html: Lowercase the html colors, and make the comparison more robust.

Change-Id: I5fb3b1c8ea3692864707489ff9a82b78c5647d4a
html: Make GetColor() working in lower case.

To be consistent with the rest that works in lower case now.

Change-Id: I6fe40e71393230bbde8e283b1f98479bf644c610