No need to go elsewhwere! As well as having a number of builtin themes (Tools > Options > Appearance), Joplin has fully customisable UI in terms of colours/sizes/text alignments/etc if you know a little CSS, there's a TONNE of posts on here about different colour schemes people use, anything you can do with CSS, you can also do to your UI!
EDIT: This post is a good place to start if you're doing your own customisations