How to make such lines, with a:hover?

Question

css

Can you please tell me how to make such a line above the menu links?
https://nikbard.github.io/creatives/

Answer 1

I don't really understand what line, but you can do it like this:
border-top: 6px solid #ccc;

Answer 2

Nivo Slider is not bad, it makes previews itself. There were no problems with it
dev7studios.com/plugins/nivo-slider