diff --git a/course/format/classes/output/local/content/cm/completion.php b/course/format/classes/output/local/content/cm/completion.php
index 32252e865d3..e8874c25e94 100644
--- a/course/format/classes/output/local/content/cm/completion.php
+++ b/course/format/classes/output/local/content/cm/completion.php
@@ -122,13 +122,12 @@ class completion implements named_templatable, renderable {
         $dialogcontent = $output->render_from_template('core_courseformat/local/content/cm/completion_dialog', $completioninfo);
 
         $buttoncontent = get_string('completionmenuitem', 'completion');
-        $buttonclass = '';
+        $buttonclass = 'btn-subtle-body';
         if ($completioninfo->istrackeduser) {
-            $buttonclass = 'btn-outline-secondary';
             $buttoncontent = get_string('todo', 'completion');
             if ($completioninfo->overallcomplete) {
                 $buttoncontent = $output->pix_icon('i/checked', '') . " " . get_string('completion_manual:done', 'core_course');
-                $buttonclass = 'btn-success';
+                $buttonclass = 'btn-subtle-success';
             }
         }
 
diff --git a/course/templates/completion_manual.mustache b/course/templates/completion_manual.mustache
index 8cfe1b387f4..b2d1dddedbf 100644
--- a/course/templates/completion_manual.mustache
+++ b/course/templates/completion_manual.mustache
@@ -30,7 +30,7 @@
 {{#istrackeduser}}
     {{#overallcomplete}}
         <button
-            class="btn btn-success  {{^normalbutton}}btn-sm{{/normalbutton}} text-nowrap"
+            class="btn btn-subtle-success  {{^normalbutton}}btn-sm{{/normalbutton}} text-nowrap"
             data-action="toggle-manual-completion"
             data-toggletype="manual:undo"
             data-cmid="{{cmid}}"
@@ -50,7 +50,7 @@
     {{/overallcomplete}}
     {{#overallincomplete}}
         <button
-            class="btn btn-outline-secondary  {{^normalbutton}}btn-sm{{/normalbutton}} text-nowrap"
+            class="btn btn-subtle-body  {{^normalbutton}}btn-sm{{/normalbutton}} text-nowrap"
             data-action="toggle-manual-completion"
             data-toggletype="manual:mark-done"
             data-cmid="{{cmid}}"
@@ -71,7 +71,7 @@
 {{/istrackeduser}}
 {{^istrackeduser}}
     <button
-        class="btn btn-outline-secondary  {{^normalbutton}}btn-sm{{/normalbutton}} text-nowrap"
+        class="btn btn-subtle-body {{^normalbutton}}btn-sm{{/normalbutton}} text-nowrap"
         disabled
     >
         {{#str}} completion_manual:markdone, core_course {{/str}}