feat(ripple): Reduce press opacity by 25% (#4350)

packages/mdc-ripple/_variables.scss

@@ -25,18 +25,23 @@ $mdc-ripple-fade-out-duration: 150ms !default;
 $mdc-ripple-translate-duration: 225ms !default;
 $mdc-states-wash-duration: 15ms !default;
 
+// Notes on states:
+// * focus takes precedence over hover (i.e. if an element is both focused and hovered, only focus value applies)
+// * press state applies to a separate pseudo-element, so it has an additive effect on top of other states
+// * selected/activated are applied additively to hover/focus via calculations at preprocessing time
+
 $mdc-ripple-dark-ink-opacities: (
   hover: .04,
   focus: .12,
-  press: .16,
+  press: .12,
   selected: .08,
   activated: .12
 ) !default;
 
 $mdc-ripple-light-ink-opacities: (
   hover: .08,
   focus: .24,
-  press: .32,
+  press: .24,
   selected: .16,
   activated: .24
 ) !default;