/* 基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --light-color: #ecf0f1;
    --dark-color: #2c3e50;
    --text-color: #333;
    --text-light: #666;
    --border-color: #ddd;
    --shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

body {
    font-family: 'Noto Sans SC', 'Poppins', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: #fff;
}

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

.section {
    padding: 80px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 15px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 3px;
    background-color: var(--secondary-color);
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 5px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: var(--transition);
    cursor: pointer;
    border: none;
    outline: none;
}

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

.btn-primary:hover {
    background-color: #2980b9;
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

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

.btn-secondary:hover {
    background-color: var(--secondary-color);
    color: white;
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

/* 导航栏 */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: white;
    box-shadow: var(--shadow);
    z-index: 1000;
    padding: 15px 0;
}

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

.logo {
    display: flex;
    flex-direction: column;
}

.logo-text {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary-color);
}

.logo-sub {
    font-size: 0.9rem;
    color: var(--secondary-color);
    font-weight: 600;
    letter-spacing: 2px;
}

.logo-tagline {
    font-size: 0.8rem;
    color: var(--text-light);
    margin-top: 2px;
}

.nav-menu {
    display: flex;
    gap: 30px;
}

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

.nav-link:hover,
.nav-link.active {
    color: var(--secondary-color);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--secondary-color);
}

.nav-contact {
    display: flex;
    align-items: center;
    gap: 20px;
}

.contact-info {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--secondary-color);
    font-weight: 600;
}

.btn-contact {
    padding: 8px 20px;
    background-color: var(--secondary-color);
    color: white;
    border: none;
    border-radius: 5px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.btn-contact:hover {
    background-color: #2980b9;
}

.mobile-menu-btn {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--primary-color);
}

/* 首页横幅 */
.hero {
    height: 100vh;
    background: linear-gradient(rgba(0, 0, 0, 0.7), rgba(0, 0, 0, 0.7)), 
                url('https://images.unsplash.com/photo-1581094794329-c8112a89af12?ixlib=rb-4.0.3&auto=format&fit=crop&w=1920&q=80');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    margin-top: 70px;
}

.hero-overlay {
    width: 100%;
    padding: 40px 0;
}

.hero-content {
    max-width: 800px;
    color: white;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.3rem;
    margin-bottom: 40px;
    opacity: 0.9;
}

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

/* 关于我们 */
.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.about-text h3 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.about-text p {
    margin-bottom: 20px;
    color: var(--text-light);
    line-height: 1.8;
}

.about-features {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    margin-top: 40px;
}

.feature {
    text-align: center;
    padding: 20px;
    border-radius: 10px;
    background-color: var(--light-color);
    transition: var(--transition);
}

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

.feature i {
    font-size: 2.5rem;
    color: var(--secondary-color);
    margin-bottom: 15px;
}

.feature h4 {
    font-size: 1.2rem;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.about-image img {
    width: 100%;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

/* 产品中心 */
.products-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.product-card {
    background-color: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.product-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

.product-image {
    height: 250px;
    overflow: hidden;
}

.product-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.product-card:hover .product-image img {
    transform: scale(1.1);
}

.product-content {
    padding: 30px;
}

.product-content h3 {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: 15px;
}

.product-content p {
    color: var(--text-light);
    margin-bottom: 20px;
}

.product-specs {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 20px;
}

.product-specs span {
    display: flex;
    align-items: center;
    gap: 5px;
    font-size: 0.9rem;
    color: var(--text-light);
}

.product-specs i {
    color: var(--secondary-color);
}

/* 材料分类 */
.materials-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.material-item {
    text-align: center;
    padding: 40px 20px;
    background-color: var(--light-color);
    border-radius: 10px;
    transition: var(--transition);
}

.material-item:hover {
    background-color: var(--secondary-color);
    color: white;
    transform: translateY(-5px);
}

.material-item:hover i,
.material-item:hover h4,
.material-item:hover p {
    color: white;
}

.material-item i {
    font-size: 3rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.material-item h4 {
    font-size: 1.3rem;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.material-item p {
    color: var(--text-light);
}

/* 应用领域 */
.applications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.application-card {
    text-align: center;
    padding: 40px 20px;
    background-color: white;
    border-radius: 10px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.application-card:hover {
    background-color: var(--secondary-color);
    color: white;
    transform: translateY(-5px);
}

.application-card:hover i,
.application-card:hover h4,
.application-card:hover p {
    color: white;
}

.application-card i {
    font-size: 3rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.application-card h4 {
    font-size: 1.3rem;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.application-card p {
    color: var(--text-light);
}

/* 联系我们 */
.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
}

.contact-info h3 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 30px;
}

.contact-details {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 15px;
}

.contact-item i {
    font-size: 1.5rem;
    color: var(--secondary-color);
    margin-top: 5px;
}

.contact-item h4 {
    font-size: 1.1rem;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.contact-item p {
    color: var(--text-light);
}

.contact-form h3 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 30px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-family: inherit;
    font-size: 1rem;
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
}

/* 页脚 */
.footer {
    background-color: var(--primary-color);
    color: white;
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
    margin-bottom: 40px;
}

.footer-logo h3 {
    font-size: 1.8rem;
    margin-bottom: 10px;
}

.footer-links h4,
.footer-contact h4 {
    font-size: 1.2rem;
    margin-bottom: 20px;
}

.footer-links a {
    display: block;
    color: #ddd;
    text-decoration: none;
    margin-bottom: 10px;
    transition: var(--transition);
}

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

.footer-contact p {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 15px;
    color: #ddd;
}

.footer-contact i {
    color: var(--secondary-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: #aaa;
    font-size: 0.9rem;
}

.footer-bottom a {
    color: #ddd;
    text-decoration: none;
}

.footer-bottom a:hover {
    color: var(--secondary-color);
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: var(--secondary-color);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.2rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background-color: var(--primary-color);
    transform: translateY(-5px);
}

/* 响应式设计 */
@media (max-width: 992px) {
    .hero-title {
        font-size: 2.8rem;
    }
    
    .about-content,
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .about-features {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .nav-contact {
        display: none;
    }
    
    .hero-title {
        font-size: 2.2rem;
    }
    
    .hero-subtitle {
        font-size: 1.1rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        gap: 15px;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .about-features {
        grid-template-columns: 1fr;
    }
    
    .products-grid {
        grid-template-columns: 1fr;
    }
    
    .materials-list,
    .applications-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 576px) {
    .materials-list,
    .applications-grid {
        grid-template-columns: 1fr;
    }
    
    .hero {
        height: 80vh;
    }
    
    .section {
        padding: 60px 0;
    }
}