/* 变量定义 */
:root {
    --primary-color: #e74c3c;
    --secondary-color: #f39c12;
    --text-color: #333;
    --text-light: #666;
    --background-light: #f9f9f9;
    --background-dark: #2c3e50;
    --border-radius: 8px;
    --box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  }
  
  /* 全局样式 */
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  body {
    font-family: 'PingFang SC', 'Microsoft YaHei', sans-serif;
    color: var(--text-color);
    line-height: 1.6;
  }
  
  .container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
  }
  
  .section-title {
    font-size: 36px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 40px;
    position: relative;
  }
  
  .section-title:after {
    content: '';
    display: block;
    width: 80px;
    height: 4px;
    background: var(--primary-color);
    margin: 15px auto 0;
    border-radius: 2px;
  }
  
  /* 顶部导航 */
  .header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    z-index: 100;
    padding: 15px 0;
  }
  
  .header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
  }
  
  .header .logo img {
    height: 40px;
  }
  
  .header .nav {
    display: flex;
    gap: 25px;
  }
  
  .header .nav-link {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
  }
  
  .header .nav-link:hover {
    color: var(--primary-color);
  }
  
  .header .register-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 30px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s;
  }
  
  .header .register-btn:hover {
    background: #c0392b; /* darken primary color */
  }
  
  /* 主视觉区域 */
  .hero {
    padding: 160px 0 100px;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  }
  
  .hero .container {
    display: flex;
    align-items: center;
  }
  
  .hero .hero-content {
    flex: 1;
    padding-right: 40px;
  }
  
  .hero .hero-title {
    font-size: 48px;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 20px;
  }
  
  .hero .hero-title .highlight {
    color: var(--primary-color);
  }
  
  .hero .hero-subtitle {
    font-size: 24px;
    margin-bottom: 15px;
    color: var(--text-light);
  }
  
  .hero .hero-date {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 30px;
    color: var(--secondary-color);
  }
  
  .hero .hero-buttons {
    display: flex;
    gap: 15px;
  }
  
  .hero .hero-buttons button {
    padding: 12px 30px;
    border-radius: 30px;
    font-weight: 600;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s;
  }
  
  .hero .hero-buttons .primary-btn {
    background: var(--primary-color);
    color: white;
    border: none;
  }
  
  .hero .hero-buttons .primary-btn:hover {
    background: #c0392b; /* darken primary color */
    transform: translateY(-2px);
  }
  
  .hero .hero-buttons .secondary-btn {
    background: transparent;
    color: var(--text-color);
    border: 2px solid var(--text-color);
  }
  
  .hero .hero-buttons .secondary-btn:hover {
    background: var(--text-color);
    color: white;
    transform: translateY(-2px);
  }
  
  .hero .hero-image {
    flex: 1;
  }
  
  .hero .hero-image img {
    width: 100%;
    border-radius: 10px;
    box-shadow: var(--box-shadow);
  }
  
  /* 关于大湾区 */
  .about {
    padding: 100px 0;
    background: white;
  }
  
  .about .bay-area-map {
    max-width: 800px;
    margin: 0 auto 40px;
  }
  
  .about .bay-area-map .map-image {
    width: 100%;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
  }
  
  .about .about-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
  }
  
  .about .about-card {
    background: var(--background-light);
    border-radius: var(--border-radius);
    padding: 30px;
    box-shadow: var(--box-shadow);
    transition: transform 0.3s;
  }
  
  .about .about-card:hover {
    transform: translateY(-5px);
  }
  
  .about .about-card h3 {
    font-size: 20px;
    margin-bottom: 15px;
  }
  
  .about .about-card p {
    color: var(--text-light);
    font-size: 15px;
  }
  
  /* 大赛意义 */
  .purpose {
    padding: 100px 0;
    background: var(--background-light);
  }
  
  .purpose .purpose-images {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-bottom: 40px;
  }
  
  .purpose .purpose-image {
    width: 45%;
    max-width: 500px;
  }
  
  .purpose .purpose-image .tech-image {
    width: 100%;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
  }
  
