diff --git src/bp-messages/bp-messages-functions.php src/bp-messages/bp-messages-functions.php
index 08b30d7cc..64980c34b 100644
--- src/bp-messages/bp-messages-functions.php
+++ src/bp-messages/bp-messages-functions.php
@@ -799,3 +799,75 @@ function bp_messages_dismiss_sitewide_notice( $user_id = 0, $notice_id = 0 ) {
 
 	return $retval;
 }
+
+
+/**
+ * Quit message thread(s) for a given user.
+ *
+ * Note that "deleting" a thread for a user means removing it from the user's
+ * message boxes. A thread is not deleted from the database until it's been
+ * "deleted" by all recipients.
+ *
+ * @since 2.7.0 The $user_id parameter was added. Previously the current user
+ *              was always assumed.
+ *
+ * @param int|array $thread_ids Thread ID or array of thread IDs.
+ * @param int       $user_id    ID of the user to delete the threads for. Defaults
+ *                              to the current logged-in user.
+ * @return bool True on success, false on failure.
+ */
+function bp_messages_quit_thread( $thread_ids, $user_id = 0 ) {
+
+	if ( empty( $user_id ) ) {
+		$user_id =
+			bp_displayed_user_id() ?
+			bp_displayed_user_id() :
+			bp_loggedin_user_id();
+	}
+
+	/**
+	 * Fires before specified thread IDs have been deleted.
+	 *
+	 * @since 1.5.0
+	 * @since 2.7.0 The $user_id parameter was added.
+	 *
+	 * @param int|array $thread_ids Thread ID or array of thread IDs to be deleted.
+	 * @param int       $user_id    ID of the user the threads are being deleted for.
+	 */
+	do_action( 'bp_messages_before_quit_thread', $thread_ids, $user_id );
+
+	if ( is_array( $thread_ids ) ) {
+		$error = 0;
+		for ( $i = 0, $count = count( $thread_ids ); $i < $count; ++$i ) {
+			if ( ! BP_Messages_Thread::quit( $thread_ids[ $i ], $user_id ) ) {
+				$error = 1;
+			}
+		}
+
+		if ( ! empty( $error ) ) {
+			return false;
+		}
+
+		/**
+		 * Fires after specified thread IDs have been deleted.
+		 *
+		 * @since 1.0.0
+		 * @since 2.7.0 The $user_id parameter was added.
+		 *
+		 * @param int|array Thread ID or array of thread IDs that were deleted.
+		 * @param int       ID of the user that the threads were deleted for.
+		 */
+		do_action( 'bp_messages_quit_thread', $thread_ids, $user_id );
+
+		return true;
+	} else {
+		if ( ! BP_Messages_Thread::quit( $thread_ids, $user_id ) ) {
+			return false;
+		}
+
+		/** This action is documented in bp-messages/bp-messages-functions.php */
+		do_action( 'bp_messages_quit_thread', $thread_ids, $user_id );
+
+		return true;
+	}
+}
\ No newline at end of file
diff --git src/bp-messages/bp-messages-template.php src/bp-messages/bp-messages-template.php
index 6c100fe98..1c6d0d091 100644
--- src/bp-messages/bp-messages-template.php
+++ src/bp-messages/bp-messages-template.php
@@ -2187,6 +2187,34 @@ function bp_the_thread_delete_link() {
 		 */
 		return apply_filters( 'bp_get_message_thread_delete_link', wp_nonce_url( bp_displayed_user_domain() . bp_get_messages_slug() . '/inbox/delete/' . bp_get_the_thread_id(), 'messages_delete_thread' ) );
 	}
+	
+/**
+ * Output the URL for quit the current thread.
+ *
+ * @since 10.0.0
+ */
+function bp_the_thread_quit_link() {
+	echo esc_url( bp_get_the_thread_quit_link() );
+}
+	/**
+	 * Get the URL for quit the current thread.
+	 *
+	 * @since 10.0.0
+	 *
+	 * @return string URL
+	 */
+	function bp_get_the_thread_quit_link() {
+
+		/**
+		 * Filters the URL for quit the current thread.
+		 *
+		 * @since 1.0.0
+		 *
+		 * @param string $value URL for quit the current thread.
+		 * @param string $value Text indicating action being executed.
+		 */
+		return apply_filters( 'bp_get_message_thread_quit_link', wp_nonce_url( bp_displayed_user_domain() . bp_get_messages_slug() . '/inbox/quit/' . bp_get_the_thread_id(), 'bp_messages_quit_thread' ) );
+	}
 
