diff --git a/addons/mail/static/src/composer/composer.xml b/addons/mail/static/src/composer/composer.xml
index b48e4290a4c..8a46cb80c63 100644
--- a/addons/mail/static/src/composer/composer.xml
+++ b/addons/mail/static/src/composer/composer.xml
@@ -27,10 +27,11 @@
             <div class="o-mail-Composer-coreMain d-flex flex-nowrap align-items-start flex-grow-1"
                 t-att-class="{ 'flex-column' : extended }"
             >
-                <div class="d-flex border bg-view flex-grow-1"
+                <div class="d-flex bg-view flex-grow-1"
                     t-att-class="{
-                        'border-end-0 rounded-start-3' : normal,
-                        'rounded-3 align-self-stretch flex-column' : extended,
+                        'border-top border-bottom': compact,
+                        'border border-end-0 rounded-start-3' : normal,
+                        'border rounded-3 align-self-stretch flex-column' : extended,
                     }"
                 >
                     <div class="position-relative flex-grow-1">
diff --git a/addons/mail/static/src/web/chat_window/chat_window.xml b/addons/mail/static/src/web/chat_window/chat_window.xml
index 336c2988431..712377e98cd 100644
--- a/addons/mail/static/src/web/chat_window/chat_window.xml
+++ b/addons/mail/static/src/web/chat_window/chat_window.xml
@@ -46,7 +46,7 @@
                 <i class="fa fa-close"></i>
             </div>
         </div>
-        <div t-if="!props.chatWindow.folded" class="o-mail-ChatWindow-content d-flex flex-column h-100 overflow-auto" t-ref="content">
+        <div t-if="!props.chatWindow.folded" class="o-mail-ChatWindow-content d-flex flex-column h-100 overflow-auto border-start border-end" t-ref="content">
             <t t-if="thread">
                 <CallSettings t-if="state.activeMode === 'in-settings'" thread="thread" className="'flex-grow-1'"/>
                 <ChannelMemberList t-elif="state.activeMode === 'member-list'" thread="thread" className="'o-mail-Discuss-channelMemberList flex-shrink-0 border-start w-100 h-100'"/>