Fix custom-select font size/padding (#26585)

fixes #26476

scss/_custom-forms.scss

@@ -220,15 +220,17 @@
 
 .custom-select-sm {
   height: $custom-select-height-sm;
-  padding-top: $custom-select-padding-y;
-  padding-bottom: $custom-select-padding-y;
+  padding-top: $custom-select-padding-y-sm;
+  padding-bottom: $custom-select-padding-y-sm;
+  padding-left: $custom-select-padding-x-sm;
   font-size: $custom-select-font-size-sm;
 }
 
 .custom-select-lg {
   height: $custom-select-height-lg;
-  padding-top: $custom-select-padding-y;
-  padding-bottom: $custom-select-padding-y;
+  padding-top: $custom-select-padding-y-lg;
+  padding-bottom: $custom-select-padding-y-lg;
+  padding-left: $custom-select-padding-x-lg;
   font-size: $custom-select-font-size-lg;
 }
 

scss/_variables.scss

@@ -526,10 +526,14 @@ $custom-select-focus-border-color:  $input-focus-border-color !default;
 $custom-select-focus-width:         $input-btn-focus-width !default;
 $custom-select-focus-box-shadow:    0 0 0 $custom-select-focus-width rgba($custom-select-focus-border-color, .5) !default;
 
-$custom-select-font-size-sm:        75% !default;
+$custom-select-padding-y-sm:        $input-btn-padding-y-sm !default;
+$custom-select-padding-x-sm:        $input-btn-padding-x-sm !default;
+$custom-select-font-size-sm:        $font-size-sm !default;
 $custom-select-height-sm:           $input-height-sm !default;
 
-$custom-select-font-size-lg:        125% !default;
+$custom-select-padding-y-lg:        $input-btn-padding-y-lg !default;
+$custom-select-padding-x-lg:        $input-btn-padding-x-lg !default;
+$custom-select-font-size-lg:        $font-size-lg !default;
 $custom-select-height-lg:           $input-height-lg !default;
 
 $custom-range-track-width:          100% !default;