Help with navigation bar

Hello, ive been trying to change the size of the background for the navigation bar but i just can’t seem to do it.
All the code ive found from searching around can make it bigger and smaller to a certain point. but it won’t go as small as id like.

One of the codes i used was

/* navbar adjust padding */
.navbar-inner { padding-top: 16px; }
.navbar.resp .navbar-inner { padding-bottom: 4px; }

if i make the numbers bigger it certainly gets bigger. But if i put them to 0 at a certain point it just wont get any smaller.

Any help would be greatly appreciated. Thank you for your time