fix(stack): include styles for individual themes

Fixes #2417

Include stack stylesheet across all Carbon theme variants to ensure
stack component styles are available regardless of selected theme.

Author: metonym

css/all.css

@@ -24,6 +24,7 @@ $css--plex: true;
 @import "./popover";
 @import "./checkbox-readonly";
 @import "./text-area-warn";
+@import "./stack";
 
 @import "carbon-components/scss/globals/scss/_css--reset";
 @import "carbon-components/scss/globals/scss/_css--font-face";

css/g10.css

@@ -24,6 +24,7 @@ $css--plex: true;
 @import "./popover";
 @import "./checkbox-readonly";
 @import "./text-area-warn";
+@import "./stack";
 
 @import "carbon-components/scss/globals/scss/_css--reset";
 @import "carbon-components/scss/globals/scss/_css--font-face";

css/g10.scss

@@ -24,6 +24,7 @@ $css--plex: true;
 @import "./popover";
 @import "./checkbox-readonly";
 @import "./text-area-warn";
+@import "./stack";
 
 @import "carbon-components/scss/globals/scss/_css--reset";
 @import "carbon-components/scss/globals/scss/_css--font-face";

css/g100.css

@@ -24,6 +24,7 @@ $css--plex: true;
 @import "./popover";
 @import "./checkbox-readonly";
 @import "./text-area-warn";
+@import "./stack";
 
 @import "carbon-components/scss/globals/scss/_css--reset";
 @import "carbon-components/scss/globals/scss/_css--font-face";