the temp panel

Here's my addition to styles.css. How about you try writing and implementing setup_temp() before looking at mine?

Use id's 100 to 103.

#temp_panel {
  display:flex;
  flex-direction: column;
  align-items: center;
  background-color: mediumseagreen;
  width:9vw;
}
.temp {
  width:90%;
  margin-top:1vmin;
}
<img src='cards/empty.png' class='temp' id='101' onclick='card_clicked(this);'>
function setup_temp() {
  var s1="<img src='cards/empty.png' class='temp' id='10";
  var s2="' onclick='card_clicked(this);'>";
  for (var i=0;i<4;i++) {
    document.write(s1+i+s2);
  }
}
<body>
  <div id='temp_panel'>
    <script>setup_temp();</script>
  </div>
  ...
</body>