box with copy button

Text area code 

<br><br>
<textarea style="border-style: solid; border-width: 1px 1px 1px 20px; border-color: #4072a1; width: 100%; height: 300px; line-height: 16px; resize: none;" id="html1" readonly>





</textarea><div style="font-size:13px; font-family: comic sans ms; color: blue;"><button onclick="copyThis1()">Copy This Code </button></div>
<script>
function copyThis1() {
  var copyText = document.getElementById("html1");
  copyText.select();
  copyText.setSelectionRange(0, 99999)
  document.execCommand("copy");
  alert("Code snippet copied to clipboard");
}
</script>
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Online Syntax highlighting tool

https://tohtml.com/