/* ==========================================================================
   Variables
   ========================================================================== */
:root {
    /* Color Palette */
    --primary: #6DA3B9;       /* 11 PB10 天(铁)蓝 */
    --primary-dark: #367D89;  /* 15 B09 */
    --primary-light: #A1D4C7; /* 14 B08 雅蓝 */
    --primary-bg: #CAEBE3;    /* 12 B06 */
    
    --accent: #F99996;        /* Pricing button color from Image 2 */
    --accent-hover: #fa807b;
    
    --bg-color: #F8FBFC;
    --bg-white: #ffffff;
    
    --text-main: #2B3A42;
    --text-light: #6C7A83;
    
    --border-color: #e5f0f3;
    
    /* Typography */
    --font-family: 'Inter', 'Roboto', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    
    /* Layout */
    --max-width: 1200px;
    --nav-height: 80px;
    
    /* Effects */
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    --shadow-sm: 0 2px 10px rgba(54, 125, 137, 0.05);
    --shadow-md: 0 8px 20px rgba(54, 125, 137, 0.1);
    --shadow-hover: 0 15px 35px rgba(54, 125, 137, 0.15);
}

/* ==========================================================================
   Reset & Base
   ========================================================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    color: var(--text-main);
    background-color: var(--bg-white);
    line-height: 1.6;
    overflow-x: hidden;
    scroll-behavior: smooth;
}

a {
    text-decoration: none;
    color: var(--primary-dark);
    transition: var(--transition);
}

ul, ol {
    list-style: none;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    padding: 90px 0;
}

.bg-light {
    background-color: var(--bg-color);
}

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

.mt-30 {
    margin-top: 30px;
}

/* Typography */
h1, h2, h3, h4, h5 {
    line-height: 1.2;
    margin-bottom: 15px;
    font-weight: 700;
}

.highlight {
    color: var(--primary);
}

.section-header {
    text-align: center;
    margin-bottom: 50px;
}

.section-header h2 {
    font-size: 36px;
    color: var(--text-main);
}

.section-header p {
    color: var(--text-light);
    font-size: 18px;
    max-width: 600px;
    margin: 0 auto;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 16px;
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid transparent;
}

.btn-primary {
    background-color: var(--primary);
    color: #fff;
    box-shadow: 0 4px 15px rgba(109, 163, 185, 0.4);
}

.btn-primary:hover {
    background-color: var(--primary-dark);
    color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(54, 125, 137, 0.4);
}

.btn-outline {
    background-color: transparent;
    color: var(--primary-dark);
    border-color: var(--primary-dark);
}

.btn-outline:hover {
    background-color: var(--primary-bg);
    transform: translateY(-2px);
}

/* ==========================================================================
   Navigation
   ========================================================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--nav-height);
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
    height: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 24px;
    font-weight: 800;
    color: var(--primary-dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo i {
    color: var(--primary);
}

.logo span {
    color: var(--text-main);
    font-size: 16px;
    font-weight: 400;
    opacity: 0.8;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 30px;
}

.nav-links a {
    color: var(--text-main);
    font-weight: 500;
    font-size: 15px;
    position: relative;
}

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

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

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

.nav-links .btn-nav {
    background-color: var(--primary-bg);
    color: var(--primary-dark);
    padding: 8px 20px;
    border-radius: 20px;
}

.nav-links .btn-nav::after {
    display: none;
}

.nav-links .btn-nav:hover {
    background-color: var(--primary);
    color: #fff;
}

.mobile-menu-btn {
    display: none;
    font-size: 24px;
    color: var(--text-main);
    cursor: pointer;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
    padding: 160px 20px 100px;
    background: linear-gradient(135deg, var(--bg-white) 0%, var(--bg-color) 100%);
    position: relative;
    overflow: hidden;
    text-align: center;
}

.hero-content {
    position: relative;
    z-index: 10;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 56px;
    color: var(--text-main);
    margin-bottom: 20px;
    letter-spacing: -1px;
}

