www.wysiwygwebbuilder.com

https://www.payrexx.com/en/features/one-page-shop/
You will get a one page shop with many features and a lot of payment gateway providers. You will get a dedicated link and you can sell even you do not have a website. If you want to integrate the shopping page use an iframe.

There is a ready extension available on http://lucknowwebs.com/cms-shopping-car ... and-above/
or a script that you can integrate in your website available on https://www.phpjabbers.com/php-shopping-cart-script/

Yes, freezes at the contact form.

Same issue on smartphone, it freezes at the half.

I would set the menu fixed and the back to top arrow too, going up and down distracts the visitors attention.(on smartphone layout)

Problem persists on smartphone, the menu button is not visible.

It happens on desktop too if you scroll to the right.

Clean and nice design, problems on http://www.silkandlaceboudoir.com/sessioninfo.html, looks like it is not optimized for smartphones, blank space on the right. Make the form rectangles aligned to the left at the same distance so the borders could make an invisible vertical line.

Terms and conditions not optimized for smartphone, looks like a desktop mini version, the footer is not fixed at the bottom, it is flexible.

Click the properties and select enable form.