How to change the site title size for Mobile screen ?

Hi

Could someone please tell me how to change the font for the #site-title for a screen size for mobile. The default size is 22px I want it to be larger.

I tried this

@media (max-width: 480px) {
#site-title span a {
font-size: 32px;
line-height: 36px;
}
}

and this

@media screen and (max-width: 480px) {
#site-title span a {
font-size: 32px;
line-height: 36px;
}
}
But it is not saving the changes ,
Please help.
Thank You

Website: www.viaultra.com