color: var(--color-text-dark);
}

.logo-icon {
    font-size: 28px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
    align-items: center;
}

.nav-link {
    color: var(--color-text-dark);
    text-decoration: none;
    font-size: 15px;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
}

.nav-link:hover {
    color: var(--color-primary);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: var(--transition);
}

.nav-link:hover::after {
    width: 100%;
}

.hamburger-menu {
    display: none; /* 默认隐藏，移动端显示 */
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.hamburger-menu span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--color-text-dark);
    border-radius: 3px;
    transition: var(--transition);
}

/* ============================================
   Hero 首屏
   ============================================ */
.hero {
    margin-top: 70px;
    padding: 100px 20px;
    background-color: var(--color-bg-dark);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 60px;
    min-height: 70vh;
    border-bottom: 1px solid var(--color-border);
}

.hero-content {
    max-width: 600px;
    text-align: left;
}

.hero-tagline {
    font-size: 14px;
    font-weight: 600;
    color: var(--color-primary);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 15px;
}

.hero-title {
    font-size: 48px;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 20px;
    color: var(--color-text-dark);
}

.gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 18px;
    color: var(--color-text-light);
    line-height: 1.7;
    margin-bottom: 40px;
}

.hero-actions {
    display: flex;
    gap: 20px;
    margin-bottom: 30px;
}

.hero-platforms p {
    font-size: 14px;
    color: var(--color-text-light);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.hero-image img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
}

/* ============================================
   Section 通用样式
   ============================================ */
section {
    padding: 80px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.section-badge {
    display: inline-block;
    background-color: rgba(0, 102, 255, 0.1);
    color: var(--color-primary);
    padding: 8px 18px;
    border-radius: 25px;
    font-size: 13px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    margin-bottom: 15px;
}

.section-header h2 {
    font-size: 38px;
    font-weight: 700;
    margin-bottom: 15px;
    color: var(--color-text-dark);
}

.section-header p {
    font-size: 17px;
    color: var(--color-text-light);
    line-height: 1.8;
}

/* ============================================
   核心价值
   ============================================ */
.value-proposition {
    background-color: var(--color-bg-light);
}

.value-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.value-item {
    background-color: var(--color-bg-dark);
    border: 1px solid var(--color-border);
    padding: 35px;
    border-radius: 12px;
    text-align: center;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.value-item:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary);
}

.value-icon {
    font-size: 48px;
    margin-bottom: 20px;
}

.value-item h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--color-text-dark);
}

.value-item p {
    font-size: 15px;
    color: var(--color-text-light);
    line-height: 1.7;
}

/* ============================================
   技术深度解析
   ============================================ */
.tech-deep-dive {
    background-color: var(--color-bg-dark);
}

.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.tech-card {
    background-color: var(--color-bg-light);
    border: 1px solid var(--color-border);
    padding: 40px;
    border-radius: 12px;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.tech-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary);
}

.tech-icon {
    font-size: 48px;
    margin-bottom: 20px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tech-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--color-text-dark);
}

.tech-card p {
    font-size: 15px;
    color: var(--color-text-light);
    line-height: 1.7;
}

/* ============================================
   产品对比表格
   ============================================ */
.product-comparison {
    background-color: var(--color-bg-light);
}

.table-responsive {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--color-bg-dark);
    border: 1px solid var(--color-border);
    border-radius: 12px;
    overflow: hidden;
    min-width: 700px; /* 确保在小屏幕下表格不会太窄 */
}

.comparison-table thead {
    background-color: var(--color-primary);
    color: white;
}

.comparison-table th {
    padding: 18px 25px;
    text-align: left;
    font-weight: 600;
    font-size: 15px;
}

.comparison-table tbody tr {
    border-bottom: 1px solid var(--color-border);
}

.comparison-table tbody tr:last-child {
    border-bottom: none;
}

.comparison-table td {
    padding: 15px 25px;
    font-size: 15px;
    color: var(--color-text-dark);
}

.comparison-table tbody tr:nth-child(even) {
    background-color: #F0F3F6;
}

.comparison-table td:first-child {
    font-weight: 600;
    color: var(--color-primary-dark);
}

/* ============================================
   应用场景
   ============================================ */
.use-cases {
    background-color: var(--color-bg-dark);
}

.scenario-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.scenario-card {
    background-color: var(--color-bg-light);
    border: 1px solid var(--color-border);
    padding: 35px;
    border-radius: 12px;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.scenario-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary);
}

.scenario-icon {
    font-size: 48px;
    margin-bottom: 20px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.scenario-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--color-text-dark);
}

.scenario-card p {
    font-size: 15px;
    color: var(--color-text-light);
    line-height: 1.7;
}

/* ============================================
   用户评价
   ============================================ */
.customer-reviews {
    background-color: var(--color-bg-light);
}

.review-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.review-card {
    background-color: var(--color-bg-dark);
    border: 1px solid var(--color-border);
    padding: 30px;
    border-radius: 12px;
    font-style: italic;
    color: var(--color-text-dark);
    line-height: 1.7;
    position: relative;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.review-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary);
}