.hero p {
    font-size: 20px;
    color: var(--text-light);
    margin-bottom: 40px;
}

.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 60px;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 10px;
    background: #fff;
    padding: 10px 25px;
    border-radius: 30px;
    box-shadow: var(--shadow-sm);
    font-weight: 600;
    color: var(--primary-dark);
}

.stat-item i {
    color: var(--primary);
}

/* Background Animation */
.hero-bg-animation {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: 1;
}

.circle {
    position: absolute;
    border-radius: 50%;
    background: radial-gradient(circle, var(--primary-light) 0%, rgba(161, 212, 199, 0) 70%);
    opacity: 0.5;
    animation: float 15s infinite ease-in-out alternate;
}

.circle-1 {
    width: 600px;
    height: 600px;
    top: -200px;
    left: -100px;
    animation-delay: 0s;
}

.circle-2 {
    width: 400px;
    height: 400px;
    bottom: -100px;
    right: -100px;
    background: radial-gradient(circle, var(--primary-bg) 0%, rgba(202, 235, 227, 0) 70%);
    animation-delay: -5s;
}

.circle-3 {
    width: 300px;
    height: 300px;
    top: 40%;
    left: 60%;
    background: radial-gradient(circle, rgba(109, 163, 185, 0.2) 0%, rgba(109, 163, 185, 0) 70%);
    animation-delay: -10s;
}

@keyframes float {
    0% { transform: translate(0, 0) scale(1); }
    100% { transform: translate(50px, 50px) scale(1.1); }
}

/* ==========================================================================
   Grid Layouts
   ========================================================================== */
.grid-4 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

/* ==========================================================================
   Advantages
   ========================================================================== */
.feature-card {
    background: #fff;
    padding: 40px 30px;
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-light);
}

.feature-icon {
    width: 70px;
    height: 70px;
    background-color: var(--primary-bg);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 0 auto 20px;
    font-size: 28px;
    color: var(--primary-dark);
    transition: var(--transition);
}

.feature-card:hover .feature-icon {
    background-color: var(--primary);
    color: #fff;
}

/* ==========================================================================
   Pricing Section (Matching Image 2)
   ========================================================================== */
.pricing-grid {
    display: flex;
    justify-content: center;
    gap: 30px;
    flex-wrap: wrap;
}

.pricing-card {
    background: #fff;
    border-radius: 8px;
    width: 100%;
    max-width: 350px;
    box-shadow: var(--shadow-sm);
    border: 1px solid #f0f0f0;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.pricing-card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-5px);
}

.pricing-header {
    padding: 30px;
    border-bottom: 1px solid #f0f0f0;
    text-align: center;
}

.pricing-header h3 {
    font-size: 20px;
    color: #333;
    margin-bottom: 20px;
}

.price {
    color: var(--primary-dark);
    margin-bottom: 20px;
    font-weight: bold;
}

.price .currency {
    font-size: 20px;
}

.price .amount {
    font-size: 40px;
}

.price .period {
    font-size: 14px;
    color: var(--text-light);
    font-weight: normal;
}

.btn-buy {
    display: block;
    width: 100%;
    padding: 12px 0;
    background-color: var(--primary-bg);
    color: var(--primary-dark);
    border: 1px solid var(--primary-light);
    border-radius: 4px;
    font-size: 16px;
    font-weight: 500;
    transition: var(--transition);
}

.btn-buy:hover {
    background-color: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

.pricing-body {
    padding: 30px;
    flex: 1;
}

.package-details, .package-instructions {
    margin-bottom: 25px;
}

.package-details h4, .package-instructions h4 {
    font-size: 14px;
    color: #333;
    margin-bottom: 15px;
}

.package-details ul {
    font-size: 13px;
    color: #666;
    line-height: 2;
}

.package-instructions ol {
    font-size: 13px;
    color: #666;
    line-height: 1.8;
    padding-left: 15px;
    list-style-type: decimal;
}

