italicise site title

Can you tell me how to italicise site title. I am using segoe ui font, and presently have the site on a kadence theme which I'm attempting to replicate onto GP on a staging site. I can make it happen it the inspector under the element, but not in the custom css

after searching >>

It looks like the real question might be how to add Segoe UI Italic to my fonts? and I don't know how to do that either?

Thanks