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


/* Body & Page Background */

body {
    display: flex;
    font-family: 'Arial', sans-serif;
    background-color: #f5f5f5;
    flex-direction: column;
    min-height: 100vh;
    margin: 0;
}
main {
    flex: 1;
}
footer {
    background-color: #f8f9fa;
    text-align: center;
    padding: 10px 0;
}
/* Header styles */
header {
    background-color: #2575fc;
    padding: 20px;
    color: white;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.site-name h1 {
    font-size: 24px;
}

.nav ul {
    list-style-type: none;
    display: flex;
    gap: 20px;
}

.nav ul li {
    display: inline;
}

.nav ul li a {
    color: white;
    text-decoration: none;
    font-size: 16px;
}

.user-avatar img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
}

/* Main content styles */
main {
    padding: 20px;
}

.course-selection h2 {
    font-size: 28px;
    margin-bottom: 20px;
}

.course-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.course-card {
    background-color: white;
    display: flex;
    flex-direction: column;
    border-radius: 8px;
    width: 300px;
    height: 400px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    transition: transform 0.3s ease;
    margin: 0px;
}

.select-button {
    display: block;
    width: 100%;
    padding: 10px;
    background-color: #2575fc;
    color: white;
    border: none;
    cursor: pointer;
    font-size: 16px;
    margin-top: auto; /* 将按钮推到父元素的底部 */
}
.course-card:hover {
    transform: translateY(-10px); /* 提升效果 */
}
.course-card img {
    width: 100%;
    height: 261px;
    object-fit: cover;
}

.course-card h3 {
    padding: 15px;
    font-size: 20px;
    color: #2575fc;
}

.course-card p {
    padding: 0 15px;
    font-size: 14px;
    color: #555;
}


.select-button:hover {
    background-color: #113c86;
}

.selected-button {
    display: block;
    width: 100%;
    padding: 10px;
    background-color: #8a8b8c;
    color: white;
    border: none;
    cursor: pointer;
    font-size: 16px;
    cursor: not-allowed;
    margin-top: auto; /* 将按钮推到父元素的底部 */
}

/* Footer styles */
footer {
    background-color: #333;
    color: white;
    text-align: center;
    padding: 10px;
    margin-top: 20px;
}