Feedback needed, new to Squarespace we are up and running

Site URL: http://pelletlab.com

I am just getting started, please take a look I would welcome any feedback!  By the way, has anyone found a way to accept a Purchase Order as a form  of payment?  We sell often to schools that would like to use a PO.

I see search icon on homepage header is black. White should be better. You can add this to Design > Custom CSS to change its color

body.homepage header#header input {
    filter: invert(1);
    border-color: black;
}

The text HIGH QUALITY.. on mobile is super large. You can check. If need to resize, just comment below.

Search on Burger Overlay Menu is off centered.

With your question, you mean replace add to cart with a form?

Thanks!  Most of our orders are with a credit card, but occasionally by Purchase Order.  With Wordpress we were able to accept PO as a method of payment but not with Squarespace.  If a form option would be available maybe that would work?

It seems I am not the only one with the PO payment problem occasionally, from what I can see there is no way to work around this.  We will just have our customers fax or email a PO if it comes up.  But more an more a PO is not used so much by schools anymore.