Visibility on mobile devices

I am the administrator for https://potomacgoppatriots.org/ using the Highend theme. The site looks fine on a computer but the mailto function on the left of the header and the donate link (button) are not visible on mobile devices. I was able to get the social media items on the header to appear with the following CSS code:

@media handheld,only screen and (max-width:900px){
#header-bar.style-1 .top-widget { display: none }
#header-bar.style-1 #top-socials-widget { display: block !important }
#header-bar { display:block !important; }
}

I tried adding a line similar to the third line of code, changing the word ‘socials’ to ‘button’, ‘mailto’, etc, but that did not work. What code is needed to get the mailto and button visible on mobile devices?