diff --git a/app/assets/stylesheets/pages/issuable.scss b/app/assets/stylesheets/pages/issuable.scss
index da5c44b5fdc3f140bf42615556d48dd074657306..a53cc27fac92de409d1c6d3b5e99a47bb341b487 100644
--- a/app/assets/stylesheets/pages/issuable.scss
+++ b/app/assets/stylesheets/pages/issuable.scss
@@ -193,7 +193,6 @@
   top: $header-height;
   bottom: 0;
   right: 0;
-  z-index: 8;
   transition: width .3s;
   background: $gray-light;
   padding: 10px 20px;
diff --git a/app/assets/stylesheets/pages/tree.scss b/app/assets/stylesheets/pages/tree.scss
index 8fafe4726218399be28b97b1b7b70b61b6f8af97..948921efc0ba07a4edb1b902981b6adfda9da953 100644
--- a/app/assets/stylesheets/pages/tree.scss
+++ b/app/assets/stylesheets/pages/tree.scss
@@ -171,6 +171,8 @@
 .tree-controls {
   float: right;
   margin-top: 11px;
+  position: relative;
+  z-index: 2;
 
   .project-action-button {
     margin-left: $btn-side-margin;
diff --git a/changelogs/unreleased/28142-overlap-bugs.yml b/changelogs/unreleased/28142-overlap-bugs.yml
new file mode 100644
index 0000000000000000000000000000000000000000..9fdabdf204af6f4b318dc2fe7483fd815d1ac5f3
--- /dev/null
+++ b/changelogs/unreleased/28142-overlap-bugs.yml
@@ -0,0 +1,4 @@
+---
+title: Fix z index issues with sidebar
+merge_request:
+author: