Does <H1> make sense when.

[Mikey85]

es <H1> make sense when you edit the font size of the <h1> in css?

[victor]

Yes.

Heading tags are about logical structure.

CSS is how it is rendered in a particular instance (eg a visual browser like Firefox, or read out loud like with Jaws).

Some search engine spiders take some note of the logical structure, so omit it and you'll possibly confuse them.

Some humans take note of the logical structure too, so hide it too much and you'll possibly confuse them.