feat(modal): ensure header and content background color is inherit from modal

Author: joselrio

core/api.txt

@@ -667,15 +667,33 @@ ion-content,method,scrollToTop,scrollToTop(duration?: number) => Promise<void>
 ion-content,event,ionScroll,ScrollDetail,true
 ion-content,event,ionScrollEnd,ScrollBaseDetail,true
 ion-content,event,ionScrollStart,ScrollBaseDetail,true
-ion-content,css-prop,--background
-ion-content,css-prop,--color
-ion-content,css-prop,--keyboard-offset
-ion-content,css-prop,--offset-bottom
-ion-content,css-prop,--offset-top
-ion-content,css-prop,--padding-bottom
-ion-content,css-prop,--padding-end
-ion-content,css-prop,--padding-start
-ion-content,css-prop,--padding-top
+ion-content,css-prop,--background,ionic
+ion-content,css-prop,--background,ios
+ion-content,css-prop,--background,md
+ion-content,css-prop,--color,ionic
+ion-content,css-prop,--color,ios
+ion-content,css-prop,--color,md
+ion-content,css-prop,--keyboard-offset,ionic
+ion-content,css-prop,--keyboard-offset,ios
+ion-content,css-prop,--keyboard-offset,md
+ion-content,css-prop,--offset-bottom,ionic
+ion-content,css-prop,--offset-bottom,ios
+ion-content,css-prop,--offset-bottom,md
+ion-content,css-prop,--offset-top,ionic
+ion-content,css-prop,--offset-top,ios
+ion-content,css-prop,--offset-top,md
+ion-content,css-prop,--padding-bottom,ionic
+ion-content,css-prop,--padding-bottom,ios
+ion-content,css-prop,--padding-bottom,md
+ion-content,css-prop,--padding-end,ionic
+ion-content,css-prop,--padding-end,ios
+ion-content,css-prop,--padding-end,md
+ion-content,css-prop,--padding-start,ionic
+ion-content,css-prop,--padding-start,ios
+ion-content,css-prop,--padding-start,md
+ion-content,css-prop,--padding-top,ionic
+ion-content,css-prop,--padding-top,ios
+ion-content,css-prop,--padding-top,md
 ion-content,part,background
 ion-content,part,scroll