/* ================================
   全局样式
   ================================ */
:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --light-bg: #f9fafb;
    --dark-text: #1f2937;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif, 'Microsoft YaHei';
    color: var(--dark-text);
    background-color: #fff;
}

/* ================================
   导航栏样式
   ================================ */
.navbar {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    top: 0;
    z-index: 1000;
}

.navbar-brand {
    font-size: 24px;
    color: #fff !important;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: transform 0.3s ease;
}

.navbar-brand:hover {
    transform: scale(1.05);
}

.navbar-nav .nav-link {
    color: #fff !important;
    font-weight: 500;
    margin: 0 10px;
    position: relative;
    transition: all 0.3s ease;
}

.navbar-nav .nav-link::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -5px;
    left: 0;
    background-color: #fff;
    transition: width 0.3s ease;
}

.navbar-nav .nav-link:hover::after {
    width: 100%;
}

/* 设置导航栏顶部距离 */
body {
    padding-top: 70px;
}

/* ================================
   轮播图样式
   ================================ */
.banner-carousel {
    height: 560px;
    margin-top: -70px;
    padding-top: 70px;
    margin-bottom: 30px;
}

.carousel-item {
    height: 560px;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.carousel-content {
    text-align: center;
    animation: slideInUp 0.8s ease;
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.carousel-control-prev,
.carousel-control-next {
    width: 50px;
    height: 50px;
    background-color: rgba(0, 0, 0, 0.3);
    border-radius: 50%;
    top: 50%;
    transform: translateY(-50%);
}

.carousel-indicators button {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.5);
    border: none;
    transition: all 0.3s ease;
}

.carousel-indicators button.active {
    background-color: #fff;
    width: 30px;
    border-radius: 10px;
}

/* ================================
   Section 标题样式
   ================================ */
.section-title {
    font-size: 36px;
    font-weight: bold;
    color: var(--dark-text);
    margin-bottom: 15px;
}

.title-underline {
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    margin: 0 auto;
    border-radius: 2px;
}

/* ================================
   特色介绍样式
   ================================ */
.features-section {
    background: #fff;
    padding: 60px 0;
    margin-top: 0;
}

.feature-card {
    text-align: center;
    padding: 30px 20px;
    border-radius: 15px;
    transition: all 0.3s ease;
    background: #fff;
    border: 1px solid #e5e7eb;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    border-color: var(--primary-color);
}

.feature-icon {
    font-size: 48px;
    color: var(--primary-color);
    margin-bottom: 20px;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px);
    }
    50% {
        transform: translateY(-10px);
    }
}

.feature-card h4 {
    font-size: 20px;
    font-weight: bold;
    margin-bottom: 15px;
    color: var(--dark-text);
}

.feature-card p {
    color: #6b7280;
    font-size: 14px;
    line-height: 1.6;
}

/* ================================
   课程卡片样式
   ================================ */
.courses-section {
    padding: 60px 0;
    background-color: var(--light-bg);
}

.course-card {
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    background: #fff;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.course-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.course-image {
    height: 150px;
    width: 100%;
    background: linear-gradient(135deg, #667eea, #764ba2);
}

.course-body {
    padding: 25px;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.course-body h5 {
    font-size: 18px;
    font-weight: bold;
    margin-bottom: 10px;
    color: var(--dark-text);
}

.course-price {
    font-size: 24px;
    color: var(--primary-color);
    font-weight: bold;
    margin-bottom: 10px;
}

.course-desc {
    color: #6b7280;
    font-size: 14px;
    margin-bottom: 15px;
    flex-grow: 1;
}

.course-stats {
    display: flex;
    justify-content: space-between;
    color: #9ca3af;
    font-size: 13px;
    margin-bottom: 15px;
}

.course-stats span {
    display: flex;
    align-items: center;
    gap: 5px;
}

.course-card .btn {
    margin-top: auto;
}

/* ================================
   成功案例样式
   ================================ */
.success-section {
    padding: 60px 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.05) 0%, rgba(118, 75, 162, 0.05) 100%);
}

