Help with custom code that I dont understand

Hi so I cloned a website on webflow and I really like the header animation. I noticed the site comes with the following custom code

Body { -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; font-size: 1.1111111111111112vw; } /* Min Font Size */ @media screen and (max-width:991px) { body {font-size: 11.011111111111111px;} }

The issue is, this code changes all of the font sizes on my webpage but without this code the header images are not the correct size and the animation seems to not work. Is there anyway I can make this code only work on the header so it does not alter the font sizes of everything on my webpage.

this is the link to the site I copied

If element sizing across the site has been done in rems, then changing the body font size will indeed effect everything else.