serenity/Tests/LibWeb/Ref/css-read-only-read-write-selectors.html

<style>
    body :read-write {
        background-color: green;
    }
    body :read-only {
        border: 4px solid magenta;
    }
</style>
<input type="text" readonly>
<input type="text">

<p>Well hello friends</p>
<p contenteditable>Well hello friends</p>