Header changed for Web but not for mobile

Hello! I recently changed the header size using this code in the functions.php

add_theme_support( ‘custom-header’, array(
‘header_image’ => ”,
‘header-selector’ => ‘.site-title a’,
‘header-text’ => false,
‘height’ => 120,
‘width’ => 1260,
) );

In web view everything looks great, but when I look at it on mobile view the header is really small. Anybody know some code to separate web and mobile? The mobile view looked fine with the original settings. I am very new to WordPress so any help is much appreciated! Here is my site so you can take a look https://blog.bpabenefits.com