change the product mobile layout

I need to change the layout of the product description for mobile version.

First, how do I make the title font smaller. I did try to go into design-fonts styles-assign fonts- item(product) title, but it does not change something at all.

Second, how to make the spacing between the title and price smaller?

And last, how to make the "add to cart" button proportianate to "quantity" button?

I attached the screenshot below for better understanding. The link for product page is: https://www.vizniuk.com/everything/p/white-tee

Thank you!

Also, I had another question about product page.

How do I add a page link "size charts" on the product page, below the "choose size" button?

Thanks again.

Thank you so much, Tuan!!

23 hours ago, tuanphan said:

#1. #2.Add to Design > Custom CSS

@media screen and (max-width:767px) {
h1.pdp-details-title {
    font-size: 20px;
    margin-bottom: 0px !important;
}
div.sqs-add-to-cart-button {
    padding-top: 10px !important;
    padding-bottom: 10px !important;
}
}

#3. You can add a Button Block in Additional Info, then we can give code to move it under choose size button & turn button style to link style

is there any other option to do the size chart, without putting it in additional info?

or do I need to put it in in all of those?

22 hours ago, alexvizniuk said:

is there any other option to do the size chart, without putting it in additional info?

or do I need to put it in in all of those?

Same size chart link for all products or different? If different, the easiest way is add to Additional, if same, let me know, we will give a script code to add it for all products