#1352: fix deprecation warning (#1359)

src/scss/_bootstrap-override.scss

@@ -72,4 +72,11 @@
   $active-color: null
 ) {
   // Override bootstrap core
+}
+
+//
+// TODO: remove when https://github.com/twbs/bootstrap/pull/37425/ will be released
+//
+@function opaque($background, $foreground) {
+  @return mix(rgba($foreground, 1), $background, opacity($foreground) * 100%);
 }

src/scss/_config.scss

@@ -5,4 +5,4 @@
 @import "mixins";
 
 @import "bootstrap-config";
-@import "mixins-override";
+@import "bootstrap-override";

src/scss/mixins/_functions.scss

@@ -44,4 +44,5 @@
     @error "breakpoint `#{$name}` not found in `#{$breakpoints}`";
   }
   @return if($n > 1, nth($breakpoint-names, $n - 1), null);
-}
+}
+