diff --git a/addons/mail/static/src/xml/activity.xml b/addons/mail/static/src/xml/activity.xml
index d399439d79e..a915fccdf2e 100644
--- a/addons/mail/static/src/xml/activity.xml
+++ b/addons/mail/static/src/xml/activity.xml
@@ -58,7 +58,7 @@
                                 </dl>
                             </div>
                         </div>
-                        <div t-if="activity.note" t-attf-class="o_thread_message_#{activity.activity_decoration ? activity.activity_decoration : 'note'} #{activity.activity_decoration ? 'alert alert-' + activity.activity_decoration : ''} small">
+                        <div t-if="activity.note" t-attf-class="o_thread_message_#{activity.activity_decoration ? activity.activity_decoration : 'note'} #{activity.activity_decoration ? 'alert alert-' + activity.activity_decoration : ''}">
                             <t t-raw="activity.note"/>
                         </div>
                         <t t-if="activity.mail_template_ids &amp;&amp; activity.mail_template_ids.length &gt; 0">