Update 'next-3.x' with latest changes from 'main'

bin/css/buttons.css

@@ -28,16 +28,11 @@ a.qui-button,
     float: none; /* qui-button reset */
 }
 
-button > .fa,
-.btn > .fa {
+button > .fa:not(:only-child),
+.btn > .fa:not(:only-child) {
     margin-right: .75rem;
 }
 
-button.loading > .fa,
-.btn.loading > .fa {
-    margin-right: 0;
-}
-
 /*****************************/
 /* button primary & standard */
 /*****************************/