Invalid decimal literal error that isn't actually an error

[WorkOLS]

So I'm trying to use VS Codium, and I know I must be doing something wrong. I've been going through different text programs, all of which seem to work in Notepad++, but not when run with VS Codium. Here is the code:

And here is the error:

As you can see, "640px" is a perfectly valid CSS number. Note also that the specific code doesn't matter. If I were to backspace over this line, the error would simply move to the next number. If I enter different code into VS Codium, the error persists. Clearly this is something wrong with the IDE, but I have no idea how to fix it. What do I do?

Note: I am a noob. Please answer this question as you would a 10 year old.

[daiyam]

Please answer this question as you would a 10 year old.

Ask your mom. 😉

It's an error from one of your installed extensions. Without any extensions, I can't reproduce the issue.
Maybe a linter?

Try the command > Help: Start Extension Bisect

[WorkOLS]

Okay, where do I write that command?

[daiyam]

Ctrl+Shift+P then Help: Start Extension Bisect

[itxashancode]

Your error says "Invalid decimal literal" and you're seeing it on CSS numbers like 640px. That's not a VS Codium bug - it's your linter. The message means something is trying to parse "640px" as a number, not a CSS value. That usually happens when an extension like stylelint or a CSS validator is installed. Those tools expect pure numbers, not units.

If you don't want linting at all, open the command palette (Ctrl+Shift+P), type "Extensions: Show Installed Extensions," find any CSS or stylelint-related ones, and disable or uninstall them. If you want to keep linting but fix the rule, open your workspace settings (Ctrl+,), search for "stylelint," and look for something like css-number-no-unit or similar. Turn it off.

I ran into this last year when I installed a stylelint extension that was too strict. Disabling it made the red squiggles go away instantly.