Hey Gareth, welcome to the Community forum!
Improving the performance, seo and score of your website is always important.
We recently released a new version of the Toolbar, as mentioned in our progress page, and one of the things that we're more excited about is the fact that the Toolbar itself is way lighter than before:
"We drastically improved the performance of the toolbar script. This script is now almost ten times smaller than in the previous version. We managed to make it 100Kb lighter (from 120kb to 14kb) than previously. This will impact all users visiting your website and on the overall performances of your website."
To know if you have this newer version which includes code splitting and smaller file size you can check by typing prismic.version in your browser console for you website like so:
The version should be 4.0.0 , like above. If you don't have this then clear the cache in the browser to refresh and get then latest toolbar.
Although thus is not related to the font embedded into the toolbar, I thought you might want to hear this good news.
As for the styles of it, we don't recommend people to modify the script of the Toolbar because it may cause things to break. So we don't currently have an option to change de CSS properties of it.
Could you tell me in which way is this causing you problems in the dev process?
Thanks a lot