 /**
  * Output the 'Sent x hours ago' string for the current message.
diff --git src/bp-messages/classes/class-bp-messages-component.php src/bp-messages/classes/class-bp-messages-component.php
index 15f8d0748..d8e530b5e 100644
--- src/bp-messages/classes/class-bp-messages-component.php
+++ src/bp-messages/classes/class-bp-messages-component.php
@@ -102,7 +102,7 @@ class BP_Messages_Component extends BP_Component {
 
 			// Authenticated action variables.
 			if ( is_user_logged_in() && bp_action_variable( 0 ) &&
-				in_array( bp_action_variable( 0 ), array( 'delete', 'read', 'unread', 'bulk-manage', 'bulk-delete' ), true )
+				in_array( bp_action_variable( 0 ), array( 'delete', 'read', 'unread', 'bulk-manage', 'bulk-delete', 'quit' ), true )
 			) {
 				require $this->path . 'bp-messages/actions/' . bp_action_variable( 0 ) . '.php';
 			}
diff --git src/bp-messages/classes/class-bp-messages-thread.php src/bp-messages/classes/class-bp-messages-thread.php
index 9b2dd3601..aca68ee1b 100644
--- src/bp-messages/classes/class-bp-messages-thread.php
+++ src/bp-messages/classes/class-bp-messages-thread.php
@@ -533,6 +533,71 @@ class BP_Messages_Thread {
 
 		return true;
 	}
+	
+	/**
+	 * Mark messages in a thread as deleted or delete all messages in a thread.
+	 *
+	 * Note: All messages in a thread are deleted once every recipient in a thread
+	 * has marked the thread as deleted.
+	 *
+	 * @since 10.0.0
+	 * @since 2.7.0 The $user_id parameter was added. Previously the current user
+	 *              was always assumed.
+	 *
+	 * @global BuddyPress $bp The one true BuddyPress instance.
+	 * @global wpdb $wpdb WordPress database object.
+	 *
+	 * @param int $thread_id The message thread ID.
+	 * @param int $user_id The ID of the user in the thread to mark messages as
+	 *                     deleted for. Defaults to the current logged-in user.
+	 *
+	 * @return bool
+	 */
+	public static function quit( $thread_id = 0, $user_id = 0 ) {
+		global $wpdb;
+		
+		$thread_id = (int) $thread_id;
+		$user_id = (int) $user_id;
+
+		if ( empty( $user_id ) ) {
+			$user_id = bp_loggedin_user_id();
+		}
+
+		/**
+		 * Fires before a message thread is marked as deleted.
+		 *
+		 * @since 2.2.0
+		 * @since 2.7.0 The $user_id parameter was added.
+		 *
+		 * @param int $thread_id ID of the thread being deleted.
+		 * @param int $user_id   ID of the user that the thread is being deleted for.
+		 */
+		do_action( 'bp_messages_thread_before_mark_quit', $thread_id, $user_id );
+
+		$bp = buddypress();
+
+		// Delete from messages recipients
+		$wpdb->query( $wpdb->prepare( "DELETE FROM {$bp->messages->table_name_recipients} WHERE thread_id = %d AND user_id = %d", $thread_id, $user_id ) );
+
+		// Get the message ids in order to pass to the action.
+		$message_ids = $wpdb->get_col( $wpdb->prepare( "SELECT id FROM {$bp->messages->table_name_messages} WHERE thread_id = %d", $thread_id ) );
+
+		
+
+		/**
+		 * Fires after a message thread is either marked as deleted or deleted.
+		 *
+		 * @since 2.2.0
+		 * @since 2.7.0 The $user_id parameter was added.
+		 *
+		 * @param int   $thread_id   ID of the thread being deleted.
+		 * @param array $message_ids IDs of messages being deleted.
+		 * @param int   $user_id     ID of the user the threads were deleted for.
+		 */
+		do_action( 'bp_messages_thread_after_quit', $thread_id, $message_ids, $user_id );
+
+		return true;
+	}
 
 	/**
 	 * Get current message threads for a user.
diff --git src/bp-templates/bp-legacy/buddypress/members/single/messages/single.php src/bp-templates/bp-legacy/buddypress/members/single/messages/single.php
index bc423b740..1ffca47dd 100644
--- src/bp-templates/bp-legacy/buddypress/members/single/messages/single.php
+++ src/bp-templates/bp-legacy/buddypress/members/single/messages/single.php
@@ -49,7 +49,13 @@
 			</span>
 
 			<a class="button confirm" href="<?php bp_the_thread_delete_link(); ?>"><?php _e( 'Delete', 'buddypress' ); ?></a>
-
+			
+			<?php if ( bp_get_thread_recipients_count() > 2 ):?>
+			
+				<a class="button confirm" href="<?php bp_the_thread_quit_link(); ?>"><?php _e( 'Quit Conversation', 'buddypress' ); ?></a>
+				
+			<?php endif;?>
+			
 			<?php
 
