style.css

:root {
    --color:lightgray;
    --border-radius:10px;
  }
  
  body {
    background:#efefef;
    padding:0;
    margin:0;
    box-sizing:border-box;
  }
  
  #puz, #puzz {
    position:absolute;
    border-radius:var(--border-radius) 0 var(--border-radius) 0;    
    user-select:none;
  }
  #puz {
    width:300px;
    height:300px;
    position:absolute;
    top:50%;
    left:50%;
    transform:translate(-50%,-50%);
    border:3px dashed lightgray;
    overflow:hidden;
  }
  #puzz {
    left:0;
    top:0;
    border:0;
  }
  
  #puz i {
    float:left;
    width:100px;
    height:100px;
    outline:1px dashed lightgray;
  }
  
  #puzz i {
    position:absolute;
    width:100px;
    height:100px;
    background:var(--color);
    background-image:var(--image);
    background-size:300px 300px;
    cursor:move;
    box-shadow:0 0 10px rgba(0,0,0,.25);
  }
  
  .first {
    border-top-left-radius:var(--border-radius);
    background-position:left top !important;
  }
  .secon {
    background-position:center top !important;
  }
  .third {
  /*   border-top-right-radius:var(--border-radius); */
    background-position:right top !important;
  }
  .fourt {
    background-position:left center !important;
  }
  .fifth {
    background-position:center center !important;
  }
  .sixth {  
    background-position:right center !important;
  }
  .seven {
  /*   border-bottom-left-radius:var(--border-radius); */
    background-position:left bottom !important;
  }
  .eight {
    background-position:center bottom !important;
  }
  .ninth {
    border-bottom-right-radius:var(--border-radius);
    background-position:right bottom !important;
  }
  
  .clicked {
    box-shadow:0 0 0 4px gray !important;
  }
  
  .dropped {
    background:var(--color);
    background-image:var(--image);
    background-size:300px 300px;
  }
  .done {
    opacity:0;
    pointer-events:none;
  }
  
  .allDone {
    animation:allDone 1s linear forwards;
    border:3px solid lightgray !important;
  }
  .allDone i {
    outline:0 !important;
  }
  
  @keyframes allDone {
    50% { transform:translate(-50%,-50%) scale(1.2); }
  }
  
  #clicks {
    font-size:8px;
    font-family:monospace;
    position:absolute;
    bottom:5px;
    right:5px;
  }