.success-card {
    padding: 40px 20px;
    border-radius: 12px;
    background: #fff;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.success-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.12);
}

.success-card h3 {
    margin-bottom: 15px;
}

.success-card p {
    color: #6b7280;
    font-size: 16px;
    margin: 0;
}

/* ================================
   讲师预览样式
   ================================ */
.teachers-preview-section {
    padding: 60px 0;
    background-color: var(--light-bg);
}

.teacher-card {
    text-align: center;
    border-radius: 12px;
    overflow: hidden;
    background: #fff;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.teacher-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.teacher-image {
    height: 200px;
    background: linear-gradient(135deg, #667eea, #764ba2);
}

.teacher-info {
    padding: 25px;
}

.teacher-info h5 {
    font-size: 18px;
    font-weight: bold;
    margin-bottom: 8px;
    color: var(--dark-text);
}

.teacher-subject {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 15px;
}

.teacher-desc {
    color: #6b7280;
    font-size: 14px;
    line-height: 1.6;
}

/* ================================
   报名区域样式
   ================================ */
.registration-section {
    padding: 60px 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
}

.registration-box {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    padding: 50px 40px;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.2);
}

.registration-box h2 {
    font-size: 32px;
    font-weight: bold;
    color: var(--dark-text);
    margin-bottom: 20px;
}

.registration-box .lead {
    color: #6b7280;
    font-size: 16px;
}

.registration-box ul li {
    color: #6b7280;
}

.registration-box ul li i {
    margin-right: 10px;
    font-size: 14px;
}

.registration-form {
    background: #fff;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.registration-form .form-control,
.registration-form .form-select {
    border: 2px solid #e5e7eb;
    border-radius: 10px;
    padding: 12px 15px;
    font-size: 14px;
    transition: all 0.3s ease;
}

.registration-form .form-control:focus,
.registration-form .form-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.registration-form .btn {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border: none;
    font-weight: bold;
    font-size: 16px;
    padding: 12px;
    border-radius: 10px;
    transition: all 0.3s ease;
}

.registration-form .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

/* ================================
   页脚样式
   ================================ */
.footer {
    background: linear-gradient(135deg, #1f2937 0%, #111827 100%);
    color: #d1d5db;
}

.footer h5 {
    color: #fff;
    font-weight: bold;
    margin-bottom: 15px;
}

.footer a {
    color: #9ca3af;
    transition: color 0.3s ease;
}

.footer a:hover {
    color: var(--primary-color);
}

.footer p {
    margin-bottom: 10px;
    font-size: 14px;
}

.social-links {
    display: flex;
    gap: 15px;
}

.social-links a {
    width: 40px;
    height: 40px;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    transition: all 0.3s ease;
}

.social-links a:hover {
    background-color: var(--primary-color);
    transform: translateY(-3px);
}

.footer hr {
    border-color: rgba(255, 255, 255, 0.1);
}

/* ================================
   通用按钮样式
   ================================ */
.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border: none;
    font-weight: 600;
    transition: all 0.3s ease;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(102, 126, 234, 0.4);
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: #fff;
}

.btn-light {
    background-color: #fff;
    color: var(--primary-color);
    font-weight: 600;
    transition: all 0.3s ease;
}

.btn-light:hover {
    background-color: #f3f4f6;
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
}

/* ================================
   响应式设计
   ================================ */
@media (max-width: 768px) {
    .banner-carousel {
        height: 380px;
        margin-top: -56px;
        padding-top: 56px;
        margin-bottom: 20px;
    }

