Changing font sizes in mobile view without changing in computer view

Hi! 

We were looking for some guidance on if there’s a way to change the size of our fonts in mobile view without changing it in computer view using codes? This would be used across multiple pages We have no background knowledge of coding. We are also hoping to resize a video.

You can share link to site & let me know which elements you want to change size, we can help easier

For example, if you want to resize h1, h2, h3, p1 only, you can use this code to Website > Website Tools > Custom CSS

@media screen and (max-width:767px) {
	h1 {font-size: 28px !important;}
	h2 {font-size: 28px !important;}
	h3 {font-size: 28px !important;}
	p.sqsrte-large {font-size: 28px !important;}
}