Oh, well, so what? Those HTML checkers were designed without taking
grids into account, possibly even by someone running an attitude. I
have never had any problems with a grid displaying in a browser, and
have timed the page loading of the same page with and without a grid
and couldn't tell the difference on my wristwatch.
It's OK with me if others prefer not to use them. Hey, I didn't used
to drive Japanese cars. They killed some friends of mine before they
became cars. Not many people remember that a Kawasaki was a bomber
and a Mitsubishi was a hot fighter plane ... the "Zero". A classmate
of mine was on the carrier Wasp. One minute the Wasp was there, with
a bunch of Kamikazes flying Mitsubishis headed for it, then there was
an amazing explosion and when the smoke dissipated the Wasp was gone.
My cousin watched it from a nearby cruiser. Incredibly, the
classmate, Joe Sansing was his name, was blown overboard and was
picked up within hours with all his parts still attached.
Now I own a Subaru, made by Fuji Heavy Industries. My God. What did
they make? Probably battleships.
So I don't get too worked up about grids.