Unfortunately, the CSS and JS elements mentioned in the report are required for the proper display of your 3dcart website. Eliminating or relocating these to the footer (as suggested by the report) will cause issues in the way the website displays.
Optimize CSS Delivery of the following
Moving the CSS to the footer would cause your site to load without any styles, making it look broken and providing a terrible user experience.
Google suggests you can "Optimize CSS delivery" by "inlining" it in your code.
These changes won’t necessarily improve the overall load time of your page, but it will increase your PageSpeed score, and may appear to load faster because the elements at the top of the page will load sooner. For visitors the server load time is more important since JS and CSS elements are cached after the initial load of the site.
For Google, the goal is to get a green score for the desktop version, and this usually can be achieved by optimizing the images on the site, which usually consists of re-formatting and compressing the images to reduce their respective sizes.