Links
Here's the thing about "unused CSS" tools
It seems unlikely that this analysis tool can handle all those possibilities. Even with loads of configuration, mock state, and integration testing, it couldn't cover the near-infinite possible permutations of all this.
Don’t Use The Placeholder Attribute
The placeholder attribute contains a surprising amount of issues that prevent it from delivering on what it promises. Let’s clarify why you need to stop using it.
input :not(:placeholder-shown)
If you're getting rid of your placeholder attributes, why not consider this clever CSS-only "moving label" pattern?
Container Query flow chart
Container Queries don't actually exist yet, so this flowchart of alternative techniques is very helpful.
Don't just copy the @font-face out of Google Fonts URLs
The issue is that Google does fancy Google things here and the contents of that original stylesheet changes based on the browser requesting it.
Videos
FaCSSt—CSS and Performance, by Harry Roberts
Ahh… CSS and performance. Two of my favourite things! But how well do they play together? It depends… In this very matter-of-fact talk, we’ll be looking at all of the different ways CSS can make our websites faster or slower. From the common and perhaps more obvious, to the unusual and obscure ways in which CSS can impact performance for better or worse.