@matthewhurst For the specific CSS you’re wanting, here is where to start.

The blog title is a simple h1 and can be modified like this in your custom CSS:

h1 { font-size: 1.5em; }

1.5em is the default. I recommend using em and trial-and-erroring until you get your right font-size. For reference, the post titles (h2) are set to 1.2em. Perhaps something between those would work?

To remove the link underlining, you can do it for every link across the site like this:

a { text-decoration: none; }

If you’re only wanting to target certain links (such as post titles), you can do it like this:

.post-title a { text-decoration: none; }

If any of that is not working as you expect, let me know, and we’ll figure it out. One thing to note…when editing CSS or the Footer, it can sometimes take a few seconds before it’s live on your site.