added fix for tests failing

see #3298

Author: didoo

showcase/app/index.html

@@ -16,6 +16,7 @@
   {{content-for "head"}}
 
   <!-- these styles are pre-compiled in the `components` package -->
+  <!-- IMPORTANT: if you add a new entry here, you HAVE TO add it also to the `showcase/tests/index.html` file, which is used to run the tests -->
   <link id="hds-components-stylesheet" integrity="" rel="stylesheet"
     href="{{rootURL}}assets/styles/@hashicorp/design-system-components.css">
   <link integrity="" rel="stylesheet"

showcase/tests/index.html

@@ -14,6 +14,7 @@
     {{content-for "head"}}
     {{content-for "test-head"}}
 
+    <link href="{{rootURL}}assets/styles/@hashicorp/design-system-components.css">
     <link rel="stylesheet" href="{{rootURL}}assets/vendor.css">
     <link rel="stylesheet" href="{{rootURL}}assets/showcase.css">
     <link rel="stylesheet" href="{{rootURL}}assets/test-support.css">