    .carousel-item {
        height: 380px;
    }

    .carousel-content h1 {
        font-size: 24px !important;
    }

    .carousel-content p {
        font-size: 14px;
    }

    .section-title {
        font-size: 28px;
    }

    .registration-box {
        padding: 30px 20px;
    }

    .registration-form {
        margin-top: 30px;
    }

    body {
        padding-top: 56px;
    }

    .navbar-brand {
        font-size: 20px;
    }

    .feature-card {
        padding: 20px;
    }

    .feature-icon {
        font-size: 36px;
    }

    .features-section {
        padding: 40px 0;
    }

    .courses-section {
        padding: 40px 0;
    }

    .success-section {
        padding: 40px 0;
    }

    .teachers-preview-section {
        padding: 40px 0;
    }

    .registration-section {
        padding: 40px 0;
    }

    .success-card {
        padding: 25px 15px;
    }

    .success-card h3 {
        font-size: 28px;
    }

    .course-card {
        margin-bottom: 20px;
    }
}

@media (max-width: 576px) {
    .banner-carousel {
        height: 300px;
        margin-top: -56px;
        padding-top: 56px;
        margin-bottom: 15px;
    }

    .carousel-item {
        height: 300px;
    }

    .carousel-content h1 {
        font-size: 20px !important;
    }

    .section-title {
        font-size: 24px;
    }

    .features-section {
        padding: 30px 0;
    }

    .courses-section {
        padding: 30px 0;
    }

    .success-section {
        padding: 30px 0;
    }

    .teachers-preview-section {
        padding: 30px 0;
    }

    .registration-section {
        padding: 30px 0;
    }

    .feature-icon {
        font-size: 28px;
    }

    .feature-card h4 {
        font-size: 16px;
    }

    .feature-card p {
        font-size: 12px;
    }

    .course-price {
        font-size: 20px;
    }

    .registration-box {
        padding: 20px 15px;
    }

    .registration-box h2 {
        font-size: 24px;
    }

    .registration-form {
        padding: 15px;
    }

    .footer {
        text-align: center;
    }

    .social-links {
        justify-content: center;
    }
}

/* ================================
   动画效果
   ================================ */
.fade-in {
    animation: fadeIn 0.6s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

/* 页面加载动画 */
@keyframes slideInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ================================
   其他页面共用样式
   ================================ */
.page-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: #fff;
    padding: 80px 0;
    text-align: center;
    margin-top: -70px;
    padding-top: 120px;
}

.page-header h1 {
    font-size: 40px;
    font-weight: bold;
    margin-bottom: 10px;
}

.page-header p {
    font-size: 16px;
    opacity: 0.9;
}

.breadcrumb {
    background-color: var(--light-bg);
    padding: 15px 0;
}

.breadcrumb a {
    color: var(--primary-color);
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

/* ================================
   讲师详情页样式
   ================================ */
.teacher-detail-card {
    text-align: center;
    border-radius: 15px;
    overflow: hidden;
    background: #fff;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.teacher-detail-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.15);
}

.teacher-image-lg {
    height: 180px;
    width: 100%;
    background: linear-gradient(135deg, #667eea, #764ba2);
}

.teacher-detail-info {
    padding: 30px 20px;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.teacher-detail-info h5 {
    font-size: 20px;
    font-weight: bold;
    margin-bottom: 8px;
    color: var(--dark-text);
}

.teacher-detail-info .teacher-subject {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 10px;
    font-size: 14px;
}

.teacher-credentials {
    color: #6b7280;
    font-size: 13px;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 5px;
}

.teacher-description {
    color: #6b7280;
    font-size: 13px;
    line-height: 1.6;
    margin-bottom: 20px;
    flex-grow: 1;
}

.teacher-stats {
    display: flex;
    justify-content: space-around;
    margin-bottom: 20px;
    padding: 15px 0;
    border-top: 1px solid #e5e7eb;
    border-bottom: 1px solid #e5e7eb;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 20px;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.stat-label {
    font-size: 12px;
    color: #9ca3af;
}

.teacher-social {
    display: flex;
    justify-content: center;
    gap: 10px;
}

.teacher-social a {
    width: 36px;
    height: 36px;
    background-color: var(--light-bg);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    transition: all 0.3s ease;
    font-size: 14px;
}

.teacher-social a:hover {
    background-color: var(--primary-color);
    color: #fff;
    transform: translateY(-3px);
}

