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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: #f5f5f5;
    min-height: 100vh;
}

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

/* 轮播图样式 */
.carousel {
    position: relative;
    width: 100%;
    max-width: 800px;
    margin: 0 auto 30px;
    overflow: hidden;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

.carousel-inner {
    display: flex;
    transition: transform 0.5s ease-in-out;
}

.carousel-item {
    min-width: 100%;
    height: 400px;
}

.carousel-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.carousel-control {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(0,0,0,0.5);
    color: white;
    border: none;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 20px;
    z-index: 10;
}

.carousel-control.prev {
    left: 10px;
}

.carousel-control.next {
    right: 10px;
}

.carousel-indicators {
    position: absolute;
    bottom: 15px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 10px;
}

.carousel-indicator {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: rgba(255,255,255,0.5);
    cursor: pointer;
    border: none;
}

.carousel-indicator.active {
    background: white;
}

/* 按钮区域 */
.buttons-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 40px;
}

.button-item {
    background: white;
    padding: 30px;
    border-radius: 12px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.button-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
}

.button-item img {
    width: 60px;
    height: 60px;
    margin-bottom: 15px;
    object-fit: contain;
}

.button-item span {
    font-size: 16px;
    font-weight: 600;
    color: #333;
}

/* 课程区域 */
.courses-section h2 {
    text-align: center;
    margin-bottom: 30px;
    color: #333;
    font-size: 28px;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 25px;
}

.course-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
}

.course-card img {
    width: 100%;
    height: 180px;
    object-fit: cover;
}

.course-card-content {
    padding: 20px;
}

.course-card h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: #333;
}

.course-card p {
    color: #666;
    font-size: 14px;
    line-height: 1.5;
}

/* 弹窗样式 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.6);
    z-index: 1000;
    justify-content: center;
    align-items: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: white;
    padding: 40px;
    border-radius: 12px;
    max-width: 400px;
    width: 90%;
}

.modal-content h2 {
    margin-bottom: 20px;
    text-align: center;
    color: #333;
}

.modal-content input {
    width: 100%;
    padding: 15px;
    margin-bottom: 20px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 16px;
}

.modal-content button {
    width: 100%;
    padding: 15px;
    background: #007bff;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.3s;
}

.modal-content button:hover {
    background: #0056b3;
}

/* 聊天页面样式 */
.chat-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    background: #f5f5f5;
}

.chat-header {
    background: white;
    padding: 15px 20px;
    border-bottom: 1px solid #e0e0e0;
    display: flex;
    align-items: center;
    gap: 15px;
}

.chat-header a {
    color: #333;
    text-decoration: none;
    font-size: 24px;
}

.chat-header h1 {
    font-size: 18px;
    color: #333;
}

.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
}

.message {
    margin-bottom: 20px;
    display: flex;
    gap: 10px;
}

.message.admin {
    flex-direction: row;
}

.message-content {
    background: white;
    padding: 12px 16px;
    border-radius: 12px;
    max-width: 70%;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.message.admin .message-content {
    background: #007bff;
    color: white;
}

.message-text {
    word-wrap: break-word;
}

.message-image, .message-video, .message-audio {
    max-width: 100%;
    border-radius: 8px;
}

.message-time {
    font-size: 12px;
    color: #999;
    margin-top: 5px;
}

/* 管理员后台样式 */
.admin-container {
    display: flex;
    min-height: 100vh;
}

.admin-sidebar {
    width: 250px;
    background: #2c3e50;
    color: white;
    padding: 20px 0;
}

.admin-sidebar h2 {
    padding: 0 20px 20px;
    border-bottom: 1px solid #34495e;
}

.admin-sidebar nav {
    padding: 20px 0;
}

.admin-sidebar nav a {
    display: block;
    padding: 15px 20px;
    color: #ecf0f1;
    text-decoration: none;
    transition: background 0.3s;
}

.admin-sidebar nav a:hover,
.admin-sidebar nav a.active {
    background: #34495e;
}

.admin-main {
    flex: 1;
    padding: 30px;
    overflow-y: auto;
}

.admin-section {
    display: none;
}

.admin-section.active {
    display: block;
}

.admin-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

.admin-header h2 {
    color: #333;
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s;
}

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

.btn-primary:hover {
    background: #0056b3;
}

.btn-danger {
    background: #dc3545;
    color: white;
}

.btn-danger:hover {
    background: #c82333;
}

.btn-sm {
    padding: 5px 10px;
    font-size: 12px;
}

.table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.table th,
.table td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #eee;
}

.table th {
    background: #f8f9fa;
    font-weight: 600;
    color: #333;
}

.table img {
    width: 60px;
    height: 40px;
    object-fit: cover;
    border-radius: 4px;
}

.actions {
    display: flex;
    gap: 10px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #333;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 14px;
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.login-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.login-box {
    background: white;
    padding: 40px;
    border-radius: 12px;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
}

.login-box h2 {
    text-align: center;
    margin-bottom: 30px;
    color: #333;
}

/* 聊天输入区域（管理员） */
.chat-input-area {
    background: white;
    padding: 15px 20px;
    border-top: 1px solid #e0e0e0;
    display: flex;
    gap: 10px;
    align-items: flex-end;
}

.chat-input-area textarea {
    flex: 1;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 8px;
    resize: none;
    font-size: 14px;
    min-height: 50px;
    max-height: 150px;
}

.chat-input-area .input-tools {
    display: flex;
    gap: 10px;
}

.chat-input-area .input-tools button {
    padding: 12px 20px;
    background: #007bff;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.3s;
}

.chat-input-area .input-tools button:hover {
    background: #0056b3;
}

.file-input-wrapper {
    position: relative;
    overflow: hidden;
}

.file-input-wrapper input {
    position: absolute;
    opacity: 0;
    width: 100%;
    height: 100%;
    cursor: pointer;
}

.message-delete {
    margin-left: 10px;
    cursor: pointer;
    color: #dc3545;
    opacity: 0.7;
    transition: opacity 0.3s;
}

.message-delete:hover {
    opacity: 1;
}