fix(back-button): default md color is inhered

core/src/components/back-button/back-button.md.vars.scss

@@ -4,4 +4,4 @@
 // --------------------------------------------------
 
 /// @prop - Text color of the back button
-$back-button-md-color:               $toolbar-md-text-color !default;
+$back-button-md-color:               currentColor !default;

core/src/components/back-button/back-button.tsx

@@ -63,6 +63,8 @@ export class BackButton implements ComponentInterface {
       'ion-activatable': true,
       class: {
         ...createColorClasses(this.color),
+
+        // ion-buttons target .button
         'button': true,
         'show-back-button': showBackButton
       }

core/src/components/buttons/buttons.ios.scss

@@ -5,7 +5,7 @@
 // iOS Toolbar Default Button
 // --------------------------------------------------
 
-::slotted(*) ion-button.button {
+::slotted(*) ion-button {
   --padding-top: 0;
   --padding-bottom: 0;
   --padding-start: 5px;
@@ -16,7 +16,7 @@
   font-weight: 400;
 }
 
-::slotted(*) .button:not(.button-round) {
+::slotted(*) ion-button:not(.button-round) {
   --border-radius: #{$toolbar-ios-button-border-radius};
 }
 

core/src/components/buttons/buttons.md.scss

@@ -4,7 +4,7 @@
 // Material Design Toolbar Default Button
 // --------------------------------------------------
 
-::slotted(*) ion-button.button {
+::slotted(*) ion-button {
   --padding-top: 0;
   --padding-bottom: 0;
   --padding-start: 8px;
@@ -16,7 +16,7 @@
   font-weight: 500;
 }
 
-::slotted(*) .button:not(.button-round) {
+::slotted(*) ion-button:not(.button-round) {
   --border-radius: #{$toolbar-md-button-border-radius};
 }
 

core/src/components/buttons/buttons.scss

@@ -13,7 +13,7 @@
 // Toolbar Buttons
 // --------------------------------------------------
 
-::slotted(*) .button {
+::slotted(*) ion-button {
   --margin-top: 0;
   --margin-bottom: 0;
   --margin-start: 0;