/* ================================
   高亮卡片样式（讲师风采）
   ================================ */
.highlight-card {
    background: #fff;
    padding: 40px 30px;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    border-top: 4px solid var(--primary-color);
}

.highlight-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.highlight-icon {
    font-size: 48px;
    color: var(--primary-color);
    margin-bottom: 20px;
    display: inline-block;
    animation: float 3s ease-in-out infinite;
}

.highlight-card h5 {
    font-size: 20px;
    font-weight: bold;
    margin-bottom: 15px;
    color: var(--dark-text);
}

.highlight-card p {
    color: #6b7280;
    font-size: 14px;
    line-height: 1.6;
}

/* ================================
   响应式设计 - 讲师页面
   ================================ */
@media (max-width: 768px) {
    .teacher-detail-card {
        margin-bottom: 20px;
    }

    .teacher-detail-info {
        padding: 20px 15px;
    }

    .teacher-detail-info h5 {
        font-size: 18px;
    }

    .teacher-description {
        font-size: 12px;
    }

    .teacher-stats {
        padding: 10px 0;
    }

    .stat-number {
        font-size: 18px;
    }

    .stat-label {
        font-size: 11px;
    }

    .highlight-card {
        padding: 25px 20px;
    }

    .highlight-icon {
        font-size: 36px;
    }

    .highlight-card h5 {
        font-size: 18px;
    }

    .highlight-card p {
        font-size: 13px;
    }
}

@media (max-width: 576px) {
    .teacher-image-lg {
        height: 150px;
    }

    .teacher-detail-info {
        padding: 15px 10px;
    }

    .teacher-detail-info h5 {
        font-size: 16px;
    }

    .teacher-credentials {
        font-size: 12px;
    }

    .teacher-description {
        font-size: 11px;
        margin-bottom: 15px;
    }

    .teacher-stats {
        padding: 8px 0;
        margin-bottom: 15px;
    }

    .stat-number {
        font-size: 16px;
    }

    .stat-label {
        font-size: 10px;
    }

    .teacher-social {
        gap: 8px;
    }

    .teacher-social a {
        width: 32px;
        height: 32px;
        font-size: 12px;
    }

    .highlight-card {
        padding: 20px 15px;
    }

    .highlight-icon {
        font-size: 32px;
    }

    .highlight-card h5 {
        font-size: 16px;
        margin-bottom: 10px;
    }

    .highlight-card p {
        font-size: 12px;
    }
}

/* ================================
   关于页面样式
   ================================ */
.mission-card {
    background: #fff;
    padding: 40px 30px;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.mission-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.mission-icon {
    font-size: 48px;
    color: var(--primary-color);
    margin-bottom: 20px;
    display: inline-block;
}

.mission-card h4 {
    font-size: 22px;
    font-weight: bold;
    margin-bottom: 15px;
    color: var(--dark-text);
}

.mission-card p {
    color: #6b7280;
    font-size: 14px;
    line-height: 1.8;
}

.value-card {
    background: #fff;
    padding: 30px 25px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.value-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.value-icon {
    font-size: 40px;
    color: var(--primary-color);
    margin-bottom: 15px;
    display: inline-block;
}

.value-card h5 {
    font-size: 18px;
    font-weight: bold;
    margin-bottom: 10px;
    color: var(--dark-text);
}

.value-card p {
    color: #6b7280;
    font-size: 13px;
    line-height: 1.6;
}

.achievement-card {
    background: #fff;
    padding: 35px 25px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    border-left: 5px solid var(--primary-color);
}

.achievement-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.achievement-card h3 {
    font-size: 32px;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.achievement-card p {
    color: #6b7280;
    font-size: 14px;
    line-height: 1.6;
}

.reason-card {
    background: #fff;
    padding: 30px 25px;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    position: relative;
}

.reason-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.reason-number {
    font-size: 48px;
    color: var(--primary-color);
    font-weight: bold;
    opacity: 0.1;
    position: absolute;
    top: 15px;
    right: 20px;
}