/* ==========================================================================
   Tutorials
   ========================================================================== */
.tutorial-grid {
    gap: 20px;
}

.tutorial-card {
    background: #fff;
    padding: 30px 20px;
    border-radius: 12px;
    text-align: center;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    display: block;
}

.tutorial-card:hover {
    background: var(--primary-bg);
    border-color: var(--primary-light);
}

.tutorial-icon {
    font-size: 40px;
    color: var(--primary);
    margin-bottom: 15px;
}

.tutorial-card h3 {
    color: var(--text-main);
    font-size: 18px;
    margin-bottom: 10px;
}

.tutorial-card p {
    color: var(--text-light);
    font-size: 14px;
}

/* ==========================================================================
   Knowledge Base
   ========================================================================== */
.article-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
    max-width: 900px;
    margin: 0 auto;
}

.article-item {
    display: flex;
    align-items: center;
    background: #fff;
    padding: 25px;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    border-left: 4px solid var(--primary-light);
    transition: var(--transition);
}

.article-item:hover {
    border-left-color: var(--primary);
    box-shadow: var(--shadow-md);
    transform: translateX(5px);
}

.article-date {
    min-width: 120px;
    color: var(--primary-dark);
    font-weight: 600;
    font-size: 14px;
}

.article-info h3 {
    margin-bottom: 5px;
    font-size: 18px;
}

.article-info h3 a {
    color: var(--text-main);
}

.article-info h3 a:hover {
    color: var(--primary);
}

.article-info p {
    color: var(--text-light);
    font-size: 14px;
    margin: 0;
}

/* ==========================================================================
   FAQ
   ========================================================================== */
.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

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

.faq-question {
    padding: 20px 25px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
}

.faq-question h4 {
    margin: 0;
    font-size: 16px;
}

.faq-question i {
    color: var(--primary);
    transition: transform 0.3s;
}

.faq-item.active .faq-question {
    background-color: var(--primary-bg);
    color: var(--primary-dark);
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
}

.faq-answer {
    padding: 0 25px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out, padding 0.3s ease;
    background-color: #fff;
    color: var(--text-light);
}

.faq-item.active .faq-answer {
    padding: 20px 25px;
    max-height: 500px;
    border-top: 1px solid var(--border-color);
}

/* ==========================================================================
   Reviews
   ========================================================================== */
.review-card {
    background: #fff;
    padding: 35px 30px;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.review-stars {
    color: #FFC107;
    margin-bottom: 15px;
}

.review-content {
    font-style: italic;
    color: var(--text-light);
    margin-bottom: 25px;
}

.review-author {
    display: flex;
    align-items: center;
    gap: 15px;
}

.author-avatar {
    font-size: 40px;
    color: var(--primary-bg);
}

.author-info h5 {
    margin: 0;
    font-size: 16px;
    color: var(--text-main);
}

.author-info span {
    font-size: 13px;
    color: var(--text-light);
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
    background-color: var(--text-main);
    color: #fff;
    padding: 60px 0 20px;
}

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

.footer-brand h3 {
    font-size: 24px;
    margin-bottom: 15px;
}

.footer-brand p {
    color: #a0aab2;
    font-size: 14px;
    max-width: 300px;
}

.footer-links h4 {
    font-size: 16px;
    margin-bottom: 20px;
    position: relative;
    padding-bottom: 10px;
}

.footer-links h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 30px;
    height: 2px;
    background-color: var(--primary);
}

.footer-links a {
    display: block;
    color: #a0aab2;
    margin-bottom: 10px;
    font-size: 14px;
}

.footer-links a:hover {
    color: var(--primary-light);
    padding-left: 5px;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: #8c97a0;
    font-size: 13px;
}

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    .mobile-menu-btn {
        display: block;
    }
    .hero h1 {
        font-size: 40px;
    }
    .hero-buttons {
        flex-direction: column;
    }
    .footer-content {
        grid-template-columns: 1fr;
    }
    .article-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
}