/* 全局变量与基础重置 */
:root {
    --primary-color: #0056b3;
    --secondary-color: #007bff;
    --dark-color: #333;
    --light-color: #f4f4f4;
    --header-bg: #fff;
    --header-text: #333;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
}

/* 布局工具 */
.container {
    max-width: 1100px;
    margin: auto;
    padding: 0 20px;
}
.section {
    padding: 4rem 0;
}
.text-center {
    text-align: center;
}
.bg-light {
    background: var(--light-color);
}
.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: var(--dark-color);
}

/* 导航栏 */
header {
    background: var(--header-bg);
    color: var(--header-text);
    padding: 0.5rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid #eaeaea;
}
.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo-link {
    display: flex;
    align-items: center;
}
.logo-img {
    height: 85px;
    width: auto;
    display: block;
    background: transparent;
    border: none;
}
nav {
    display: flex;
    align-items: center;
}
nav a {
    color: var(--header-text);
    text-decoration: none;
    margin-left: 20px;
    font-size: 1rem;
    transition: color 0.3s;
}
nav a:hover {
    color: var(--primary-color);
}

/* 语言切换按钮 */
.lang-btn {
    font-weight: bold;
    border: 1px solid var(--primary-color);
    padding: 4px 10px;
    border-radius: 4px;
    color: var(--primary-color) !important;
}
.lang-btn:hover {
    background: var(--primary-color);
    color: #fff !important;
}

/* 首页横幅 (Hero) */
.hero {
    height: 70vh;
    background: linear-gradient(rgba(0, 0, 0, 0.7), rgba(0, 0, 0, 0.7)), url('https://images.unsplash.com/photo-1558494949-ef010cbdcc31?q=80&w=2000&auto=format&fit=crop') no-repeat center center/cover;
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 0 20px;
}
.hero h2 {
    font-size: 3rem;
    margin-bottom: 1rem;
}
.hero p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}
.btn {
    display: inline-block;
    padding: 10px 30px;
    background: var(--secondary-color);
    color: #fff;
    text-decoration: none;
    border-radius: 5px;
    font-size: 1.1rem;
    transition: background 0.3s;
}
.btn:hover {
    background: var(--primary-color);
}

/* 网格布局 (核心业务) */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}
.card {
    background: #fff;
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s;
}
.card:hover {
    transform: translateY(-5px);
}
.card h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

/* 联系方式与页脚 */
.contact-info {
    margin-top: 2rem;
    font-size: 1.2rem;
}
footer {
    background: var(--dark-color);
    color: #fff;
    text-align: center;
    padding: 1.5rem 0;
}

/* 移动端适配 */
@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        height: auto;
        padding: 10px 0;
    }
    .logo-img {
        height: 60px;
        margin-bottom: 15px;
    }
    nav {
        flex-wrap: wrap;
        justify-content: center;
    }
    nav a {
        color: var(--header-text);
        margin: 5px 10px;
    }
    .hero h2 {
        font-size: 2rem;
    }
    .hero p {
        font-size: 1rem;
    }
    .card {
        padding: 1.5rem;
    }
}