Merge branch 'Fix-example-code-for-replacing-css-with-util-classes' into 'master'

Fix example code for replacing css with util classes

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/168209



Merged-by: Peter Hegman <phegman@gitlab.com>
Approved-by: Vanessa Otto <votto@gitlab.com>
Approved-by: Peter Hegman <phegman@gitlab.com>
Reviewed-by: Vanessa Otto <votto@gitlab.com>
Co-authored-by: James Rushford <jrushford@gitlab.com>

doc/development/fe_guide/style/scss.md

@@ -222,7 +222,7 @@ In the following example, you add the utility classes `gl-fixed` and `gl-inset-x
 <style>
   .my-class {
     top: $header-height;
-    z-index: 999;
+    min-height: $comparison-empty-state-height;
     position: fixed;
     left: 0px;
     right: 0px;
@@ -235,7 +235,7 @@ In the following example, you add the utility classes `gl-fixed` and `gl-inset-x
 <style>
   .my-class {
     top: $header-height;
-    z-index: 999;
+    min-height: $comparison-empty-state-height;
   }
 </style>
 ```