Created by: pat270
@extend .form-control-lg; and @extend .form-control-sm; in _input-groups.scss adds some potentially unwanted css selectors.
.input-group-lg > .form-control-static.form-control
.input-group-lg > .form-control-static.input-group-addon
.input-group-lg > .input-group-btn > .form-control-static.btn
.input-group-lg > select.form-control
.input-group-lg > select.input-group-addon
.input-group-lg > .input-group-btn > select.btn
.input-group-lg > select.form-control:not([size]):not([multiple])
.input-group-lg > select.input-group-addon:not([size]):not([multiple])
.input-group-lg > .input-group-btn > select.btn:not([size]):not([multiple])adds similar selectors for .input-group-sm as well.
This puts .form-control-lg and .form-control-sm css properties in Sass placeholder to help reduce the number of selectors generated.