<!DOCTYPE html>
<html>
<style>
#escaped-unicode-space::before {
content: 'string with \00ff space is omited ';
}
#escaped-unicode-count::before {
content: "string with \0000fff one f is extra ";
}
#escaped-unicode-other::before {
content: "string with \0ffg g is not hex digit ";
}
</style>
<body>
<div id="escaped-unicode-space">div-text</div>
<div id="escaped-unicode-count">div-text</div>
<div id="escaped-unicode-other">div-text</div>
</body>
</html>