Thanks for reaching out.
The main theme.co site is still Wordpress but with customization. You can achieve the same layout with Pro or X theme, you can also check an existing design from Pro's design cloud. https://theme.co/apex/forum#design-cloud
Let's do it with Pro, first, the floating icons and menu, you'll have to create a Pro header and assign it to your page or globally. Please check this https://theme.co/apex/forum/t/pro-header-and-footer-builder-introduction/103. You'll have to set your header bar position to absolute and change its background to transparent.
Then add two container within that header bar and add your images on each, make sure to align your container's image to the left and right. But it's automatic ( alignment ) if you created it from from scratch based on the above header setting. The result is similar to this but I tried the button instead of image.
As for content, you'll have to edit your page within the builder ( https://theme.co/apex/forum/t/knowledge-base-overview/287 Cornerstone / Content Builder ) and add sections with the applicable columns similar to theme.co
Then simply add content and elements to those columns making it similar to theme.co. Like image, buttons, and so on. Then just align them to the center by inspecting the columns and choose the center alignment.
As for the table layout, it should be the same as adding section, rows, and columns, but this time, you'll have to use the border option of the columns.
That should do it, the content depends on your preference but should be doable and achievable with Pro without custom CSS.