[tannhaeuser]

Not responsive, presenting the same layout on mobile and desktop

3-column grail layout (not bad per se, and not badly done at all, just something that was chased in the 90/00s to the extent that it looks dated - still could be ok for the intended target audience)

Why are there two nav menus? The horizontal menu appears to contain the same links as the vertical one, or the first couple items of it

Center body text doesn't have margin/padding

In general, allow content to have space rather than trying to cram everything into the first page impression; there are exceptions, though

What's the central message/tagline for the ATS site? The teaser syntax examples in the right column, with proper typo, are about the stuff that should be featured as central or only content

+1 for crafting a site for your project in the first place