diff --git a/addons/mail/static/src/composer/composer.scss b/addons/mail/static/src/composer/composer.scss
index dff2d5de476..4283d5b5a90 100644
--- a/addons/mail/static/src/composer/composer.scss
+++ b/addons/mail/static/src/composer/composer.scss
@@ -32,6 +32,14 @@
     }
 }
 
+.o-mail-Composer-actions button {
+    opacity: 75%;
+    &:hover {
+        background-color: rgba(0, 0, 0, 0.1);
+        opacity: 100%;
+    }
+}
+
 .o-mail-Composer-input {
     padding-top: 10px; // carefully crafted to have the text in the middle in chat window
     padding-bottom: 10px;
diff --git a/addons/mail/static/src/composer/composer.xml b/addons/mail/static/src/composer/composer.xml
index 13631638bfe..371559c2133 100644
--- a/addons/mail/static/src/composer/composer.xml
+++ b/addons/mail/static/src/composer/composer.xml
@@ -31,7 +31,7 @@
                     t-att-class="{
                         'border-top border-bottom': compact and !props.composer.message,
                         'border': props.composer.message,
-                        'border border-end-0 rounded-start-3' : normal,
+                        'border rounded-3' : normal,
                         'border rounded-3 align-self-stretch flex-column' : extended,
                     }"
                 >
@@ -60,33 +60,27 @@
                             disabled="1"
                         />
                     </div>
-                    <div class="d-flex mx-3 bg-view"
+                    <div class="o-mail-Composer-actions d-flex bg-view"
                         t-att-class="{
-                            'px-1' : normal,
-                            'border-top p-1' : extended,
+                            'ms-1' : compact and store.isSmall,
+                            'mx-1 me-2' : compact and !store.isSmall,
+                            'ms-3' : normal,
+                            'mx-3 border-top p-1' : extended,
                         }"
                     >
                         <div class="d-flex flex-grow-1 align-items-center" >
-                            <button class="btn btn-light border-0 fa fa-smile-o rounded-pill" aria-label="Emojis" t-on-click="onClickAddEmoji" t-ref="emoji-picker"/>
+                            <button class="btn border-0 fa fa-smile-o rounded-pill" aria-label="Emojis" t-on-click="onClickAddEmoji" t-ref="emoji-picker"/>
                             <FileUploader t-if="allowUpload" multiUpload="true" onUploaded="(data) => { attachmentUploader.uploadData(data) }">
                                 <t t-set-slot="toggler">
-                                    <button t-att-disabled="!state.active" class="btn btn-light fa fa-paperclip border-0 rounded-pill" title="Attach files" aria-label="Attach files" type="button" t-on-click="onClickAddAttachment"/>
+                                    <button t-att-disabled="!state.active" class="btn fa fa-paperclip border-0 rounded-pill" title="Attach files" aria-label="Attach files" type="button" t-on-click="onClickAddAttachment"/>
                                 </t>
                             </FileUploader>
                         </div>
-                        <button t-if="thread and thread.type === 'chatter'" class="btn btn-light fa fa-expand mx-1 border-0 rounded-pill" title="Full composer" aria-label="Full composer" type="button" t-on-click="onClickFullComposer"/>
+                        <button t-if="thread and thread.type === 'chatter'" class="btn fa fa-expand mx-1 border-0 rounded-pill" title="Full composer" aria-label="Full composer" type="button" t-on-click="onClickFullComposer"/>
                     </div>
+                    <t t-if="!extended" t-call="mail.Composer.sendButton"/>
                 </div>
-                <button t-if="!compact or store.isSmall" class="o-mail-Composer-send btn btn-secondary o-last border-start-0"
-                    t-att-class="{'mt-2': extended, 'rounded-0 rounded-end-3': !extended and !compact, 'align-self-stretch': !extended, 'border border-start-0': env.inDiscussApp}"
-                    t-on-click="sendMessage"
-                    type="button"
-                    t-att-disabled="isSendButtonDisabled"
-                    aria-label="Send"
-                >
-                    <t t-if="store.isSmall"><i class="fa fa-paper-plane-o"/></t>
-                    <t t-else="">Send</t>
-                </button>
+                <t t-if="extended" t-call="mail.Composer.sendButton"/>
             </div>
             <div class="o-mail-Composer-footer overflow-auto">
                 <AttachmentList
@@ -101,6 +95,19 @@
     <NavigableList t-if="suggestion" class="'o-mail-Composer-suggestionList'" t-props="navigableListProps"/>
 </t>
 
