Revert "Changed alert background - it's now the same as the alert during the installation, making all links visible"

This reverts commit e4656375a7f64773d5d76656d49b2bae77b54f8f.
Revert "Whiten the links in .alert to make them readable."

This reverts commit 593c85dc44e8684f63218aceda81ae8ec6e81477.
Revert "Add background to alert message"

This reverts commit b9cf0a12bfb6f6fdbe8c9c6716461f0aff53c4fd.
Revert "Fix line-height on the install button (tested on Chrome on Ubuntu and Chrome Beta on Android)"

This reverts commit ab58045408760b6141246dcc412140cd89f97702.