fix the way to apply scss

packages/core-styles/scss/bootstrap/theming/_dropdown-dark.scss

@@ -1,5 +1,5 @@
 @use '@growi/core-styles/scss/bootstrap/init' as bs;
 
 .dropdown-item:active{
-  --#{$prefix}dropdown-link-active-bg: #{( bs.$gray-700 )};
+  --#{$prefix}dropdown-link-active-bg: var(--#{$prefix}gray-700);
 }

packages/core-styles/scss/bootstrap/theming/_dropdown-light.scss

@@ -1,6 +1,6 @@
 @use '@growi/core-styles/scss/bootstrap/init' as bs;
 
 .dropdown-item:active{
-  --#{$prefix}dropdown-link-active-color: #{( bs.$gray-600 )};
-  --#{$prefix}dropdown-link-active-bg: #{( bs.$gray-200 )};
+  --#{$prefix}dropdown-link-active-color: var(----#{$prefix}gray-600);
+  --#{$prefix}dropdown-link-active-bg: var(----#{$prefix}gray-200);
 }