+<t t-name="mail.Composer.sendButton" owl="1">
+    <button t-if="!compact or store.isSmall" class="o-mail-Composer-send btn btn-link o-last border-start-0"
+        t-att-class="{'mt-2': extended, 'rounded-0 rounded-end-3': !extended and !compact, 'align-self-stretch': !extended, 'border-start-0': env.inDiscussApp}"
+        t-on-click="sendMessage"
+        type="button"
+        t-att-disabled="isSendButtonDisabled"
+        aria-label="Send"
+    >
+        <t t-if="store.isSmall"><i class="fa fa-paper-plane-o"/></t>
+        <t t-else="">Send</t>
+    </button>
+</t>
+
     <t t-name="mail.Composer.suggestionPartner" owl="1">
         <t t-set="partner" t-value="option.partner"/>
         <ImStatus t-if="partner" persona="partner"/>
diff --git a/addons/mail/static/src/discuss_app/autoresize_input.xml b/addons/mail/static/src/discuss_app/autoresize_input.xml
index 6484a15f4ba..740f682df68 100644
--- a/addons/mail/static/src/discuss_app/autoresize_input.xml
+++ b/addons/mail/static/src/discuss_app/autoresize_input.xml
@@ -3,7 +3,7 @@
 
 <t t-name="mail.AutoresizeInput" owl="1">
     <input
-        class="o-mail-AutoresizeInput text-truncate p-1 border-1 bg-transparent border-transparent"
+        class="o-mail-AutoresizeInput text-truncate p-1 border-1 bg-view border-transparent"
         t-attf-class="{{ props.className }}"
         t-attf-placeholder="{{ props.placeholder }}"
         t-att-disabled="!props.enabled"
diff --git a/addons/mail/static/src/discuss_app/discuss.xml b/addons/mail/static/src/discuss_app/discuss.xml
index 40ed6520a1e..7cb015bf6dc 100644
--- a/addons/mail/static/src/discuss_app/discuss.xml
+++ b/addons/mail/static/src/discuss_app/discuss.xml
@@ -5,10 +5,10 @@
     <div class="o-mail-Discuss d-flex h-100 flex-grow-1 border-top" t-att-class="{ 'flex-column align-items-center bg-view': store.isSmall }" t-ref="root">
         <div t-if="store.isSmall and store.discuss.activeTab === 'mailbox'" class="w-100 border-bottom" t-call="mail.Discuss.mobileTopbar" t-ref="mobileTopbar"/>
         <div t-if="thread and !(store.isSmall and ['chat', 'channel'].includes(store.discuss.activeTab))" class="o-mail-Discuss-content d-flex flex-column h-100 w-100 bg-view overflow-auto" t-ref="content">
-            <div class="o-mail-Discuss-header px-3 bg-100 border-bottom d-flex flex-shrink-0 align-items-center" style="height:46px;">
+            <div class="o-mail-Discuss-header px-3 bg-view border-bottom d-flex flex-shrink-0 align-items-center" style="height:46px;">
                 <div t-if="thread and thread.model === 'discuss.channel'" class="o-mail-Discuss-threadAvatar position-relative align-self-center align-items-center mt-2 mb-2 me-2">
                     <img class="rounded" t-att-src="channelAvatar" alt="Thread Image"/>
-                    <FileUploader t-if="thread.is_editable" acceptedFileExtensions="'.bmp, .jpg, .jpeg, .png, .svg'" showUploadingText="false" multiUpload="false" onUploaded="(data) => this.onFileUploaded(data)">
+                    <FileUploader t-if="thread.is_editable and thread.type !== 'chat'" acceptedFileExtensions="'.bmp, .jpg, .jpeg, .png, .svg'" showUploadingText="false" multiUpload="false" onUploaded="(data) => this.onFileUploaded(data)">
                         <t t-set-slot="toggler">
                             <a href="#" class="position-absolute z-index-1 h-100 w-100 rounded start-0 bottom-0" title="Upload Avatar">
                                 <i class="position-absolute top-50 start-50 fa fa-sm fa-pencil text-white"/>
@@ -63,7 +63,7 @@
                 </div>
             </div>
             <div class="overflow-auto bg-100 d-flex flex-grow-1">
-                <div class="bg-white d-flex flex-column flex-grow-1">
+                <div class="bg-view d-flex flex-column flex-grow-1">
                     <Call t-if="Object.keys(thread.rtcSessions).length > 0" thread="thread"/>
                     <Thread thread="thread" t-key="thread.localId" messageEdition="messageEdition" messageToReplyTo="messageToReplyTo"/>
                     <Composer t-if="thread.type !== 'mailbox' or messageToReplyTo.thread === thread" t-key="thread.localId" composer="thread.composer" autofocus="true" messageEdition="messageEdition" messageToReplyTo="messageToReplyTo" onDiscardCallback="() => messageToReplyTo.cancel()" dropzoneRef="contentRef"/>
diff --git a/addons/mail/static/src/web/discuss_app/sidebar.scss b/addons/mail/static/src/web/discuss_app/sidebar.scss
index 5fe0b705baa..14d0657dc19 100644
--- a/addons/mail/static/src/web/discuss_app/sidebar.scss
+++ b/addons/mail/static/src/web/discuss_app/sidebar.scss
@@ -6,8 +6,12 @@
         height: 15px;
     }
 
