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

body {
    font-family: 'PingFang SC', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
}

header {
    background-color: #fff;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
}

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

nav ul li {
    margin-left: 2rem;
}

nav ul li a {
    text-decoration: none;
    color: #333;
}

main {
    margin-top: 60px;
    padding: 2rem 5%;
}

section {
    margin: 4rem 0;
}

.product-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.product-card {
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    background: white;
    transition: transform 0.3s ease;
}

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

.product-icon {
    text-align: center;
    margin-bottom: 1.5rem;
}

.product-icon img {
    width: 80px;
    height: 80px;
    border-radius: 16px;
}

.product-features {
    margin: 1.5rem 0;
}

.product-features ul {
    list-style: none;
    padding: 0;
}

.product-features li {
    margin: 0.5rem 0;
    font-size: 0.95rem;
    color: #444;
}

.product-description {
    color: #666;
    font-size: 0.9rem;
    line-height: 1.6;
    margin: 1rem 0;
}

.product-actions {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.download-btn {
    flex: 1;
    text-align: center;
    padding: 0.8rem 1.2rem;
    border-radius: 6px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.download-btn.primary {
    background-color: #007bff;
    color: white;
}

.download-btn.secondary {
    background-color: #f8f9fa;
    color: #007bff;
    border: 1px solid #007bff;
}

.download-btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

footer {
    text-align: center;
    padding: 2rem;
    background-color: #f8f9fa;
}

@media (max-width: 768px) {
    nav {
        flex-direction: column;
        padding: 1rem;
    }

    nav ul {
        margin-top: 1rem;
    }

    nav ul li {
        margin-left: 1rem;
    }
}