Tumblr themes: Make your site title bigger
To start click the 'Edit theme' icon on the top right of your logged in home page to open the edit side panel.
There are a number of options that allow you to get the site title just how you want it.
Title letter spacing - this makes the this makes the site and post titles more 'gappy'
Main title size - you can select Default, Medium or Large here from the dropdown
Capitalize titles - this makes the site and post titles UPPER CASE
Title font - selects the font used on the site and post titles
Bold main title - this makes the site and post titles bold