Revert "Change remaining #mw-mf-header occurrences to .header"

This reverts commit 167aeba0d8933cab42d599a8e66fc0c8fc5e7f91

Change-Id: I0492b0c3ab0b06e4f9866f66abd33b98b0230270
Merge "Revert "Change remaining #mw-mf-header occurrences to .header""