Customising site title and tagline

Hi, I’m having trouble with my site title and tagline. I can’t find a way to change their colours, and the tagline only shows if I enter it via the theme settings. In the Customiser it doesn’t show at all. In Vantage Premium theme design I’ve been able to change the site title font but I cannot change the site title colour. I can’t change the font of the tagline at all.

Ideally I would like to centre the title then centre the tagline below it but can’t see how to do this either

Thanks
sue