  .purpose .purpose-intro {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 60px;
    font-size: 18px;
    color: var(--text-light);
  }
  
  .purpose .purpose-points {
    display: flex;
    flex-direction: column;
    gap: 40px;
  }
  
  .purpose .purpose-point {
    display: flex;
    gap: 30px;
  }
  
  .purpose .purpose-point .point-number {
    font-size: 64px;
    font-weight: 800;
    color: var(--primary-color);
    opacity: 0.2;
    line-height: 1;
  }
  
  .purpose .purpose-point .point-content {
    flex: 1;
  }
  
  .purpose .purpose-point .point-content h3 {
    font-size: 24px;
    margin-bottom: 15px;
    color: var(--primary-color);
  }
  
  .purpose .purpose-point .point-content p {
    color: var(--text-light);
    font-size: 16px;
  }
  
  /* 受助对象展示 */
  .beneficiaries {
    padding: 100px 0;
    background: white;
  }
  
  .beneficiaries .beneficiaries-banner {
    max-width: 900px;
    margin: 0 auto 40px;
  }
  
  .beneficiaries .beneficiaries-banner .banner-image {
    width: 100%;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
  }
  
  .beneficiaries .beneficiaries-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
  }
  
  .beneficiaries .beneficiary-card {
    background: var(--background-light);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--box-shadow);
    transition: transform 0.3s;
  }
  
  .beneficiaries .beneficiary-card:hover {
    transform: translateY(-5px);
  }
  
  .beneficiaries .beneficiary-card .beneficiary-image {
    width: 100%;
    height: 250px;
    object-fit: cover;
  }
  
  .beneficiaries .beneficiary-card .beneficiary-info {
    padding: 20px;
  }
  
  .beneficiaries .beneficiary-card .beneficiary-info h3 {
    font-size: 20px;
    margin-bottom: 10px;
    color: var(--primary-color);
  }
  
  .beneficiaries .beneficiary-card .beneficiary-info p {
    color: var(--text-light);
    font-size: 15px;
  }
  
  /* 数字公益理念 */
  .digital-charity {
    padding: 100px 0;
    background: var(--background-light);
  }
  
  .digital-charity .digital-charity-content {
    display: flex;
    align-items: center;
    gap: 40px;
  }
  
  .digital-charity .digital-charity-image {
    flex: 1;
  }
  
  .digital-charity .digital-charity-image .concept-image {
    width: 100%;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
  }
  
  .digital-charity .digital-charity-text {
    flex: 1;
  }
  
  .digital-charity .digital-charity-text h3 {
    font-size: 28px;
    margin-bottom: 20px;
    color: var(--primary-color);
  }
  
  .digital-charity .digital-charity-text p {
    margin-bottom: 15px;
    font-size: 16px;
    color: var(--text-light);
  }
  
  /* 公益项目展示 */
  .charity-projects {
    padding: 100px 0;
    background: white;
  }
  
  .charity-projects .charity-projects-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
  }
  
  .charity-projects .charity-project-card {
    background: var(--background-light);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--box-shadow);
    transition: transform 0.3s;
  }
  
  .charity-projects .charity-project-card:hover {
    transform: translateY(-5px);
  }
  
  .charity-projects .charity-project-card .project-image {
    width: 100%;
    height: 250px;
    object-fit: cover;
  }
  
  .charity-projects .charity-project-card .project-info {
    padding: 20px;
  }
  
  .charity-projects .charity-project-card .project-info h3 {
    font-size: 20px;
    margin-bottom: 10px;
    color: var(--primary-color);
  }
  
  .charity-projects .charity-project-card .project-info p {
    color: var(--text-light);
    font-size: 15px;
  }
  
  /* 赛事规则 */
  .rules {
    padding: 100px 0;
    background: white;
  }
  
  .rules .rules-intro {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 60px;
    font-size: 18px;
    color: var(--text-light);
  }
  
  .rules .rules-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
    max-width: 800px;
    margin: 0 auto;
  }
  
  .rules .rule-item {
    display: flex;
    align-items: flex-start;
    gap: 20px;
    background: var(--background-light);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
  }
  
