Credit goes to clsr for helping with this.

This reverts commit 79fbcfb4a236650b2ee48569729947878e997466.

Sync with Pomf 2.0.x maint branch.

- css: Add missing Bootstrap license header (Expat)

Bootstrap is a CSS framework by Twitter, Inc.

Pomf uses certain Bootstrap 3 elements, such as .jumbotron and .alert.
The credit is due for Twitter, Inc. for Bootstrap, which like Pomf is
free software licensed under the Expat license.

The CSS snippets about Bootstrap were initially introduced to
style.min.css in commit df6cf936d7ef3a819c6ff484b24a8cb5946726a9, then
moved into pomf.css uncompressed in commit
152c0257a8ef9a8da7e45717a65578c340a7c178.

See: https://getbootstrap.com/

Reviewed-by: Eliot Whalan <ewhal@pantsu.cat>

Remove page specific style rules. These are unused relics from before
2.0.0 release.

This merge compliments 7743e0ec4e1c71e7cc0e0df6203e02d221c82721, which
was merged too early.

The tools page has only had alive and maintained tools on it since Pomf
2.0.0. Ded and old tools have been removed in commit
627937d0fa632a677f278af467886915c0a36f35.

It is anticipated that these style rules will be never used again. If we
did, we can add them back later: "you aren't gonna need it" (YAGNI). If
it's dead, you should probably remove the tool from the tools page
instead of beating a dead horse.

[wub@partyvan.eu: Modified Git commit message, as discussed]
Signed-off-by: Juuso Lapinlampi <wub@partyvan.eu>

Acked-by: Eliot Whalan <ewhal@pantsu.cat>