/* 全局重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Microsoft YaHei", sans-serif;
}

/* 高级清冷科技配色变量 */
:root {
    --primary: #2E6BFF;
    --secondary: #60A5FA;
    --dark: #121A2E;
    --light: #ffffff;
    --gray: #F7F9FC;
    --text-dark: #1F2937;
    --text-gray: #4B5563;
    --line-color: #D1D5DB;
    --star-color: #FBBF24;
    --shadow: 0 8px 25px rgba(46, 107, 255, 0.1);
}

body {
    background-color: var(--gray);
    color: var(--text-gray);
    line-height: 1.6;
}

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

a {
    text-decoration: none;
}

.btn {
    display: inline-block;
    padding: 14px 36px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    color: #fff;
    border-radius: 50px;
    font-weight: bold;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    text-align: center;
}

.btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(46, 107, 255, 0.25);
}

.section {
    padding: 80px 0;
}

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

.section-header h3 {
    font-size: 32px;
    color: var(--text-dark);
    margin-bottom: 15px;
    position: relative;
    display: inline-block;
}

.line {
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    margin: 0 auto;
    border-radius: 2px;
}

/* 导航栏 */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.97);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
    z-index: 999;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo h1 {
    color: var(--primary);
    font-size: 24px;
}

.nav-menu {
    display: flex;
    gap: 35px;
}

.nav-link {
    color: var(--text-gray);
    font-weight: 500;
    transition: 0.3s;
}

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

/* Banner */
.banner {
    height: 100vh;
    background: linear-gradient(rgba(18, 26, 46, 0.85), rgba(18, 26, 46, 0.9)), url('banner-bg.jpg') center/cover no-repeat;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
    margin-top: 70px;
}

.banner-title {
    font-size: 48px;
    margin-bottom: 20px;
}

.banner-desc {
    font-size: 20px;
    margin-bottom: 35px;
    opacity: 0.9;
}

/* 网站简介 */
.about {
    background: #ffffff;
}

.about-content {
    max-width: 900px;
    margin: 0 auto;
    text-align: justify;
    text-align-last: center;
    font-size: 17px;
    line-height: 1.9;
}

.about-content p {
    margin-bottom: 20px;
    text-indent: 2em;
}

/* 网站优势 */
.advantage {
    background: var(--gray);
}

.advantage-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
}

.advantage-item {
    background: #fff;
    padding: 40px 25px;
    border-radius: 15px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: 0.3s;
}

.advantage-item:hover {
    transform: translateY(-8px);
}

.advantage-item i {
    font-size: 40px;
    color: var(--primary);
    margin-bottom: 20px;
}

.advantage-item h4 {
    font-size: 20px;
    color: var(--text-dark);
    margin-bottom: 12px;
}

/* 用户评价 */
.review {
    background: #ffffff;
}

.review-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
}

.review-card {
    background: var(--gray);
    padding: 35px;
    border-radius: 15px;
    box-shadow: var(--shadow);
}

.stars {
    color: var(--star-color);
    margin-bottom: 15px;
    font-size: 16px;
}

.review-card p {
    font-size: 16px;
    margin-bottom: 15px;
    line-height: 1.8;
}

.review-card h5 {
    color: var(--primary);
    font-size: 16px;
    font-weight: bold;
}

/* 资源介绍 */
.resource {
    background: var(--gray);
}

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

.resource-card {
    background: #fff;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease;
}

.resource-card:hover {
    transform: translateY(-6px);
}

.resource-card-img img {
    width: 100%;
    height: 220px;
    object-fit: cover;
    display: block;
}

.resource-card-info {
    padding: 24px;
}

.resource-card-info h4 {
    font-size: 20px;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.resource-card-info p {
    font-size: 15px;
    line-height: 1.7;
    color: var(--text-gray);
    margin-bottom: 20px;
    text-align: justify;
}

.resource-card-info .download-btn {
    width: 100%;
    text-align: center;
    padding: 12px 0;
}

/* 底部 */
.footer {
    background: var(--dark);
    color: #fff;
    text-align: center;
    padding: 30px 0;
}

/* 自适应 */
@media (max-width: 992px) {
    .advantage-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .resource-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .banner-title {
        font-size: 32px;
    }
    .nav-menu {
        display: none;
    }
    .review-grid {
        grid-template-columns: 1fr;
    }
    .resource-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 576px) {
    .section {
        padding: 60px 0;
    }
    .section-header h3 {
        font-size: 26px;
    }
}