Trouble finding terminology...what is stuff called?

I need to modify my existing webpage. I’m brand new to Atom, I’ve always used NotePad before.
(no, not NotePad ++, but NotePad. I’m kind of a dinosaur)
I just learned css.

I often cannot figure out what feature to add, mainly because I do not even know what it is called. For example, it took me two hours of hunting to figure out that the cool and useful formatting is called “atom-beautify.”

Now, in beautify, I want to add those little vertical lines on the left side of the screen that connect opening and closing tags. What are they called? I can probably find and install them from there.

Likewise, I managed to figure out and install the “Molokai” theme. But it didn’t seem to change the “settings” menu colors (UI?), part of which is a dark gray on a darker gray…very difficult for me to read. I figured out how to increase the font size, which definitely helps. But can someone direct me to how to change Atom’s native menu colors?

Thank you…

The theme selector has a separate choice for syntax theme and UI theme.

If you are referring to the menu bar (File, Edit, View, etc.) that is controlled by the OS theme.