Posting markdown block with language specifier doesn't perform syntax/token highlighting

Just to get this out of the way, I just reviewed the “similar” posts but none of them that I was able to find were in reference to my specific case, the -->user<-- posting markdown code when using ChatGPT in a browser, only the ChatGPT bot’s markdown output, which is working fine.

So I’ve been trying to send markdown code with the language specifier as instructed by ChatGPT but when I look in the chatlog the markdown isn’t properly highlighted as one would expect and the language specifier shows up in plaintext on the first line of the markdown block I posted into chat. ChatGPT’s output is correct and is highlighted, but mine is not.

Example:

[```css
#PocketForm l {
	text-align: center;
	display: inline-block;
	outline: grey solid 0px;
	border-radius: 1em;
	padding: 0.75em;
	background: #FFFFFF;
	width: 100%;
}
#PocketForm t {
	text-align: center;
	font-weight: bold;
	font-size: 200%;
}
#PocketForm r {
	text-align: justify;
	font-weight: normal;
	font-style: oblique;
	font-size: 75%;
	max-width: 30em;
	display: inline-block;
}
#PocketForm my-cust-fieldset,
#PocketForm my-cust-legend {
	display: block;
}
#PocketForm my-cust-fieldset {
	border: 1px solid #ccc;
	border-radius: 1em;
	padding: 1.5em 1em 1em;
	margin-bottom: 1em;
	background: #F9F9F9;
	position: relative;
}
#PocketForm my-cust-legend {
	font-weight: bold;
	padding: 0.5em 1em;
	margin: -1.5em 1em 1em 1em;
	border-radius: 0.5em;
}
```]

This doesn’t work even though I’m following ChatGPT’s instructions to-the-letter. Is there something I’m doing wrong? Are ChatGPT’s instructions incorrect?