diff --git a/addons/mail/static/src/scss/abstract_thread_window.scss b/addons/mail/static/src/scss/abstract_thread_window.scss
index ab6b46d4b9a..9b7238a1fbb 100644
--- a/addons/mail/static/src/scss/abstract_thread_window.scss
+++ b/addons/mail/static/src/scss/abstract_thread_window.scss
@@ -39,8 +39,9 @@ $o-mail-thread-window-zindex: $zindex-modal + 1 !default;
         padding: 8px;
 
         @include media-breakpoint-down(sm) {
+            align-items: center;
             height: $o-mail-chat-header-height;
-            padding-top: 12px;
+            padding: 0;
             border-radius: 0px;
             .o_thread_window_title {
                 font-size: 16px;
@@ -48,7 +49,9 @@ $o-mail-thread-window-zindex: $zindex-modal + 1 !default;
             }
 
             .o_thread_window_close {
-                font-size: 17px;
+                $o-close-font-size: 17px;
+                padding: (($o-mail-chat-header-height - $o-close-font-size) / 2);
+                font-size: $o-close-font-size;
                 color: white;
             }
         }
diff --git a/addons/mail/static/src/xml/abstract_thread_window.xml b/addons/mail/static/src/xml/abstract_thread_window.xml
index 89c45323c7a..9bc83b79242 100644
--- a/addons/mail/static/src/xml/abstract_thread_window.xml
+++ b/addons/mail/static/src/xml/abstract_thread_window.xml
@@ -66,7 +66,7 @@
     -->
     <t t-name="mail.AbstractThreadWindow.HeaderContent">
         <span t-if="widget.isMobile()">
-            <a href="#" class="o_thread_window_close fa fa-1x fa-arrow-left mr4" aria-label="Close chat window" title="Close chat window"/>
+            <a href="#" class="o_thread_window_close fa fa-1x fa-arrow-left" aria-label="Close chat window" title="Close chat window"/>
         </span>
         <span class="o_thread_window_title">
             <t t-if="status" t-call="mail.UserStatus"/>