Validation icons become too small when used on .custom-select

Created by: reefdog

When using the .has-danger/.form-control-danger classes on a .c-select custom menu, the .c-select's background-size overrides the .form-control-danger's, making the validation icons really tiny.

JSFiddle: https://jsfiddle.net/rjp4ys24/2/

Screenshot ("Name" is a text input and looks correct; "Country" is the custom select menu):