Unable to change font family and link colours in full site editor

I’m trying to create my personal website/blog using the full site editor. I’ve chosen the “Block Builder” theme which is simply just a blank theme. I figured I’ll build the whole thing from scratch using the site editor.

But the problem is that I’m unable to change the font family or the colour of links in the “styles” section. When I click on the “styles” button and choose typography from the menu I don’t see an option to change font family. Similarly when I choose the colours option and click on links the whole menu just turns blank. I’d appreciate any help in fixing this.

Thanks in advance!

The page I need help with: [log in to see the link]