Header title font jumps size upon scrolling on mobile devices

Site URL: https://goby-oarfish-j8jm.squarespace.com/

Password: tuanh3lp

Hello, I've notice that on a number of phone browsers my header text jumps size when you scroll (see attached video for reference).

I'd like it to look smooth and stay a consistent size when scrolling. 

If someone could provide some code to inject that would be fantastic.

Many thanks,

Ollie 

You can set fixed size for heading title

/* Heading title */
@media screen and (max-width:767px) {
div#block-f060dd1f373d13335896 h1 {
	font-size: 24px !important;
}
}

with div#block.. is block id. You can use this tool to find block id. 

Thanks Tuan, this worked perfectly!