/* 基础样式 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Microsoft YaHei", "微软雅黑", sans-serif;
}

body {
  line-height: 1.6;
  color: #333;
  background-color: #f8f9fa;
}

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.btn {
  display: inline-block;
  padding: 10px 20px;
  background-color: #2c6ecb;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  font-size: 16px;
  transition: background-color 0.3s;
}

.btn:hover {
  background-color: #1a56b3;
}

.btn-secondary {
  background-color: #6c757d;
}

.btn-secondary:hover {
  background-color: #5a6268;
}

.section {
  padding: 60px 0;
}

.section-title {
  text-align: center;
  margin-bottom: 40px;
  font-size: 32px;
  color: #333;
  position: relative;
}

.section-title::after {
  content: '';
  display: block;
  width: 80px;
  height: 3px;
  background-color: #2c6ecb;
  margin: 15px auto 0;
}

/* 头部样式 */
header {
  background-color: white;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 0;
}

.logo {
  display: flex;
  align-items: center;
  font-size: 24px;
  font-weight: bold;
  color: #2c6ecb;
}

.logo img {
  height: 40px;
  margin-right: 10px;
}

.nav-links {
  display: flex;
}

.nav-links li {
  margin-left: 30px;
}

.nav-links a {
  font-weight: 500;
  transition: color 0.3s;
}

.nav-links a:hover {
  color: #2c6ecb;
}

.mobile-menu-btn {
  display: none;
  font-size: 24px;
  cursor: pointer;
}

/* 英雄区域 */
.hero {
  background: linear-gradient(rgba(44, 110, 203, 0.9), rgba(44, 110, 203, 0.8)), url('https://picsum.photos/id/0/1920/1080') center/cover no-repeat;
  color: white;
  padding: 100px 0;
  text-align: center;
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 48px;
  margin-bottom: 20px;
}

.hero p {
  font-size: 20px;
  margin-bottom: 30px;
  opacity: 0.9;
}

.hero-buttons {
  display: flex;
  justify-content: center;
  gap: 20px;
}

/* 功能特点 */
.features {
  background-color: white;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
}

.feature-card {
  background-color: #f8f9fa;
  padding: 30px;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
  transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.feature-icon {
  font-size: 40px;
  color: #2c6ecb;
  margin-bottom: 20px;
}

.feature-card h3 {
  font-size: 20px;
  margin-bottom: 15px;
}

/* 练习类型 */
.practice-types {
  background-color: #f1f3f5;
}

.types-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 25px;
}

.type-card {
  background-color: white;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  transition: transform 0.3s;
}

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

.type-img {
  height: 180px;
  overflow: hidden;
}

.type-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s;
}

.type-card:hover .type-img img {
  transform: scale(1.05);
}

.type-info {
  padding: 20px;
}

.type-info h3 {
  margin-bottom: 10px;
}

.type-info p {
  color: #666;
  margin-bottom: 15px;
}

/* 统计数据 */
.stats {
  background-color: #2c6ecb;
  color: white;
  text-align: center;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 30px;
}

.stat-item {
  padding: 20px;
}

.stat-number {
  font-size: 40px;
  font-weight: bold;
  margin-bottom: 10px;
}

.stat-label {
  font-size: 18px;
  opacity: 0.9;
}

/* 用户评价 */
.testimonials {
  background-color: white;
}

.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
}

.testimonial-card {
  background-color: #f8f9fa;
  padding: 30px;
  border-radius: 8px;
  position: relative;
}

.testimonial-text {
  font-style: italic;
  margin-bottom: 20px;
  position: relative;
}

.testimonial-text::before {
  content: '"';
  font-size: 50px;
  color: #2c6ecb;
  opacity: 0.2;
  position: absolute;
  top: -20px;
  left: -10px;
}

.testimonial-author {
  display: flex;
  align-items: center;
}

.author-avatar {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  margin-right: 15px;
  overflow: hidden;
}

.author-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.author-info h4 {
  font-weight: bold;
}

.author-info p {
  color: #666;
  font-size: 14px;
}

/* 下载区域 */
.download {
  background-color: #f1f3f5;
  text-align: center;
}

.download-content {
  max-width: 700px;
  margin: 0 auto;
}

.download p {
  font-size: 18px;
  margin-bottom: 30px;
}

.download-platforms {
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
}

.platform-btn {
  display: flex;
  align-items: center;
  background-color: white;
  color: #333;
  padding: 12px 20px;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s;
}

.platform-btn:hover {
  transform: translateY(-3px);
}

.platform-icon {
  font-size: 24px;
  margin-right: 10px;
}

/* 页脚 */
footer {
  background-color: #343a40;
  color: white;
  padding: 60px 0 20px;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 40px;
  margin-bottom: 40px;
}

.footer-column h3 {
  font-size: 18px;
  margin-bottom: 20px;
  position: relative;
  padding-bottom: 10px;
}

.footer-column h3::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 40px;
  height: 2px;
  background-color: #2c6ecb;
}

.footer-column ul li {
  margin-bottom: 10px;
}

.footer-column a {
  color: #ced4da;
  transition: color 0.3s;
}

.footer-column a:hover {
  color: white;
}

.social-links {
  display: flex;
  gap: 15px;
  margin-top: 20px;
}

.social-icon {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background-color: #495057;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color 0.3s;
}

.social-icon:hover {
  background-color: #2c6ecb;
}

.copyright {
  text-align: center;
  padding-top: 20px;
  border-top: 1px solid #495057;
  color: #ced4da;
  font-size: 14px;
}

/* 响应式设计 */
@media (max-width: 992px) {
  .hero h1 {
    font-size: 36px;
  }

  .hero p {
    font-size: 18px;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 70px;
    left: 0;
    right: 0;
    background-color: white;
    flex-direction: column;
    padding: 20px;
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.1);
  }

  .nav-links.active {
    display: flex;
  }

  .nav-links li {
    margin: 10px 0;
  }

  .mobile-menu-btn {
    display: block;
  }

  .hero {
    padding: 80px 0;
  }

  .hero h1 {
    font-size: 32px;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .section {
    padding: 40px 0;
  }

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

@media (max-width: 576px) {
  .hero h1 {
    font-size: 28px;
  }

  .hero p {
    font-size: 16px;
  }

  .stats-grid {
    grid-template-columns: 1fr 1fr;
  }

  .footer-content {
    grid-template-columns: 1fr;
  }
}