/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* 头部样式 */
header {
    text-align: center;
    margin-bottom: 30px;
    background: rgba(255, 255, 255, 0.95);
    padding: 20px;
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
}

header h1 {
    color: #4a5568;
    font-size: 2.5rem;
    margin-bottom: 10px;
    font-weight: 700;
}

.subtitle {
    color: #718096;
    font-size: 1.1rem;
    font-style: italic;
}

/* 主要内容区域 */
main {
    flex: 1;
    background: rgba(255, 255, 255, 0.95);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
    margin-bottom: 20px;
}

/* 登录表单样式 */
.login-form {
    max-width: 500px;
    margin: 0 auto;
    text-align: center;
}

.login-form h2 {
    color: #4a5568;
    margin-bottom: 30px;
    font-size: 1.8rem;
}

.form-group {
    margin-bottom: 25px;
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: #4a5568;
    font-weight: 600;
    font-size: 1.1rem;
}

.form-input {
    width: 100%;
    padding: 15px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 1rem;
    transition: all 0.3s ease;
    background: #fff;
}

.form-input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 12px 30px;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s ease;
    margin: 5px;
    min-width: 120px;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.3);
}

.btn-secondary {
    background: #e2e8f0;
    color: #4a5568;
}

.btn-secondary:hover {
    background: #cbd5e0;
    transform: translateY(-2px);
}

.btn-success {
    background: linear-gradient(135deg, #48bb78 0%, #38a169 100%);
    color: white;
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(72, 187, 120, 0.3);
}

.btn-warning {
    background: linear-gradient(135deg, #ed8936 0%, #dd6b20 100%);
    color: white;
}

.btn-warning:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(237, 137, 54, 0.3);
}

/* 信息区域样式 */
.info-section {
    margin-top: 40px;
    padding: 25px;
    background: #f7fafc;
    border-radius: 10px;
    border-left: 4px solid #667eea;
}

.info-section h3 {
    color: #4a5568;
    margin-bottom: 15px;
    font-size: 1.3rem;
}

.info-section ul {
    list-style: none;
    padding-left: 0;
}

.info-section li {
    padding: 8px 0;
    color: #718096;
    position: relative;
    padding-left: 25px;
}

.info-section li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: #48bb78;
    font-weight: bold;
}

/* 课程网格样式 */
.courses-section h2 {
    color: #4a5568;
    margin-bottom: 30px;
    font-size: 1.8rem;
    text-align: center;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 25px;
    margin-bottom: 30px;
}

.course-card {
    background: #fff;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    border: 1px solid #e2e8f0;
    transition: all 0.3s ease;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.15);
}

.course-card h3 {
    color: #4a5568;
    margin-bottom: 20px;
    font-size: 1.4rem;
    text-align: center;
}

.course-info {
    margin-bottom: 25px;
}

.course-info p {
    margin-bottom: 10px;
    color: #718096;
    font-size: 1rem;
}

.course-info strong {
    color: #4a5568;
}

.course-actions {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

.course-actions form {
    flex: 1;
    min-width: 100px;
}

/* 结果页面样式 */
.result-section {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.result-success {
    background: linear-gradient(135deg, #48bb78 0%, #38a169 100%);
    color: white;
    padding: 30px;
    border-radius: 15px;
    margin-bottom: 30px;
}

.result-error {
    background: linear-gradient(135deg, #f56565 0%, #e53e3e 100%);
    color: white;
    padding: 30px;
    border-radius: 15px;
    margin-bottom: 30px;
}

.result-success h2,
.result-error h2 {
    font-size: 2rem;
    margin-bottom: 20px;
}

.result-message {
    background: rgba(255, 255, 255, 0.2);
    padding: 20px;
    border-radius: 10px;
    margin-bottom: 20px;
}

.course-details {
    margin-top: 20px;
    text-align: left;
    background: rgba(255, 255, 255, 0.1);
    padding: 15px;
    border-radius: 8px;
}

.course-details h3 {
    margin-bottom: 15px;
    font-size: 1.2rem;
}

.course-details p {
    margin-bottom: 8px;
}

/* 错误页面样式 */
.error-section {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.error-message {
    background: linear-gradient(135deg, #f56565 0%, #e53e3e 100%);
    color: white;
    padding: 30px;
    border-radius: 15px;
    margin-bottom: 30px;
}

.error-message h2 {
    font-size: 2rem;
    margin-bottom: 20px;
}

.error-details {
    background: rgba(255, 255, 255, 0.2);
    padding: 20px;
    border-radius: 10px;
}

/* 操作按钮区域 */
.action-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

.no-courses {
    text-align: center;
    padding: 40px;
    color: #718096;
    font-size: 1.2rem;
}

/* 页脚样式 */
footer {
    text-align: center;
    padding: 20px;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
}

footer p {
    color: #718096;
    font-size: 0.9rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    main {
        padding: 20px;
    }
    
    .courses-grid {
        grid-template-columns: 1fr;
    }
    
    .course-actions {
        flex-direction: column;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        margin: 5px 0;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 1.8rem;
    }
    
    .login-form h2,
    .courses-section h2 {
        font-size: 1.5rem;
    }
    
    .course-card {
        padding: 20px;
    }
}