refactor(ripple): reduce CSS size

Reduces the size by removing private (`--_*`) custom properties. These are not needed since the component does not share styles across variants.

Size before: 1293b / 532b gzip
Size after: 1171b (-9%) / 502b gzip (-0.2%)

PiperOrigin-RevId: 600917333

Author: asyncliz

ripple/internal/_ripple.scss

@@ -26,12 +26,11 @@
 
 @mixin styles() {
   $tokens: tokens.md-comp-ripple-values();
+  @each $token, $value in $tokens {
+    $tokens: map.set($tokens, $token, var(--md-ripple-#{$token}, #{$value}));
+  }
 
   :host {
-    @each $token, $value in $tokens {
-      --_#{$token}: var(--md-ripple-#{$token}, #{$value});
-    }
-
     display: flex;
     margin: auto;
     pointer-events: none;
@@ -66,7 +65,7 @@
     }
 
     &::before {
-      background-color: var(--_hover-color);
+      background-color: map.get($tokens, 'hover-color');
       inset: 0;
       transition: opacity 15ms linear, background-color 15ms linear;
     }
@@ -75,7 +74,7 @@
       // press ripple fade-out
       background: radial-gradient(
         closest-side,
-        var(--_pressed-color) max(calc(100% - 70px), 65%),
+        map.get($tokens, 'pressed-color') max(calc(100% - 70px), 65%),
         transparent 100%
       );
       transform-origin: center center;
@@ -84,13 +83,13 @@
   }
 
   .hovered::before {
-    background-color: var(--_hover-color);
-    opacity: var(--_hover-opacity);
+    background-color: map.get($tokens, 'hover-color');
+    opacity: map.get($tokens, 'hover-opacity');
   }
 
   .pressed::after {
     // press ripple fade-in
-    opacity: var(--_pressed-opacity);
+    opacity: map.get($tokens, 'pressed-opacity');
     transition-duration: 105ms;
   }
 }