This host page applies deliberately hostile CSS — every button is hot-pink/28px and inputs are lime-green. The widget below is rendered in a Shadow DOM, so none of that leaks in. That's the isolation demo.
↑ The tip widget keeps its own styling despite the page trying to wreck all buttons/inputs.
<script src="/widget.js"
data-creator="Bilal"
data-currency="gbp"
data-amounts="3,5,10"
data-placement="inline"></script>