.review-card p {
    font-size: 16px;
    margin-bottom: 20px;
}

.review-card cite {
    display: block;
    font-style: normal;
    font-weight: 600;
    color: var(--color-primary-dark);
    font-size: 14px;
}

/* ============================================
   FAQ
   ============================================ */
.faq-section {
    background-color: var(--color-bg-dark);
}

.faq-container {
    max-width: 900px;
    margin: 0 auto;
}

.faq-item {
    background-color: var(--color-bg-light);
    border: 1px solid var(--color-border);
    margin-bottom: 15px;
    border-radius: 8px;
    overflow: hidden;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.faq-item:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
}

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    cursor: pointer;
    font-weight: 600;
    color: var(--color-text-dark);
    font-size: 16px;
    user-select: none;
}

.faq-question::after {
    content: '▼';
    transition: var(--transition);
    color: var(--color-primary);
    font-size: 14px;
}

.faq-item[open] .faq-question::after {
    transform: rotate(180deg);
}

.faq-answer {
    padding: 0 20px 20px 20px;
    color: var(--color-text-light);
    font-size: 15px;
    line-height: 1.7;
}

.faq-answer p {
    margin-bottom: 12px;
}

.faq-answer ul {
    margin-left: 25px;
    margin-bottom: 12px;
    list-style-type: disc;
}

.faq-answer li {
    margin-bottom: 8px;
}

/* ============================================
   下载区
   ============================================ */
.download-section {
    background: var(--gradient-primary);
    text-align: center;
    padding: 80px 20px;
    color: white;
}

.download-section .section-header {
    color: white;
}

.download-section .section-badge {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
    border-color: rgba(255, 255, 255, 0.5);
}

.download-section h2 {
    color: white;
}

.download-section p {
    color: rgba(255, 255, 255, 0.9);
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 20px;
    max-width: 1000px;
    margin: 40px auto 0;
}

.download-card {
    background-color: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.3);
    padding: 25px 15px;
    border-radius: 12px;
    text-decoration: none;
    color: white;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.download-card:hover {
    background-color: rgba(255, 255, 255, 0.2);
    border-color: white;
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.download-icon {
    font-size: 42px;
    margin-bottom: 12px;
}

.download-card h3 {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 5px;
}

.download-card p {
    font-size: 12px;
    color: rgba(255, 255, 255, 0.8);
}

/* ============================================
   页脚
   ============================================ */
.footer {
    background-color: var(--color-text-dark);
    color: white;
    padding: 60px 20px 20px;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h4 {
    font-size: 16px;
    font-weight: 700;
    color: var(--color-primary-light);
    margin-bottom: 20px;
}

.footer-col ul {
    list-style: none;
}

.footer-col ul li {
    margin-bottom: 10px;
}

.footer-col a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    font-size: 14px;
}

.footer-col a:hover {
    color: white;
    text-decoration: underline;
}

.footer-col p {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 10px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 22px;
    font-weight: 700;
    color: white;
    margin-bottom: 15px;
}

.footer-logo .logo-icon {
    font-size: 28px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.social-links a {
    display: inline-block;
    margin-right: 15px;
}

.social-links img {
    width: 24px;
    height: 24px;
    vertical-align: middle;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    color: rgba(255, 255, 255, 0.6);
    font-size: 13px;
}

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 992px) {
    .hero {
        flex-direction: column-reverse;
        text-align: center;
        gap: 40px;
        padding: 80px 20px;
    }

    .hero-content {
        max-width: 100%;
        text-align: center;
    }

    .hero-title {
        font-size: 40px;
    }

    .hero-description {
        font-size: 16px;
    }

    .hero-actions {
        justify-content: center;
    }

    .hero-image {
        max-width: 80%;
    }

    .nav-menu {
        display: none;
    }

    .hamburger-menu {
        display: flex;
    }

    .section-header h2 {
        font-size: 32px;
    }

    .value-grid, .tech-grid, .scenario-grid, .review-grid, .download-grid {
        grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    }

    .footer-container {
        grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    }
}

@media (max-width: 768px) {
    .hero {
        padding: 60px 20px;
    }

    .hero-title {
        font-size: 32px;
    }

    .hero-description {
        font-size: 15px;
    }

    .hero-actions {
        flex-direction: column;
        gap: 15px;
    }

    .btn {
        width: 100%;
    }

    .section-header h2 {
        font-size: 28px;
    }

    .section-header p {
        font-size: 15px;
    }

    .comparison-table {
        min-width: 600px;
    }

    .footer-container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-col ul {
        padding-left: 0;
    }

    .footer-col ul li {
        display: inline-block;
        margin: 0 10px;
    }

    .footer-logo {
        justify-content: center;
    }

    .social-links {
        margin-top: 20px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 28px;
    }

    .hero-image {
        max-width: 90%;
    }

    .section-header h2 {
        font-size: 24px;
    }

    .value-grid, .tech-grid, .scenario-grid, .review-grid, .download-grid {
        grid-template-columns: 1fr;
    }

    .comparison-table {
        min-width: 500px;
    }

    .download-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}