* { margin: 0; padding: 0; box-sizing: border-box;
     font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;}

 body {background-color: #f5f7fa; color: #333; line-height: 1.6;}

 /* header部分 */
 header {background: linear-gradient(135deg, #2c3e50, #4a6491); color: white; padding: 2rem 0;  
    text-align: center; box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);}
 .header-content { max-width: 1200px; margin: 0 auto; padding: 0 20px;}
 .header-content .hdTitle { font-size: 2.5rem; margin-bottom: 0.5rem; }
 .header-content .subTitle { font-size: 1.2rem; opacity: 0.9; margin-bottom: 1rem;
}

 /* 导航栏 */
 .nav { background-color: white; box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);}
 .nav-container { max-width: 1200px; margin: 0 auto; display: flex; justify-content: center;}
 .nav-item { padding: 1rem 1.5rem; color: #2c3e50; text-decoration: none; font-size: 18px; 
    font-weight: 500; transition: all 0.3s ease;}
 .nav-item:hover { background-color: #f0f4f8; color: #3498db;}

/* 主体部分 */
  main { max-width: 1200px; margin: 2rem auto; padding: 0 20px;}
 .mainSec { margin: 2rem 0;}
 .mainSec .secTitle {font-size: 1.6rem; color: #2c3e50; margin-bottom: 1.5rem; padding-bottom: 0.5rem; border-bottom: 2px solid #3498db;}
 .mainSec p{ text-align: justify; font-size: 16px; line-height: 1.6rem;}

 .experiments-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 1.5rem;  text-align:center;}
 
 .experiment-card { background-color: white; border-radius: 8px; overflow: hidden; box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
     transition: transform 0.3s ease, box-shadow 0.3s ease;}
 .experiment-card:hover { transform: translateY(-5px); box-shadow: 0 8px 16px rgba(0, 0, 0, 0.12);}
 .card-content { padding: 1.5rem;}
 .experiment-card h3 { font-size: 1.2rem; color: #2c3e50; margin-bottom: 0.8rem;}
 .experiment-card p { color: #666; margin-bottom: 1.5rem; font-size: 0.95rem;}
 .experiment-btn { display: block; background-color: #3498db; color: white; padding: 0.6rem 1.2rem; border-radius: 4px;
     text-decoration: none; font-weight: 500; transition: background-color 0.3s ease; /* 靠右对齐 */ float: right; margin-bottom: 1rem;}
 .experiment-btn:hover { background-color: #2980b9;}

 .bigButtonLink {display: none;  width: 150px; height: 100px; margin:auto;  background-color: white; border-radius: 8px; overflow: hidden; }
 .bigButton {background-color: #ADD8E6; border-radius: 8px; overflow: hidden; box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
     transition: transform 0.3s ease, box-shadow 0.3s ease; width: 150px; height: 100px; display: inline-block; margin: 0;  text-align: left;}
 .Button-content { padding: 1.5rem;}
 .bigButton h3 { font-size: 1.2rem; color: #2c3e50; margin-bottom: 0.8rem;}

  
 /* 底部区域 */
 .footer { background-color: #2c3e50; color: white; text-align: center; padding: 1rem 0; margin-top: 2rem;}
 .footer br{display: none;}

 @media (max-width: 768px) {


     /* header部分 */
  .header-content { padding: 0 10px;}
   .header-content .hdTitle { font-size: 1.8rem; margin-bottom: 0.5rem; }
  .header-content .subTitle { font-size: 1rem; opacity: 1; margin-bottom: 0;}

 /* 导航栏 */
 .nav { display: none;}

  /* 主体部分 */
  main { padding: 0 28px;}
 .mainSec .secTitle { font-size: 1.4rem; }
 .experiments-grid {grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); margin: 0; padding: 0;}
 .experiment-card { display: none;}
 .bigButtonLink {display: inline-block;  }
 .Button-content { padding: 1rem;}
 .bigButton h3 { font-size: 1rem;}

/* 底部区域 */
  .footer br{display: block;}
  .footer .shuxian{display: none;}


 }