Fixes #26953 (closed).
We use more $input-
variables than $input-btn-
, but we had a few loose ends that made it a bit inconsistent in how we re-used those. In general now, we have $input-btn-
variables as an abstraction layer to connect our inputs and buttons together. When the styles are for inputs only, they should be using the $input-
variables instead of $input-btn-
ones.
/cc @twbs/css-review