body {
    background-color: white;
    transition: background-color 0.5s;
  }
  
  .running-demo {
    display: flex;
    gap: 20px;
  }
  
  .running-demo .el {
    width: 50px;
    height: 50px;
    background-color: #3498db;
  }
  
  .running-demo .circle.el {
    border-radius: 50%;
  }
  
  .running-demo .triangle.el {
    width: 0;
    height: 0;
    border-left: 25px solid transparent;
    border-right: 25px solid transparent;
    border-bottom: 50px solid #e74c3c;
  }
  
  .running-log {
    margin-top: 20px;
  }