 			/**
diff --git src/bp-templates/bp-nouveau/buddypress/common/js-templates/messages/index.php src/bp-templates/bp-nouveau/buddypress/common/js-templates/messages/index.php
index 6b2a5c69f..f92afe6ac 100644
--- src/bp-templates/bp-nouveau/buddypress/common/js-templates/messages/index.php
+++ src/bp-templates/bp-nouveau/buddypress/common/js-templates/messages/index.php
@@ -189,6 +189,10 @@
 						<span class="bp-screen-reader-text"><?php esc_html_e( 'Delete conversation.', 'buddypress' ); ?></span>
 					</button>
 
+					<button type="button" class="message-action-quit bp-tooltip bp-icons" data-bp-action="quit" data-bp-tooltip="<?php esc_attr_e( 'Quit Conversation.', 'buddypress' ); ?>">
+						<span class="bp-screen-reader-text"><?php esc_html_e( 'Quit Conversation.', 'buddypress' ); ?></span>
+					</button>
+
 					<# if ( undefined !== data.star_link ) { #>
 
 						<# if ( false !== data.is_starred ) { #>
@@ -250,6 +254,10 @@
 			<button type="button" class="message-action-delete bp-tooltip bp-icons" data-bp-action="delete" data-bp-tooltip="<?php esc_attr_e( 'Delete conversation.', 'buddypress' ); ?>">
 				<span class="bp-screen-reader-text"><?php esc_html_e( 'Delete conversation.', 'buddypress' ); ?></span>
 			</button>
+
+			<button type="button" class="message-action-quit bp-tooltip bp-icons" data-bp-action="quit" data-bp-tooltip="<?php esc_attr_e( 'Quit Conversation.', 'buddypress' ); ?>">
+				<span class="bp-screen-reader-text"><?php esc_html_e( 'Quit Conversation.', 'buddypress' ); ?></span>
+			</button>
 		</div>
 	</header>
 </script>
diff --git src/bp-templates/bp-nouveau/css/buddypress-rtl.css src/bp-templates/bp-nouveau/css/buddypress-rtl.css
index e8a2edaa1..fdb3dfff9 100644
--- src/bp-templates/bp-nouveau/css/buddypress-rtl.css
+++ src/bp-templates/bp-nouveau/css/buddypress-rtl.css
@@ -69,6 +69,9 @@ body #buddypress select,
 body #buddypress input[type="search"],
 body #buddypress input[type="submit"],
 body #buddypress input[type="reset"] {
+	-webkit-border-radius: 2px;
+	-moz-border-radius: 2px;
+	-ms-border-radius: 2px;
 	border-radius: 2px;
 	background-clip: padding-box;
 }
@@ -79,6 +82,8 @@ body #buddypress .bp-lists blockquote {
 }
 
 body #buddypress .bp-list .action {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
@@ -375,6 +380,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 	.buddypress-wrap.bp-dir-hori-nav:not(.bp-vertical-navs) nav:not(.tabbed-links) {
 		border-bottom: 1px solid #eee;
 		border-top: 1px solid #eee;
+		-webkit-box-shadow: 0 2px 12px 0 #fafafa;
+		-moz-box-shadow: 0 2px 12px 0 #fafafa;
 		box-shadow: 0 2px 12px 0 #fafafa;
 	}
 }
@@ -868,6 +875,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 }
 
 .bp-list {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 	border-top: 1px solid #eaeaea;
 	clear: both;
@@ -1018,6 +1027,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 .activity-list.bp-list .activity-item {
 	background: #fff;
 	border: 1px solid #b7b7b7;
+	-webkit-box-shadow: 0 0 6px #d2d2d2;
+	-moz-box-shadow: 0 0 6px #d2d2d2;
 	box-shadow: 0 0 6px #d2d2d2;
 	margin: 20px 0;
 }
@@ -1038,16 +1049,22 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 @media screen and (min-width: 46.8em) {
 	.friends-request-list li,
 	.membership-requests-list li {
+		display: -webkit-flex;
 		display: -moz-flex;
 		display: -ms-flex;
 		display: -o-flex;
 		display: flex;
+		-webkit-flex-flow: row nowrap;
+		-moz-flex-flow: row nowrap;
+		-ms-flex-flow: row nowrap;
 		-o-flex-flow: row nowrap;
 		flex-flow: row nowrap;
 	}
 	.friends-request-list li .item,
 	.membership-requests-list li .item {
+		-webkit-flex: 1 1 auto;
 		-moz-flex: 1 1 auto;
+		-ms-flex: 1 1 auto;
 		-o-flex: 1 1 auto;
 		flex: 1 1 auto;
 	}
@@ -1103,6 +1120,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 
 .activity-update-form {
 	border: 1px solid #ccc;
+	-webkit-box-shadow: inset 0 0 6px #eee;
+	-moz-box-shadow: inset 0 0 6px #eee;
 	box-shadow: inset 0 0 6px #eee;
 	margin: 15px 0;
 }
@@ -1125,6 +1144,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 
 .activity-update-form #whats-new-textarea textarea {
 	background: #fff;
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 	color: #333;
 	font-family: inherit;
@@ -1136,6 +1157,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 }
 
