Patched to adhere to style changes of Textual 4.1.4

Textual has undergone some changes to the styling system. See https://github.com/Codeux/Textual/commit/e58f03c8d0cc6713b53abdf904d550d2f8255a66.

This patch adds styling to the tags that were changed, but aims to retain legacy compatability with older versions of Textual as well.