-    .o-mail-DiscussCategoryItem:hover .o-mail-DiscussCategoryItem-commands {
-        display: flex !important;
+    .o-mail-DiscussSidebar-item:hover {
+        background-color: $o-gray-300 !important;
+
+        .o-mail-DiscussCategoryItem-commands {
+            display: flex !important;
+        }
     }
 
     .o-mail-DiscussCategory-im-status {
diff --git a/addons/mail/static/src/web/discuss_app/sidebar.xml b/addons/mail/static/src/web/discuss_app/sidebar.xml
index a754ce47c6f..cead8673fef 100644
--- a/addons/mail/static/src/web/discuss_app/sidebar.xml
+++ b/addons/mail/static/src/web/discuss_app/sidebar.xml
@@ -2,7 +2,7 @@
 <templates xml:space="preserve">
 
 <t t-name="mail.DiscussSidebar" owl="1">
-    <div class="o-mail-DiscussSidebar d-flex flex-column overflow-auto flex-shrink-0 h-100 pt-3 border-end bg-light">
+    <div class="o-mail-DiscussSidebar d-flex flex-column overflow-auto flex-shrink-0 h-100 pt-3 border-end bg-view">
         <div class="d-flex justify-content-center">
             <button t-on-click="onClickStartMeeting" class="btn btn-primary rounded" title="Start a meeting">
                 Start a meeting
@@ -32,10 +32,10 @@
 </t>
 
 <t t-name="mail.Mailbox" owl="1">
-    <button class="btn d-flex align-items-center py-1 px-0 border-0 rounded-0 fw-normal text-dark"
+    <button class="o-mail-DiscussSidebar-item btn d-flex align-items-center py-1 px-0 border-0 rounded-0 fw-normal text-reset"
         t-att-class="{
-            'bg-100': mailbox.localId !== store.discuss.threadLocalId,
-            'o-active bg-200': mailbox.localId === store.discuss.threadLocalId,
+            'o-bg-inherit': mailbox.localId !== store.discuss.threadLocalId,
+            'o-active bg-300': mailbox.localId === store.discuss.threadLocalId,
         }"
         t-on-click="(ev) => this.openThread(ev, mailbox)"
     >
@@ -82,10 +82,10 @@
 
 <t t-name="mail.DiscussCategoryItem" owl="1">
     <t t-set="counter" t-value="threadService.getCounter(thread)"/>
-    <button class="o-mail-DiscussCategoryItem btn d-flex align-items-center w-100 px-0 py-2 border-0 text-reset"
+    <button class="o-mail-DiscussCategoryItem o-mail-DiscussSidebar-item btn btn-secondary d-flex align-items-center w-100 px-0 py-2 border-0 text-reset"
         t-att-class="{
-            'bg-100': threadLocalId !== store.discuss.threadLocalId,
-            'o-active bg-200': threadLocalId === store.discuss.threadLocalId,
+            'o-bg-inherit': threadLocalId !== store.discuss.threadLocalId,
+            'o-active bg-300': threadLocalId === store.discuss.threadLocalId,
             'o-unread': thread.message_unread_counter > 0,
         }"
         t-on-click="(ev) => this.openThread(ev, thread)"