Increasing Header Height in Mobile

Hi there! I have a background video in my homepage header that formats fine on desktop but not on mobile due to the template I am using (Foster Juice Co). 

Does anyone have a code that would allow me to change the height of this header so the entire video is displayed in mobile view?

I've attached a screenshot, but my website is rebootfc.com.

Appreciate any point in the right direction!

Add to Design > Custom CSS > then save & reload the site

@media screen and (max-width:900px) {
section#home-banner {
    height: 250px;
}
}