Changing size of site title without affecting size of mobile site-title

Hey, with the following code I want to change the size of the site title: .site-title, .site-title a { font-family: Avenir 85 Heavy !important; font-weight: bold !important; font-size: 50px !important; } However, it also changes the size of the site title in the mobile version disproportionately. The mobile size title can also become a bit bigger but it just becomes too big with the code. IS there any way to change it? Regards, Ben