 .activity-update-form #whats-new-textarea textarea:focus {
+	-webkit-box-shadow: 0 0 6px 0 #d6d6d6;
+	-moz-box-shadow: 0 0 6px 0 #d6d6d6;
 	box-shadow: 0 0 6px 0 #d6d6d6;
 }
 
@@ -1164,7 +1187,13 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 }
 
 .activity-update-form #whats-new-post-in-box #whats-new-post-in-box-items .bp-activity-object {
+	display: -webkit-box;
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
 	padding: 0.2em;
 }
@@ -1512,6 +1541,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 .buddypress-wrap .activity-list .load-newest:focus,
 .buddypress-wrap .activity-list .load-newest:hover {
 	border-color: #e1e1e1;
+	-webkit-box-shadow: 0 0 6px 0 #eaeaea;
+	-moz-box-shadow: 0 0 6px 0 #eaeaea;
 	box-shadow: 0 0 6px 0 #eaeaea;
 }
 
@@ -1577,6 +1608,7 @@ body.activity-permalink .activity-list .activity-comments {
 		top: -20px;
 	}
 	body.activity-permalink .activity-list .activity-avatar img {
+		-webkit-box-shadow: 0 0 0 8px #fff;
 		box-shadow: 0 0 0 8px #fff;
 	}
 	body.activity-permalink .activity-list .activity-content {
@@ -1597,7 +1629,6 @@ body.activity-permalink .activity-list .activity-comments {
 .bp-member-preview-cover img,
 .bp-group-preview-cover img {
 	background: #c5c5c5;
-	-o-object-fit: cover;
 	object-fit: cover;
 	border: 0;
 	display: block;
@@ -1845,6 +1876,8 @@ form.ac-form .ac-reply-content .ac-textarea textarea {
 }
 
 form.ac-form .ac-reply-content .ac-textarea textarea:focus {
+	-webkit-box-shadow: 0 0 6px #d6d6d6;
+	-moz-box-shadow: 0 0 6px #d6d6d6;
 	box-shadow: 0 0 6px #d6d6d6;
 }
 
@@ -1908,6 +1941,9 @@ form.ac-form .ac-reply-content input {
 
 .buddypress-wrap .groups-list li .group-desc {
 	border: 1px solid #eaeaea;
+	-webkit-border-radius: 10px;
+	-moz-border-radius: 10px;
+	-ms-border-radius: 10px;
 	border-radius: 10px;
 	background-clip: padding-box;
 	font-size: 13px;
@@ -1983,6 +2019,9 @@ form.ac-form .ac-reply-content input {
 
 .buddypress-wrap .members-list li .user-update {
 	border: 1px solid #eaeaea;
+	-webkit-border-radius: 10px;
+	-moz-border-radius: 10px;
+	-ms-border-radius: 10px;
 	border-radius: 10px;
 	background-clip: padding-box;
 	color: #737373;
@@ -2032,6 +2071,8 @@ form.ac-form .ac-reply-content input {
 *-------------------------------------------------------------------------------
 */
 .register-page .register-section {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
@@ -2441,6 +2482,8 @@ body.no-js .single-item-header .js-self-profile-button {
 }
 
 .groups-header .moderators-lists img.avatar {
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	float: none;
 	height: 30px;
@@ -2478,6 +2521,8 @@ body.no-js .single-item-header .js-self-profile-button {
 
 .groups-header .desc-wrap .group-description {
 	background: #fafafa;
+	-webkit-box-shadow: inset 0 0 9px #ccc;
+	-moz-box-shadow: inset 0 0 9px #ccc;
 	box-shadow: inset 0 0 9px #ccc;
 	padding: 1em;
 	text-align: right;
@@ -2756,6 +2801,8 @@ body.buddypress.bp-user .buddypress-wrap .member-header-actions * > * {
 }
 
 .buddypress .bp-invites-content ul.item-list li.selected {
+	-webkit-box-shadow: inset 0 0 12px 0 rgba(237, 187, 52, 0.2);
+	-moz-box-shadow: inset 0 0 12px 0 rgba(237, 187, 52, 0.2);
 	box-shadow: inset 0 0 12px 0 rgba(237, 187, 52, 0.2);
 }
 
