diff --git a/CHANGELOG b/CHANGELOG
index e05095887e27f2c0f644c963053585a9505f0314..48fe73954861f1845918b3821c77616ca33f4a0d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -22,6 +22,7 @@ v 8.4.2 (unreleased)
     improvement when checking if a repository was empty
   - Add instrumentation for Gitlab::Git::Repository instance methods so we can
     track them in Performance Monitoring.
+  - Increase contrast between highlighted code comments and inline diff marker.
 
 v 8.4.2 (unreleased)
   - Fix method undefined when using external commit status in builds
diff --git a/app/assets/stylesheets/highlight/dark.scss b/app/assets/stylesheets/highlight/dark.scss
index 41a4579e1bc8db42748c935f27d72355f3b923b2..b794da2ce9805cd477eb62c9e95174754aca6014 100644
--- a/app/assets/stylesheets/highlight/dark.scss
+++ b/app/assets/stylesheets/highlight/dark.scss
@@ -22,11 +22,11 @@
   // Diff line
   .line_holder {
     .diff-line-num.new, .line_content.new {
-      @include diff_background(rgba(51, 255, 51, 0.1), rgba(51, 255, 51, 0.3), #808080);
+      @include diff_background(rgba(51, 255, 51, 0.1), rgba(51, 255, 51, 0.2), #808080);
     }
 
     .diff-line-num.old, .line_content.old {
-      @include diff_background(rgba(255, 51, 51, 0.2), rgba(255, 51, 51, 0.3), #808080);
+      @include diff_background(rgba(255, 51, 51, 0.2), rgba(255, 51, 51, 0.25), #808080);
     }
 
     .line_content.match {
diff --git a/app/assets/stylesheets/highlight/monokai.scss b/app/assets/stylesheets/highlight/monokai.scss
index 22cee1af39f50b484d9a492e7e80b7d5329d2790..9098e07adcd793aad582ea01bf9b2e6c42837a29 100644
--- a/app/assets/stylesheets/highlight/monokai.scss
+++ b/app/assets/stylesheets/highlight/monokai.scss
@@ -22,11 +22,11 @@
   // Diff line
   .line_holder {
     .diff-line-num.new, .line_content.new {
-      @include diff_background(rgba(166, 226, 46, 0.2), rgba(166, 226, 46, 0.3), #808080);
+      @include diff_background(rgba(166, 226, 46, 0.1), rgba(166, 226, 46, 0.15), #808080);
     }
 
     .diff-line-num.old, .line_content.old {
-      @include diff_background(rgba(254, 147, 140, 0.2), rgba(254, 147, 140, 0.3), #808080);
+      @include diff_background(rgba(254, 147, 140, 0.15), rgba(254, 147, 140, 0.2), #808080);
     }
 
     .line_content.match {
diff --git a/app/assets/stylesheets/highlight/solarized_dark.scss b/app/assets/stylesheets/highlight/solarized_dark.scss
index 0e8f30b4b0bed5dcc3020f77cc688a2364cf3974..8b1a2824f76c78bffd35f8ddef42caa37f17241f 100644
--- a/app/assets/stylesheets/highlight/solarized_dark.scss
+++ b/app/assets/stylesheets/highlight/solarized_dark.scss
@@ -22,11 +22,11 @@
   // Diff line
   .line_holder {
     .diff-line-num.new, .line_content.new {
-      @include diff_background(rgba(133, 153, 0, 0.2), rgba(133, 153, 0, 0.3), #113b46);
+      @include diff_background(rgba(133, 153, 0, 0.15), rgba(133, 153, 0, 0.25), #113b46);
     }
 
     .diff-line-num.old, .line_content.old {
-      @include diff_background(rgba(220, 50, 47, 0.3), rgba(220, 50, 47, 0.3), #113b46);
+      @include diff_background(rgba(220, 50, 47, 0.3), rgba(220, 50, 47, 0.25), #113b46);
     }
 
     .line_content.match {
diff --git a/app/assets/stylesheets/highlight/solarized_light.scss b/app/assets/stylesheets/highlight/solarized_light.scss
index 08b6c83590740371898619d986ea37ae4e5c36f6..7ad89dd2c7c3ae0acb7cf141ccdf93b831652658 100644
--- a/app/assets/stylesheets/highlight/solarized_light.scss
+++ b/app/assets/stylesheets/highlight/solarized_light.scss
@@ -22,11 +22,11 @@
   // Diff line
   .line_holder {
     .diff-line-num.new, .line_content.new {
-      @include diff_background(rgba(133, 153, 0, 0.2), rgba(133, 153, 0, 0.3), #c5d0d4);
+      @include diff_background(rgba(133, 153, 0, 0.2), rgba(133, 153, 0, 0.25), #c5d0d4);
     }
 
     .diff-line-num.old, .line_content.old {
-      @include diff_background(rgba(220, 50, 47, 0.2), rgba(220, 50, 47, 0.3), #c5d0d4);
+      @include diff_background(rgba(220, 50, 47, 0.2), rgba(220, 50, 47, 0.25), #c5d0d4);
     }
 
     .line_content.match {