  .rules .rule-item .rule-number {
    width: 40px;
    height: 40px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 18px;
    flex-shrink: 0;
  }
  
  .rules .rule-item p {
    margin: 0;
    font-size: 16px;
  }
  
  /* 赛事时间 */
  .timeline {
    padding: 100px 0;
    background: var(--background-light);
  }
  
  .timeline .timeline-container {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
  }
  
  .timeline .timeline-container:before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 50%;
    width: 4px;
    background: var(--primary-color);
    transform: translateX(-50%);
  }
  
  .timeline .timeline-item {
    display: flex;
    margin-bottom: 50px;
    position: relative;
  }
  
  .timeline .timeline-item:last-child {
    margin-bottom: 0;
  }
  
  .timeline .timeline-item:before {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    background: var(--primary-color);
    border-radius: 50%;
    left: 50%;
    top: 15px;
    transform: translateX(-50%);
    z-index: 1;
  }
  
  .timeline .timeline-date {
    width: 50%;
    text-align: right;
    padding-right: 40px;
  }
  
  .timeline .timeline-date .date-range {
    display: block;
    font-size: 18px;
    font-weight: 600;
    color: var(--primary-color);
  }
  
  .timeline .timeline-date .date-phase {
    display: block;
    font-size: 14px;
    color: var(--text-light);
    margin-top: 5px;
  }
  
  .timeline .timeline-content {
    width: 50%;
    padding-left: 40px;
  }
  
  .timeline .timeline-content h3 {
    font-size: 24px;
    margin-bottom: 10px;
  }
  
  .timeline .timeline-content p {
    color: var(--text-light);
  }
  
  /* 公益活动展示 */
  .charity-events {
    padding: 100px 0;
    background: var(--background-light);
  }
  
  .charity-events .charity-events-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
  }
  
  .charity-events .charity-event-card {
    background: white;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--box-shadow);
    transition: transform 0.3s;
  }
  
  .charity-events .charity-event-card:hover {
    transform: translateY(-5px);
  }
  
  .charity-events .charity-event-card .event-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
  }
  
  .charity-events .charity-event-card .event-info {
    padding: 20px;
  }
  
  .charity-events .charity-event-card .event-info h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: var(--primary-color);
  }
  
  .charity-events .charity-event-card .event-info p {
    color: var(--text-light);
    font-size: 14px;
  }
  
  /* 奖励设置 */
  .prizes {
    padding: 100px 0;
    background: white;
  }
  
  .prizes .prizes-container {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-top: 40px;
  }
  
  .prizes .prize-card {
    width: 300px;
    padding: 40px 30px;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--box-shadow);
    transition: transform 0.3s;
  }
  
  .prizes .prize-card:hover {
    transform: translateY(-10px);
  }
  
  .prizes .prize-card .prize-medal {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 36px;
    font-weight: 700;
    color: white;
  }
  
  .prizes .prize-card h3 {
    font-size: 18px;
    margin-bottom: 20px;
  }
  
  .prizes .prize-card .prize-amount {
    font-size: 32px;
    font-weight: 700;
    color: var(--primary-color);
  }
  
  .prizes .prize-first {
    background: linear-gradient(to bottom, #f9f9f9, #f5f5f5);
    border-top: 5px solid #FFD700;
  }
  
  .prizes .prize-first .prize-medal {
    background: #FFD700;
  }
  
  .prizes .prize-second {
    background: linear-gradient(to bottom, #f9f9f9, #f5f5f5);
    border-top: 5px solid #C0C0C0;
  }
  
  .prizes .prize-second .prize-medal {
    background: #C0C0C0;
  }
  
  .prizes .prize-third {
    background: linear-gradient(to bottom, #f9f9f9, #f5f5f5);
    border-top: 5px solid #CD7F32;
  }
  
  .prizes .prize-third .prize-medal {
    background: #CD7F32;
  }
  
  /* 参赛选手 */
  .participants {
    padding: 100px 0;
    background: var(--background-light);
  }
  
