First of all good job. Nice, clean layout. I have a few suggestions:
A very slight enlargement of the Whonix logo.
I feel the light blue backdrop of the top banner is a bit over used by software sites in general see: https://syncthing.net/. Can you please try a mock-up with a light green gradient? The download button is good as it is.
The light brown bottom banner in the bottom can benefit from changing to a shade of green matching the top banner - solid fill not gradient.
The icon for “isolation” can look like a vault door.
The compatibility icon can have a miniature Debian logo on it cut out like stencil on the puzzle piece.
“Keep your anonymity with Whonix” can be better read “Protect your privacy with Whonix”
Avoid the word free because its ambiguous →
“A libre software and open network…”