Change active tab color

It doesn't appear that this particular theme has any CSS set for an active tab to stay highlighted a certain color.

WordPress automatically outputs an "active" class for the list item that's currently active, so you'd just have to provide your own CSS for that class.

Post in the Elegant Themes forum and either Nick (the owner of Elegant Themes) or one of his support guys can give you the exact CSS you'll need to do what you want.

Is it possible for us to have a look at the CSS of another theme with active tabs highlighted and use that code? If yes, please let me know. I can give you the CSS of a different theme.

Sure, but unless it's the same theme, different CSS isn't going to do you much good.

The best thing to do here would be to ask the guys who built the theme for the correct code to do what you want.

You could write your own, but that doesn't seem like something you can do, given your question.

Alright. I posted a question on their forum. Thanks!

If possible, please answer this question:
https://www.experts-exchange.com/questions/26947265/Reduce-the-gap-between-logo-and-main-menu.html

Could you tell me where exactly and in which file I need to add this line of code?
Thanks!

anywhere in your stylesheet... style-Default.css

Somewhere around Line 113 if you want to keep it with the rest category navigation styles

It doesnt seem to work.

For a custom menu, we need to use this code:
#categories ul li.current-menu-item{ background-color: #FFFFFF; }

Try this

#categories ul li.current-menu-item a {backgound-color:#76a0b0;}

That doeesn't work. This line of code works partially:
#categories ul li.current-menu-item, #categories ul li.current-menu-parent{ background-color: #76a0b0; }

But, this does not work for a submenu item of a submenu. I think it needs to be iterative.
I'm assuming that it may not work for pages which are children of the children of a page on the main menu.