  .participants .participants-intro {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 60px;
    font-size: 18px;
    color: var(--text-light);
  }
  
  .participants .participants-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 20px;
  }
  
  .participants .participant-card {
    text-align: center;
  }
  
  .participants .participant-card .participant-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    overflow: hidden;
    margin: 0 auto 15px;
    background: var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 24px;
    font-weight: bold;
  }
  
  .participants .participant-card .participant-name {
    font-weight: 600;
  }
  
  /* 底部区域 */
  .footer {
    background: var(--background-dark);
    color: white;
    padding: 80px 0 30px;
  }
  
  .footer .footer-content {
    display: flex;
    justify-content: space-between;
    margin-bottom: 50px;
  }
  
  .footer .footer-logo img {
    height: 40px;
    margin-bottom: 15px;
  }
  
  .footer .footer-logo p {
    color: rgba(255, 255, 255, 0.7);
  }
  
  .footer .footer-links {
    display: flex;
    gap: 60px;
  }
  
  .footer .footer-links-column h4 {
    font-size: 18px;
    margin-bottom: 20px;
    position: relative;
  }
  
  .footer .footer-links-column h4:after {
    content: '';
    display: block;
    width: 30px;
    height: 3px;
    background: var(--primary-color);
    margin-top: 10px;
  }
  
  .footer .footer-links-column a {
    display: block;
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 10px;
    text-decoration: none;
    transition: color 0.3s;
  }
  
  .footer .footer-links-column a:hover {
    color: white;
  }
  
  .footer .footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 30px;
    text-align: center;
  }
  
  .footer .footer-bottom p {
    color: rgba(255, 255, 255, 0.5);
    font-size: 14px;
  }
  
  /* 响应式设计 */
  @media (max-width: 992px) {
    .hero .container {
      flex-direction: column;
      text-align: center;
    }
    
    .hero .hero-content {
      padding-right: 0;
      margin-bottom: 40px;
    }
    
    .hero .hero-buttons {
      justify-content: center;
    }
    
    .about .about-grid {
      grid-template-columns: repeat(2, 1fr);
    }
    
    .beneficiaries .beneficiaries-grid,
    .charity-projects .charity-projects-grid,
    .charity-events .charity-events-grid {
      grid-template-columns: repeat(2, 1fr);
    }
    
    .digital-charity .digital-charity-content {
      flex-direction: column;
    }
    
    .participants .participants-grid {
      grid-template-columns: repeat(3, 1fr);
    }
    
    .prizes .prizes-container {
      flex-direction: column;
      align-items: center;
    }
  }
  
  @media (max-width: 768px) {
    .header .nav {
      display: none;
    }
    
    .hero .hero-title {
      font-size: 36px;
    }
    
    .purpose .purpose-images {
      flex-direction: column;
      align-items: center;
    }
    
    .purpose .purpose-image {
      width: 100%;
    }
    
    .purpose .purpose-point {
      flex-direction: column;
      gap: 15px;
    }
    
    .timeline .timeline-container:before {
      left: 30px;
    }
    
    .timeline .timeline-item {
      flex-direction: column;
      margin-left: 50px;
    }
    
    .timeline .timeline-item:before {
      left: -35px;
    }
    
    .timeline .timeline-date {
      width: 100%;
      text-align: left;
      padding-right: 0;
      margin-bottom: 15px;
    }
    
    .timeline .timeline-content {
      width: 100%;
      padding-left: 0;
    }
    
    .footer .footer-content {
      flex-direction: column;
      gap: 40px;
    }
  }
  
  @media (max-width: 576px) {
    .section-title {
      font-size: 28px;
    }
    
    .about .about-grid,
    .beneficiaries .beneficiaries-grid,
    .charity-projects .charity-projects-grid,
    .charity-events .charity-events-grid {
      grid-template-columns: 1fr;
    }
    
    .hero .hero-buttons {
      flex-direction: column;
    }
    
    .participants .participants-grid {
      grid-template-columns: repeat(2, 1fr);
    }
    
    .footer .footer-links {
      flex-direction: column;
      gap: 30px;
    }
  }