/* 全局样式 */
:root {
    --primary-color: #2196F3;
    --secondary-color: #1976D2;
    --text-color: #333;
    --light-bg: #f5f5f5;
    --white: #ffffff;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
}

/* 导航栏样式 */
header {
    background-color: var(--white);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo-img {
    height: 40px;
    width: auto;
}

.logo span {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
}

nav a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.3s;
}

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

/* 主要内容区域 */
main {
    margin-top: 80px;
    padding: 2rem 1rem;
}

.content-section {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 1rem;
}

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

h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--primary-color);
}

/* 产品特点卡片 */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.project-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: transform 0.3s;
}

.project-card:hover {
    transform: translateY(-5px);
}

.project-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

/* 下载区域 */
.download-qr {
    text-align: center;
    margin: 2rem 0;
}

.qr-code {
    max-width: 200px;
    height: auto;
}

.download-links {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.download-btn {
    min-width: 180px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
}

/* 联系表单 */
.contact-form {
    max-width: 600px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

input, textarea {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
}

.btn {
    background-color: var(--primary-color);
    color: var(--white);
    padding: 0.8rem 2rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s;
}

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

/* 页脚 */
#footer {
    background-color: var(--light-bg);
    text-align: center;
    padding: 1rem;
    margin-top: 2rem;
}

#footer a {
    color: var(--text-color);
    text-decoration: none;
}

/* 响应式设计 */
@media (max-width: 768px) {
    nav {
        flex-direction: column;
        gap: 1rem;
    }

    nav ul {
        flex-direction: row;
        text-align: center;
        gap: 1rem;
        flex-wrap: wrap;
        justify-content: center;
    }

    nav ul li {
        margin: 0;
    }

    .projects-grid {
        grid-template-columns: 1fr;
    }

    h2 {
        font-size: 2rem;
    }

    .download-links {
        flex-direction: column;
        align-items: center;
    }
    
    .download-btn {
        width: 100%;
        max-width: 300px;
    }
}