where is the css for mobile header?

i can’t find the css to do this anywhere 

https://stackoverflow.com/questions/19827236/bootstrap-3-apply-css-on-mobile-view-only

The css is the same...just add a what width of the screen will be affected by the css.

thanks john but i know nothing about writing css. i just know how to change the hex code. so where do i find it for the 2 buttons in my screenshot?

If you're using the Material template, it's in:
/PF.Site/flavors/material/flavor/bootstrap.css

You will be looking for the class called:
.guest-login-small a.btn

Then you can change the hex for the background in there. In the demo, the class is around line 41243

There's several variations of that class, but you will be looking for the one that is under the section that starts with
@media (max-width: 480px) {
Since that one controls the appearance of those buttons on devices with a screen size of 480px or smaller.

I hope this helps!

ahh thank you! i was looking in the css in the themes section of the admincp.

THANK YOU SO MUCH!! PERFECTO!!!

Has the location of where to edit the css for the mobile header changed? I can't seem to find it. Can someone fill me in on the location?

nvm. found it. i was using my search tool incorrectly.