@@ -2827,6 +2874,8 @@ body.buddypress.bp-user .buddypress-wrap .member-header-actions * > * {
 
 @media screen and (min-width: 46.8em) {
 	.buddypress .bp-invites-content ul.item-list > li {
+		-webkit-box-sizing: border-box;
+		-moz-box-sizing: border-box;
 		box-sizing: border-box;
 		border: 1px solid #eaeaea;
 		float: right;
@@ -2848,7 +2897,9 @@ body.buddypress.bp-user .buddypress-wrap .member-header-actions * > * {
 
 @media screen and (min-width: 46.8em) {
 	:not(.vertical) + .item-body #group-invites-container {
+		display: -ms-grid;
 		display: grid;
+		-ms-grid-columns: 25% auto;
 		grid-template-columns: 25% auto;
 		grid-template-areas: "group-invites-nav group-invites-column";
 	}
@@ -3071,7 +3122,8 @@ body.register .buddypress-wrap .page ul {
 .message-action-star:before,
 .message-action-unstar:before,
 .message-action-view:before,
-.message-action-delete:before {
+.message-action-delete:before,
+.message-action-quit:before {
 	font-family: dashicons;
 	font-size: 18px;
 }
@@ -3094,6 +3146,10 @@ body.register .buddypress-wrap .page ul {
 	content: "\f153";
 }
 
+.message-action-quit:before {
+	content: "\f14a";
+}
+
 .message-action-delete:hover:before {
 	color: #a00;
 }
@@ -3107,6 +3163,8 @@ body.register .buddypress-wrap .page ul {
 }
 
 .bp-messages-content .avatar {
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 }
 
@@ -3137,10 +3195,14 @@ body.register .buddypress-wrap .page ul {
 
 #message-threads li {
 	border-bottom: 1px solid #eaeaea;
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: row nowrap;
+	-moz-flex-flow: row nowrap;
+	-ms-flex-flow: row nowrap;
 	-o-flex-flow: row nowrap;
 	flex-flow: row nowrap;
 	margin: 0;
@@ -3149,16 +3211,26 @@ body.register .buddypress-wrap .page ul {
 }
 
 #message-threads li .thread-cb {
+	display: -webkit-box;
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
+	-webkit-flex: 1 2 5%;
 	-moz-flex: 1 2 5%;
+	-ms-flex: 1 2 5%;
 	-o-flex: 1 2 5%;
 	flex: 1 2 5%;
 }
 
 #message-threads li .thread-from,
 #message-threads li .thread-to {
+	-webkit-flex: 1 2 20%;
 	-moz-flex: 1 2 20%;
+	-ms-flex: 1 2 20%;
 	-o-flex: 1 2 20%;
 	flex: 1 2 20%;
 }
@@ -3184,13 +3256,17 @@ body.register .buddypress-wrap .page ul {
 }
 
 #message-threads li .thread-content {
+	-webkit-flex: 1 2 60%;
 	-moz-flex: 1 2 60%;
+	-ms-flex: 1 2 60%;
 	-o-flex: 1 2 60%;
 	flex: 1 2 60%;
 }
 
 #message-threads li .thread-date {
+	-webkit-flex: 1 2 15%;
 	-moz-flex: 1 2 15%;
+	-ms-flex: 1 2 15%;
 	-o-flex: 1 2 15%;
 	flex: 1 2 15%;
 }
@@ -3292,6 +3368,8 @@ body.register .buddypress-wrap .page ul {
 
 .bp-messages-content #bp-message-thread-list .message-metadata {
 	border-bottom: 1px solid #ccc;
+	-webkit-box-shadow: 2px 1px 9px 0 #eee;
+	-moz-box-shadow: 2px 1px 9px 0 #eee;
 	box-shadow: 2px 1px 9px 0 #eee;
 	display: table;
 	padding: 0.2em;
@@ -3535,6 +3613,8 @@ body.buddypress.settings.data #buddypress.buddypress-wrap .item-body p a {
 .buddypress-wrap input[type="url"]:focus,
 .buddypress-wrap input[type="tel"]:focus,
 .buddypress-wrap input[type="password"]:focus {
+	-webkit-box-shadow: 0 0 8px #eaeaea;
+	-moz-box-shadow: 0 0 8px #eaeaea;
 	box-shadow: 0 0 8px #eaeaea;
 }
 
@@ -3774,6 +3854,7 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 }
 
 .buddypress-wrap .select-wrap select {
+	-moz-appearance: none;
 	-webkit-appearance: none;
 	-o-appearance: none;
 	appearance: none;
@@ -3868,6 +3949,9 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap form#group-members-search button[type="submit"] {
 	background: none;
 	border: 0;
+	-webkit-border-radius: 0;
+	-moz-border-radius: 0;
+	-ms-border-radius: 0;
 	border-radius: 0;
 	background-clip: padding-box;
 }
@@ -4144,7 +4228,12 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 }
 
