diff --git a/group/assign.php b/group/assign.php
index 0218022b696..eca8ae47f54 100644
--- a/group/assign.php
+++ b/group/assign.php
@@ -152,10 +152,10 @@ echo $OUTPUT->header();
           </select></div></td>
       <td id="buttonscell">
         <p class="arrow_button">
-            <input name="add" id="add" type="submit"
+            <input class="btn btn-secondary" name="add" id="add" type="submit"
                    value="<?php echo $OUTPUT->larrow().'&nbsp;'.get_string('add'); ?>"
                    title="<?php print_string('add'); ?>" /><br>
-            <input name="remove" id="remove" type="submit"
+            <input class="btn btn-secondary" name="remove" id="remove" type="submit"
                    value="<?php echo get_string('remove').'&nbsp;'.$OUTPUT->rarrow(); ?>"
                    title="<?php print_string('remove'); ?>" />
         </p>
@@ -173,7 +173,8 @@ echo $OUTPUT->header();
        </td>
     </tr>
     <tr><td colspan="3" id="backcell">
-        <input type="submit" name="cancel" value="<?php print_string('backtogroupings', 'group'); ?>" />
+        <input class="btn btn-secondary" type="submit" name="cancel"
+               value="<?php print_string('backtogroupings', 'group'); ?>" />
     </td></tr>
     </table>
     </div>
diff --git a/group/index.php b/group/index.php
index fb990cca9a1..6571f545d91 100644
--- a/group/index.php
+++ b/group/index.php
@@ -202,20 +202,22 @@ if ($groups) {
 }
 
 echo '</select>'."\n";
-echo '<p><input type="submit" name="act_updatemembers" id="updatemembers" value="'
+echo '<p><input class="btn btn-secondary" type="submit" name="act_updatemembers" id="updatemembers" value="'
         . get_string('showmembersforgroup', 'group') . '" /></p>'."\n";
-echo '<p><input type="submit" '. $showeditgroupsettingsform_disabled . ' name="act_showgroupsettingsform" id="showeditgroupsettingsform" value="'
+echo '<p><input class="btn btn-secondary" type="submit" '. $showeditgroupsettingsform_disabled .
+        ' name="act_showgroupsettingsform" id="showeditgroupsettingsform" value="'
         . get_string('editgroupsettings', 'group') . '" /></p>'."\n";
-echo '<p><input type="submit" '. $deletegroup_disabled . ' name="act_deletegroup" id="deletegroup" value="'
+echo '<p><input class="btn btn-secondary" type="submit" '. $deletegroup_disabled .
+        ' name="act_deletegroup" id="deletegroup" value="'
         . get_string('deleteselectedgroup', 'group') . '" /></p>'."\n";
 
-echo '<p><input type="submit" name="act_showcreateorphangroupform" id="showcreateorphangroupform" value="'
+echo '<p><input class="btn btn-secondary" type="submit" name="act_showcreateorphangroupform" id="showcreateorphangroupform" value="'
         . get_string('creategroup', 'group') . '" /></p>'."\n";
 
-echo '<p><input type="submit" name="act_showautocreategroupsform" id="showautocreategroupsform" value="'
+echo '<p><input class="btn btn-secondary" type="submit" name="act_showautocreategroupsform" id="showautocreategroupsform" value="'
         . get_string('autocreategroups', 'group') . '" /></p>'."\n";
 
-echo '<p><input type="submit" name="act_showimportgroups" id="showimportgroups" value="'
+echo '<p><input class="btn btn-secondary" type="submit" name="act_showimportgroups" id="showimportgroups" value="'
         . get_string('importgroups', 'core_group') . '" /></p>'."\n";
 
 echo html_writer::end_tag('div');
@@ -251,7 +253,7 @@ if (!$atleastonemember) {
 
 echo '</select>'."\n";
 
-echo '<p><input type="submit" ' . $showaddmembersform_disabled . ' name="act_showaddmembersform" '
+echo '<p><input class="btn btn-secondary" type="submit" ' . $showaddmembersform_disabled . ' name="act_showaddmembersform" '
         . 'id="showaddmembersform" value="' . get_string('adduserstogroup', 'group'). '" /></p>'."\n";
 echo html_writer::end_tag('div');
 echo html_writer::end_tag('div');
diff --git a/group/members.php b/group/members.php
index f62f45b80db..3f4e352b152 100644
--- a/group/members.php
+++ b/group/members.php
@@ -152,8 +152,12 @@ if (!empty($groupinforow)) {
           </td>
       <td id='buttonscell'>
         <p class="arrow_button">
-            <input name="add" id="add" type="submit" value="<?php echo $OUTPUT->larrow().'&nbsp;'.get_string('add'); ?>" title="<?php print_string('add'); ?>" /><br />
-            <input name="remove" id="remove" type="submit" value="<?php echo get_string('remove').'&nbsp;'.$OUTPUT->rarrow(); ?>" title="<?php print_string('remove'); ?>" />
+            <input class="btn btn-secondary" name="add" id="add"
+                   type="submit" value="<?php echo $OUTPUT->larrow().'&nbsp;'.get_string('add'); ?>"
+                   title="<?php print_string('add'); ?>" /><br />
+            <input class="btn btn-secondary" name="remove" id="remove"
+                   type="submit" value="<?php echo get_string('remove').'&nbsp;'.$OUTPUT->rarrow(); ?>"
+                   title="<?php print_string('remove'); ?>" />
         </p>
       </td>
       <td id='potentialcell'>
@@ -168,7 +172,8 @@ if (!empty($groupinforow)) {
       </td>
     </tr>
     <tr><td colspan="3" id='backcell'>
-        <input type="submit" name="cancel" value="<?php print_string('backtogroups', 'group'); ?>" />
+        <input class="btn btn-secondary" type="submit" name="cancel"
+               value="<?php print_string('backtogroups', 'group'); ?>" />
     </td></tr>
     </table>
     </div>