Css keeps validating 100
However you may always provide a fallback for browsers that do not support viewport-relative lengths using the old “height: 100%” option.
I’ve tested vh on Internet Explorer 9 and it is working great so far, but I’ve read that IE 8 doesn’t support it.
That is, it will check that it complies with the CSS standards set by the W3 Consortium.
There are a few which will also tell you which CSS features are supported by which browsers (since not all browsers are equal in their CSS implementation).
The origin of the problem is probably in some authoring program that has converted a normal SPACE to a NO-BREAK SPACE.
It looks like a space, walks like a space, quacks like a space, but it still isn’t a space, in CSS parsing.