There are 2 things needed to be done for this to work.
The first one is to add a single line of script to the page, turning the 'designMode' on:
<script>
document.designMode = "on"
</script>
The second one is to configure the display property of the <style> tag as 'block':
<style style="display:block">
body {
background: white;
font-size: 16px;
color: #333;
}
</style>
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