- inline CSS
The Source Editor button () in the WYSIWYG editor is your friend, as well as any other place where you can edit HTML source, such as the Custom Navbar box in Navbar settings (Group Admin panel). In these places you can use the above languages to achieve what you want to.
If you don't know any HTML or CSS, don't worry. I will be giving examples in these posts which in many cases you will be able to copy and paste partially or entirely as your needs require.