.reason-card h5 {
    font-size: 18px;
    font-weight: bold;
    margin-bottom: 12px;
    color: var(--dark-text);
}

.reason-card p {
    color: #6b7280;
    font-size: 14px;
    line-height: 1.6;
}

/* ================================
   联系页面样式
   ================================ */
.contact-section {
    padding: 80px 0;
}

.contact-item {
    text-align: center;
    padding: 30px;
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.contact-item:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.contact-icon {
    font-size: 48px;
    color: var(--primary-color);
    margin-bottom: 20px;
    display: inline-block;
}

.contact-item h5 {
    font-size: 20px;
    font-weight: bold;
    margin-bottom: 15px;
    color: var(--dark-text);
}

.contact-item p {
    color: #6b7280;
    font-size: 16px;
    margin: 0;
}

.contact-form {
    background: #fff;
    padding: 40px 35px;
    border-radius: 15px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.contact-form h4 {
    font-size: 24px;
    font-weight: bold;
    margin-bottom: 30px;
    color: var(--dark-text);
}

.contact-form .form-group {
    margin-bottom: 25px;
}

.contact-form label {
    display: block;
    margin-bottom: 8px;
    color: var(--dark-text);
    font-weight: 500;
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    font-size: 14px;
    font-family: inherit;
    transition: all 0.3s ease;
}

.contact-form input:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.contact-form textarea {
    resize: vertical;
    min-height: 120px;
}

.contact-form button {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
}

.contact-form button:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(102, 126, 234, 0.3);
}

.message-box {
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 20px;
    display: none;
}

.message-box.success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
    display: block;
}

.message-box.error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
    display: block;
}

/* ================================
   响应式设计 - 关于和联系页面
   ================================ */
@media (max-width: 768px) {
    .mission-card {
        padding: 25px 20px;
    }

    .mission-icon {
        font-size: 36px;
    }

    .mission-card h4 {
        font-size: 20px;
    }

    .mission-card p {
        font-size: 13px;
    }

    .value-card {
        padding: 20px 15px;
    }

    .value-icon {
        font-size: 32px;
    }

    .value-card h5 {
        font-size: 16px;
    }

    .value-card p {
        font-size: 12px;
    }

    .achievement-card {
        padding: 25px 15px;
    }

    .achievement-card h3 {
        font-size: 28px;
    }

    .achievement-card p {
        font-size: 13px;
    }

    .reason-card {
        padding: 20px;
    }

    .reason-number {
        font-size: 36px;
        top: 10px;
        right: 15px;
    }

    .reason-card h5 {
        font-size: 16px;
    }

    .reason-card p {
        font-size: 13px;
    }

    .contact-item {
        padding: 20px;
        margin-bottom: 20px;
    }

    .contact-icon {
        font-size: 36px;
    }

    .contact-item h5 {
        font-size: 18px;
    }

    .contact-item p {
        font-size: 14px;
    }

    .contact-form {
        padding: 25px 20px;
    }

    .contact-form h4 {
        font-size: 20px;
        margin-bottom: 20px;
    }
}

@media (max-width: 576px) {
    .mission-card {
        padding: 20px 15px;
    }

    .mission-icon {
        font-size: 32px;
    }

    .mission-card h4 {
        font-size: 18px;
    }

    .mission-card p {
        font-size: 12px;
    }

    .value-icon {
        font-size: 28px;
    }

    .value-card h5 {
        font-size: 15px;
    }

    .achievement-card h3 {
        font-size: 24px;
    }

    .reason-number {
        font-size: 32px;
    }

    .reason-card h5 {
        font-size: 15px;
    }

    .contact-icon {
        font-size: 32px;
    }

    .contact-item h5 {
        font-size: 16px;
    }

    .contact-form {
        padding: 20px 15px;
    }

    .contact-form h4 {
        font-size: 18px;
    }

    .contact-form input,
    .contact-form textarea {
        padding: 10px 12px;
        font-size: 13px;
    }

    .contact-form button {
        padding: 12px;
        font-size: 14px;
    }
}