How to change the underline on hover and active main navigation items - dawn theme

Thanks for this. I’ve implemented this but have a couple of questions. How can i stop the hover state line being wider than the active state line? i want them to be the same width (ideally active state width).
Also, the line on click of the menu item is too thick or sometimes seems to double up, how can i reduce it?

Is there a way i can get the SHOP Menu item to remain active when clicking through to a product ? at the moment it disappears

Lastly, is there a way i can reduce the space slightly between the logo and the menu items, similar to bybillie?

Many thanks