How can I modify font sizes in the mobile version?

Hi folks, I have an issue with my website and could use your support.

Unfortunately, my uploaded custom font is displayed way too large in the mobile template, and I would like to adjust the size. How can I change the font sizes for individual headings (h1, h2, etc.) specifically for the mobile version? I would be grateful for your help!
 

Site: https://maltemartenmethod.squarespace.com/
Pword: maltemartenmethod2023

Use this CSS code (Website Tools > Custom CSS)

@media screen and (max-width:767px) {
	h1 {
		font-size: 30px !important;
}
	h2 {
		font-size: 20px !important;
}
	h3 {
		font-size: 10px !important;
}
}