Fix style issue with the selector-example. (#570)

styles.scss

@@ -181,17 +181,13 @@ input[type="number"].no-arrows {
 }
 
 .form-select {
-  min-height: 37px;
-  line-height: initial;
-  &-sm {
-    min-height: 31px;
-  }
   &:disabled {
     opacity: 0.65;
   }
 }
 
 .form-select, .form-control, .input-group-text {
+  line-height: initial;
   border: 0 !important;
   box-shadow: inset 0 -2px 0 0 #3a3a3a;
 }