I have installed Elementary Plus for adding additional icons that follow elementary os principles. However, I have only firefox icon remained non-themed. I wonder why such important app still not have an icon. Is there a way to get nice-looking icon for firefox?
Hey jakie there sure is buddy. Take a look at this HowTo I made for exactly that. As for the icon not sure which style you want but you can just google image Firefox icon.
There's a "native" app for that now in store called AppEditor. It follows eos guidelines. Code (Text): sudo apt-get install com.github.donadigo.appeditor