 .center-vert {
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
 }
 
@@ -4258,6 +4347,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress .buddypress-wrap input.text-button {
 	background: none;
 	border: 0;
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	color: #767676;
 }
@@ -4353,8 +4444,13 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 
 .buddypress #buddypress .create-button a {
 	border: 1px solid #ccc;
+	-webkit-border-radius: 5px;
+	-moz-border-radius: 5px;
+	-ms-border-radius: 5px;
 	border-radius: 5px;
 	background-clip: padding-box;
+	-webkit-box-shadow: inset 0 0 6px 0 #eaeaea;
+	-moz-box-shadow: inset 0 0 6px 0 #eaeaea;
 	box-shadow: inset 0 0 6px 0 #eaeaea;
 	margin: 0.2em 0;
 	width: auto;
@@ -4363,6 +4459,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress #buddypress .create-button a:focus, .buddypress #buddypress .create-button a:hover {
 	background: none;
 	border-color: #ccc;
+	-webkit-box-shadow: inset 0 0 12px 0 #eaeaea;
+	-moz-box-shadow: inset 0 0 12px 0 #eaeaea;
 	box-shadow: inset 0 0 12px 0 #eaeaea;
 }
 
@@ -4384,6 +4482,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress #buddypress.bp-dir-hori-nav .create-button a:hover {
 	background: none;
 	border: 0;
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	margin: 0;
 }
@@ -4484,17 +4584,26 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap #group-create-body .bp-cover-image-status p.warning {
 	background: #0b80a4;
 	border: 0;
+	-webkit-box-shadow: 0 0 3px 0 rgba(0, 0, 0, 0.2);
+	-moz-box-shadow: 0 0 3px 0 rgba(0, 0, 0, 0.2);
 	box-shadow: 0 0 3px 0 rgba(0, 0, 0, 0.2);
 	color: #fff;
 }
 
 .buddypress-wrap .bp-feedback:not(.custom-homepage-info) {
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: row nowrap;
+	-moz-flex-flow: row nowrap;
+	-ms-flex-flow: row nowrap;
 	-o-flex-flow: row nowrap;
 	flex-flow: row nowrap;
+	-ms-flex-align: stretch;
+	-webkit-align-items: stretch;
+	-webkit-box-align: stretch;
 	align-items: stretch;
 	align-items: center;
 }
@@ -4502,6 +4611,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap .bp-feedback {
 	background: #fff;
 	color: #807f7f;
+	-webkit-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
+	-moz-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	color: #737373;
 	margin: 10px 0;
@@ -4580,7 +4691,13 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap .bp-feedback.loading .bp-icon,
 .buddypress-wrap .bp-feedback.success .bp-icon,
 .buddypress-wrap .bp-feedback.updated .bp-icon {
+	display: -webkit-box;
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
 	align-self: stretch;
 }
@@ -4703,6 +4820,8 @@ body.create-blog #buddypress .error,
 body.create-blog #buddypress .success {
 	background: #fff;
 	color: #807f7f;
+	-webkit-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
+	-moz-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	color: #737373;
 	padding: 10px 15px;
@@ -4822,10 +4941,14 @@ body.create-blog #buddypress .success {
 }
 
