/* CSS3 样式设计 */
body {
    margin: 0;
    font-family: 'Helvetica', sans-serif;
    background-color: #f9f9f9;
    color: #333;
    overflow-x: hidden;
}
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: linear-gradient(135deg, #0A2463, #1C3F95);
    color: #fff;
    padding: 1rem;
    z-index: 1000;
    box-shadow: 0px 2px 8px rgba(0, 0, 0, 0.1);
}
header nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}
header nav .logo {
    font-size: 1.5rem;
    font-weight: bold;
    text-transform: uppercase;
}
header nav ul {
    list-style: none;
    display: flex;
    gap: 1.5rem;
}
header nav ul li a {
    color: #fff;
    text-decoration: none;
    transition: color 0.3s ease;
}
header nav ul li a:hover {
    color: #FF9F1C;
}
.hero {
    height: 100vh;
    background: url('https://images.gptkong.com/demo/sample1.png'), linear-gradient(135deg, #0A2463, #E5E5E5);
    background-size: cover;
    background-position: center;
    display: flex;
    justify-content: center;
    align-items: center;
    color: #fff;
    text-align: center;
    position: relative;
}
.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 36, 99, 0.7);
}
.hero h1 {
    font-size: 3rem;
    font-weight: bold;
    z-index: 1;
    position: relative;
}
.hero p {
    font-size: 1.2rem;
    z-index: 1;
    position: relative;
}
.section {
    padding: 4rem 1rem;
    max-width: 1200px;
    margin: 0 auto;
    text-align: center;
}
.section h2 {
    font-size: 2rem;
    color: #0A2463;
    margin-bottom: 1.5rem;
}
.section p {
    line-height: 1.6;
    margin-bottom: 2rem;
}
.cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}
.card {
    background: #fff;
    border-radius: 10px;
    box-shadow: 0px 4px 10px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    overflow: hidden;
    position: relative;
}
.card img {
    width: 100%;
    height: auto;
    display: block;
}
.card .content {
    padding: 1rem;
}
.card:hover {
    transform: scale(1.05);
    box-shadow: 0px 10px 20px rgba(0, 0, 0, 0.2);
}
footer {
    background: #0A2463;
    color: #fff;
    padding: 2rem 1rem;
    text-align: center;
}
footer p {
    margin: 0;
}
@media (max-width: 768px) {
    header nav {
        flex-direction: column;
    }
    header nav ul {
        flex-direction: column;
        gap: 1rem;
    }
    .hero h1 {
        font-size: 2rem;
    }
    .section h2 {
        font-size: 1.5rem;
    }
}
@media (max-width: 480px) {
    .cards {
        grid-template-columns: 1fr;
    }
    .hero h1 {
        font-size: 1.5rem;
    }
    .hero p {
        font-size: 1rem;
    }
}