.container1 {
    position: relative;
    margin-top: 50px;
    width: 350px;
    height: 205px;
  }
  
  .overlay1 {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0);
    transition: background 0.5s ease;
  }
  
  .container1:hover .overlay1 {
    display: block;
    background: rgba(0, 0, 0, .3);
  }
  
  .img1 {
    position: absolute;
    left: 0;
  }
  
  .button1 {
    position: absolute;
    width: 10px;
    left:160;
    top: 80px;
    text-align: center;
    opacity: 0;
    transition: opacity .35s ease;
  }
  .a1{
      cursor: pointer;
  }
  .button1{
    width: 30px;
    padding: 5px;
    border-radius: 20px;;
    color: white;
    border: solid 2px white;
    z-index: 1;
  }
  
  .container1:hover .button1 {
    opacity: 1;
  }