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The way we did it previously, Jenkins would start building from the release
branch, which would fail with "Not building from a tag, but last version in
changelog was released".

This reverts the remaining part of
commit:e54b9f7e, as our website looks ugly with
the breadcrumbs reintroduced if we keep these CSS bits.

refs: #12134

On #11911 it was said "They will be back in January once the donation campaign
is over", but apparently this was forgotten.

Partially reverts e54b9f7e, that did
two (related) things at a time: I've left the responsive header height part in
case it's still useful.

I've find it too hard to guess if this is going to break the test suite,
so let's see.

This reverts commit 6cd48d48.

This reverts commit 2919ff01.

This reverts commit 66f9201c.

https://www.apple.com/macos/

The Firefox merge window was bumped by one day due to Easter:

https://lists.torproject.org/pipermail/tbb-dev/2017-April/000503.html