@font-face {
  font-family: "OPPOSans-Regular";
  src: url("fonts/OPPOSans-Regular.woff2") format("woff2"),
       url("fonts/OPPOSans-Regular.woff") format("woff");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}

:root {
  --primary-color: #0363ef;
  --text-color: #2d2d2d;
  --muted-color: #6f6f6f;
  --bg-light: #f9f9f9;
  --border-color: #6f6f6f;
  --card-bg: #f4f4f4;
  --radius: 8px;
  --spacing: 20px;
  --max-width: 1200px;
}

/* 全局基础样式 */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "OPPOSans-Regular", Helvetica, sans-serif;
  color: var(--text-color);
  line-height: 1.6;
  background-color: #fff;
}

h1, h2, h3, h4, h5, h6 {
  font-family: "OPPOSans-Medium", Helvetica, sans-serif;
}

img {
  max-width: 100%;
  display: block;
}

/* 容器 */
.container {
  max-width: var(--max-width);
  margin: auto;
  padding: 1rem;
}

/* 通用卡片样式 */
.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: var(--spacing);
}

/* 导航栏 */
.navbar {
  background: #fff;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
  position: sticky;
  top: 0;
  z-index: 2000;
}

.nav-container {
  margin: auto;
  padding: 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  height: 50px;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  font-weight: 500;
  color: var(--text-color);
  text-decoration: none;
  transition: color 0.3s;
}

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

.nav-links a.active {
  color: var(--primary-color);
  font-weight: bold;    
  pointer-events: none; 
  border-bottom: 2px solid var(--primary-color);
  padding-bottom: 2px;
}

/* Hero Section */
.hero-section {
    padding: 80px 0 40px;
}

.hero-title {
    font-weight: 900;
    font-size: 36px;
    margin-bottom: 20px;
}

.hero-subtitle {
    color: rgba(111, 111, 111, 1);
    font-weight: 700;
    font-size: 24px;
}

/* Section Styles */
.section-title {
    font-weight: 900;
    font-size: 24px;
    margin-bottom: 30px;
    border-bottom: 1.5px solid #ccc;
    padding-bottom: 0.5rem; 
}

.activities-section,
.teacher-training-section {
    padding: 40px 0;
}

/* Grid Layouts */
.activities-grid,
.training-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  row-gap: 12px;
  column-gap: 12px;
}

.training-grid .big-card {
  grid-column: 1 / -1;
  display: grid;
}

/* Card Styles */
.activity-card, .training-card {
   position: relative;
   border-radius: 8px; 
   overflow: hidden; 
}

.card-image {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 8px;
  object-fit: cover;
}

/* 页脚 */
.footer {
  background: #f1f1f1;
  padding: 2rem 0;
  margin-top: 4rem;
  --max-width: 1200px;
  font-size: 14px;
  color: #707070;
  line-height: 2;
}
.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 0;
}

.footer-images {
  display: flex;
  gap: 1rem;          
  align-items: center;  
}

.footer-logo {
  height: 60px;
  margin-top: 0.5rem;  
}

.qrcode {
  width: 60px;
  margin-top: 0.5rem;  
  margin-left: 0;      
}

/* 响应式 */
@media (max-width: 768px) {
  .nav-links {
    flex-direction: column;
    gap: 0.7rem;
  }
  .hero {
    height: 250px;
  }
  .hero h1 {
    font-size: 1.5rem;
  }
}

/* 响应式：在小屏下改为上下结构 */
@media (max-width: 1024px) {
  .overlap-group {
    grid-template-columns: 1fr; /* 改为上下结构 */
    text-align: center;
  }

  .info {
    text-align: center;
  }

  .buttons {
    justify-content: center;
  }
}