 .buddypress.widget .avatar-block {
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: row wrap;
+	-moz-flex-flow: row wrap;
+	-ms-flex-flow: row wrap;
 	-o-flex-flow: row wrap;
 	flex-flow: row wrap;
 }
@@ -4872,10 +4995,14 @@ body.create-blog #buddypress .success {
 .buddypress-wrap .buddypress.widget ul#friends-list,
 .buddypress-wrap .buddypress.widget ul#groups-list,
 .buddypress-wrap .buddypress.widget ul#members-list {
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: column nowrap;
+	-moz-flex-flow: column nowrap;
+	-ms-flex-flow: column nowrap;
 	-o-flex-flow: column nowrap;
 	flex-flow: column nowrap;
 }
@@ -4884,10 +5011,14 @@ body.create-blog #buddypress .success {
 	.buddypress-wrap .buddypress.widget ul#friends-list,
 	.buddypress-wrap .buddypress.widget ul#groups-list,
 	.buddypress-wrap .buddypress.widget ul#members-list {
+		display: -webkit-flex;
 		display: -moz-flex;
 		display: -ms-flex;
 		display: -o-flex;
 		display: flex;
+		-webkit-flex-flow: row wrap;
+		-moz-flex-flow: row wrap;
+		-ms-flex-flow: row wrap;
 		-o-flex-flow: row wrap;
 		flex-flow: row wrap;
 	}
@@ -4897,8 +5028,13 @@ body.create-blog #buddypress .success {
 .buddypress-wrap .buddypress.widget ul#groups-list li,
 .buddypress-wrap .buddypress.widget ul#members-list li {
 	border: 1px solid #eee;
+	-ms-flex-align: stretch;
+	-webkit-align-items: stretch;
+	-webkit-box-align: stretch;
 	align-items: stretch;
+	-webkit-flex: 1 1 46%;
 	-moz-flex: 1 1 46%;
+	-ms-flex: 1 1 46%;
 	-o-flex: 1 1 46%;
 	flex: 1 1 46%;
 	margin: 2%;
@@ -4908,7 +5044,9 @@ body.create-blog #buddypress .success {
 	.buddypress-wrap .buddypress.widget ul#friends-list li,
 	.buddypress-wrap .buddypress.widget ul#groups-list li,
 	.buddypress-wrap .buddypress.widget ul#members-list li {
+		-webkit-flex: 0 1 20%;
 		-moz-flex: 0 1 20%;
+		-ms-flex: 0 1 20%;
 		-o-flex: 0 1 20%;
 		flex: 0 1 20%;
 	}
@@ -4944,7 +5082,9 @@ body.create-blog #buddypress .success {
 	.buddypress-wrap .buddypress.widget ul#friends-list li,
 	.buddypress-wrap .buddypress.widget ul#groups-list li,
 	.buddypress-wrap .buddypress.widget ul#members-list li {
+		-webkit-flex: 0 1 auto;
 		-moz-flex: 0 1 auto;
+		-ms-flex: 0 1 auto;
 		-o-flex: 0 1 auto;
 		flex: 0 1 auto;
 		margin: 10px 2% 1%;
@@ -4972,17 +5112,47 @@ body.create-blog #buddypress .success {
 
 .buddypress-wrap a.loading,
 .buddypress-wrap input.loading {
+	-moz-animation: loader-pulsate 0.5s infinite ease-in-out alternate;
+	-webkit-animation: loader-pulsate 0.5s infinite ease-in-out alternate;
 	animation: loader-pulsate 0.5s infinite ease-in-out alternate;
 	border-color: #aaa;
 }
 
+@-webkit-keyframes loader-pulsate {
+	from {
+		border-color: #aaa;
+		-webkit-box-shadow: 0 0 6px #ccc;
+		box-shadow: 0 0 6px #ccc;
+	}
+	to {
+		border-color: #ccc;
+		-webkit-box-shadow: 0 0 6px #f8f8f8;
+		box-shadow: 0 0 6px #f8f8f8;
+	}
+}
+
+@-moz-keyframes loader-pulsate {
+	from {
+		border-color: #aaa;
+		-moz-box-shadow: 0 0 6px #ccc;
+		box-shadow: 0 0 6px #ccc;
+	}
+	to {
+		border-color: #ccc;
+		-moz-box-shadow: 0 0 6px #f8f8f8;
+		box-shadow: 0 0 6px #f8f8f8;
+	}
+}
+
 @keyframes loader-pulsate {
 	from {
 		border-color: #aaa;
+		-moz-box-shadow: 0 0 6px #ccc;
 		box-shadow: 0 0 6px #ccc;
 	}
 	to {
 		border-color: #ccc;
+		-moz-box-shadow: 0 0 6px #f8f8f8;
 		box-shadow: 0 0 6px #f8f8f8;
 	}
 }
@@ -5001,6 +5171,8 @@ body.create-blog #buddypress .success {
 	display: none;
 	opacity: 0;
 	position: absolute;
+	-webkit-transform: translate3d(0, 0, 0);
+	-ms-transform: translate3d(0, 0, 0);
 	transform: translate3d(0, 0, 0);
 	visibility: hidden;
 }
@@ -5021,6 +5193,8 @@ body.create-blog #buddypress .success {
 	pointer-events: none;
 	text-shadow: none;
 	text-transform: none;
+	-webkit-transition: all 1.5s ease;
+	-ms-transition: all 1.5s ease;
 	transition: all 1.5s ease;
 	white-space: nowrap;
 	word-wrap: break-word;
@@ -5044,11 +5218,15 @@ body.create-blog #buddypress .success {
 	right: 50%;
 	margin-top: 7px;
 	top: 110%;
+	-webkit-transform: translate(50%, 0);
+	-ms-transform: translate(50%, 0);
 	transform: translate(50%, 0);
 }
 
 .user-list .bp-tooltip:after {
 	right: 0;
+	-webkit-transform: translate(0, 0);
+	-ms-transform: translate(0, 0);
 	transform: translate(0, 0);
 }
 
