This bookmarklet gives you a small code playground and allows you to copy your result as shareable dataurl.
data:text/html;charset=utf-8,<body oninput="var x=(h.value?h.value:'')+(c.value?'<style>'+c.value+'</style>':'')+(j.value?'<script>'+j.value+'<\/script>':'');document.querySelector('iframe').srcdoc=x;i.value='data:text/html;charset=utf-8,'+encodeURIComponent(x)"><style>*{box-sizing:border-box}body{margin:0}iframe,textarea{width:100%;height:49vh;float:left}textarea{font-family:monospace;width:33.33%}input{width:90%}button{width:10%;background:lightgrey}</style><input id=i type=text placeholder=dataurl readonly><button onclick="document.getElementById('i').select();document.execCommand('copy')">copy</button><textarea id=h placeholder=html></textarea><textarea id=c placeholder=css></textarea><textarea id=j placeholder=js></textarea><iframe>
adapted from this codepen