Ocean Mist modification

I’ve been using the free Ocean Mist theme for a couple of years now on my site Spatial Scrawl and I’m now looking to draw more attention to my sub-pages (not just the homepage). I’m looking for the best way to do this – as you can see with this theme, the tabs are very small.

If I wanted to increase them or customize this area, how difficult would this be? I’m not that proficient with CSS but could get others involved.

If that’s more trouble than it’s worth, perhaps a “floating menu” to highlight my sub-pages instead of hoping someone notices the tiny sub-page tabs that my theme uses by default.

Suggestions are appreciated, thanks