put back PR request #53: alphagov/rems-to-px
Revert "put back PR request #53: alphagov/rems-to-px"

This reverts commit 7fe803c7351e7bb8f068d043321cd3e69bbed4d8.
put back PR request #53: alphagov/rems-to-px
styling update

* update colour variables to match the ones in the new frontend toolkit version
* use the buttons mixin from the frontend toolkit
Merge pull request #56 from alphagov/upgrade-frontend-toolkit

Upgrade frontend toolkit