Header Menu Bar Not Being Displayed Correctly

Hi, my issue is that the header menu bar is not being displayed correctly when you slightly minimize your browser tab. When you do it, it looks as a rectangle instead of that original “v” shape that the Crystal Skull original theme has. How can I solve this? I don’t find any option in Theme Options to edit this :/ You can see the issue in these two pictures:

The problem

https://gyazo.com/12cf9c6147ce65ff98177edabb4f31cb

I want my header menu bar to look like in the demo but I don’t find any option in Theme Options nor in Appearance :/

https://gyazo.com/34487e8361b5a50668317d57606bfb8f

Thank you Support!