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

body {
    font-family: 'Microsoft YaHei', sans-serif;
    background-color: #f5f5f5;
    color: #333;
}

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

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    color: #2c3e50;
    font-size: 2.5em;
    margin: 20px 0;
}

.course-cards {
    display: flex;
    justify-content: space-between;
    gap: 20px;
    margin-bottom: 40px;
}

.course-card {
    flex: 1;
    background: white;
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
    cursor: pointer;
}

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

.course-card h2 {
    color: #2c3e50;
    margin-bottom: 15px;
}

.course-image {
    width: 100%;
    max-width: 200px;
    height: auto;
    margin-bottom: 15px;
}

.price {
    font-size: 1.5em;
    color: #e74c3c;
    margin: 15px 0;
}

.view-details-btn {
    background-color: #3498db;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

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

.course-details {
    background: white;
    border-radius: 10px;
    padding: 30px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.course-content {
    display: none;
}

.course-content.active {
    display: block;
}

.course-info {
    margin: 20px 0;
}

.course-info h3 {
    color: #2c3e50;
    margin: 20px 0 10px;
}

.course-info ul {
    list-style-type: none;
    padding-left: 20px;
}

.course-info ul li {
    margin: 10px 0;
    position: relative;
}

.course-info ul li:before {
    content: "•";
    color: #3498db;
    font-weight: bold;
    position: absolute;
    left: -15px;
}

.buy-btn {
    background-color: #e74c3c;
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 5px;
    font-size: 1.1em;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.buy-btn:hover {
    background-color: #c0392b;
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
}

.modal-content {
    background-color: white;
    margin: 15% auto;
    padding: 20px;
    width: 80%;
    max-width: 500px;
    border-radius: 10px;
    text-align: center;
}

.close {
    color: #aaa;
    float: right;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
}

.close:hover {
    color: black;
}

.qr-code {
    margin: 20px 0;
}

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

@media (max-width: 768px) {
    .course-cards {
        flex-direction: column;
    }
    
    .course-card {
        margin-bottom: 20px;
    }
}