Reply To: New to CSS; Code works but still needs someone to check please

[I.m.learning]

I don’t normally use CSS Lint; but seems it does good with some errors compared to https://jigsaw.w3.org/css-validator/.

All it’s essentially stating is, if you’re not using a 0(zero) you should use some unit of measurement (px, rem, etc.). For your “*” selector, just put some unit, looks like you’re referencing px.
FROM
* {margin: 1; padding: 1;}
TO
* {margin: 1px; padding: 1px;}

What I understood, and maybe someone else can shed light on this, the at-rules are vendor-specific, meaning they won’t validate through CSS validation. If you test your code in major browsers (IE, Edge, Chrome, FF, Opera, and smartphones), and it works, I wouldn’t concern myself too much.