@@ -5056,6 +5234,8 @@ body.create-blog #buddypress .success {
 	.user-list .bp-tooltip:after {
 		right: auto;
 		left: 0;
+		-webkit-transform: translate(0, 0);
+		-ms-transform: translate(0, 0);
 		transform: translate(0, 0);
 	}
 }
@@ -5066,6 +5246,8 @@ body.create-blog #buddypress .success {
 .notification-actions .bp-tooltip:after,
 .participants-list .bp-tooltip:after {
 	right: 0;
+	-webkit-transform: translate(0, 0);
+	-ms-transform: translate(0, 0);
 	transform: translate(0, 0);
 }
 
@@ -5074,6 +5256,8 @@ body.create-blog #buddypress .success {
 .single-message-thread-header .actions .bp-tooltip:after {
 	right: auto;
 	left: 0;
+	-webkit-transform: translate(0, 0);
+	-ms-transform: translate(0, 0);
 	transform: translate(0, 0);
 }
 
@@ -5089,11 +5273,15 @@ body.create-blog #buddypress .success {
 */
 #item-body,
 .single-screen-navs {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
 .grid > li,
 .grid > li .generic-button a {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
diff --git src/bp-templates/bp-nouveau/css/buddypress.css src/bp-templates/bp-nouveau/css/buddypress.css
index be35e509e..64f683dd9 100644
--- src/bp-templates/bp-nouveau/css/buddypress.css
+++ src/bp-templates/bp-nouveau/css/buddypress.css
@@ -69,6 +69,9 @@ body #buddypress select,
 body #buddypress input[type="search"],
 body #buddypress input[type="submit"],
 body #buddypress input[type="reset"] {
+	-webkit-border-radius: 2px;
+	-moz-border-radius: 2px;
+	-ms-border-radius: 2px;
 	border-radius: 2px;
 	background-clip: padding-box;
 }
@@ -79,6 +82,8 @@ body #buddypress .bp-lists blockquote {
 }
 
 body #buddypress .bp-list .action {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
@@ -375,6 +380,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 	.buddypress-wrap.bp-dir-hori-nav:not(.bp-vertical-navs) nav:not(.tabbed-links) {
 		border-bottom: 1px solid #eee;
 		border-top: 1px solid #eee;
+		-webkit-box-shadow: 0 2px 12px 0 #fafafa;
+		-moz-box-shadow: 0 2px 12px 0 #fafafa;
 		box-shadow: 0 2px 12px 0 #fafafa;
 	}
 }
@@ -868,6 +875,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 }
 
 .bp-list {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 	border-top: 1px solid #eaeaea;
 	clear: both;
@@ -1018,6 +1027,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 .activity-list.bp-list .activity-item {
 	background: #fff;
 	border: 1px solid #b7b7b7;
+	-webkit-box-shadow: 0 0 6px #d2d2d2;
+	-moz-box-shadow: 0 0 6px #d2d2d2;
 	box-shadow: 0 0 6px #d2d2d2;
 	margin: 20px 0;
 }
@@ -1038,16 +1049,22 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 @media screen and (min-width: 46.8em) {
 	.friends-request-list li,
 	.membership-requests-list li {
+		display: -webkit-flex;
 		display: -moz-flex;
 		display: -ms-flex;
 		display: -o-flex;
 		display: flex;
+		-webkit-flex-flow: row nowrap;
+		-moz-flex-flow: row nowrap;
+		-ms-flex-flow: row nowrap;
 		-o-flex-flow: row nowrap;
 		flex-flow: row nowrap;
 	}
 	.friends-request-list li .item,
 	.membership-requests-list li .item {
+		-webkit-flex: 1 1 auto;
 		-moz-flex: 1 1 auto;
+		-ms-flex: 1 1 auto;
 		-o-flex: 1 1 auto;
 		flex: 1 1 auto;
 	}
@@ -1103,6 +1120,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 
 .activity-update-form {
 	border: 1px solid #ccc;
+	-webkit-box-shadow: inset 0 0 6px #eee;
+	-moz-box-shadow: inset 0 0 6px #eee;
 	box-shadow: inset 0 0 6px #eee;
 	margin: 15px 0;
 }
@@ -1125,6 +1144,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 
 .activity-update-form #whats-new-textarea textarea {
 	background: #fff;
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 	color: #333;
 	font-family: inherit;
@@ -1136,6 +1157,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 }
 
 .activity-update-form #whats-new-textarea textarea:focus {
+	-webkit-box-shadow: 0 0 6px 0 #d6d6d6;
+	-moz-box-shadow: 0 0 6px 0 #d6d6d6;
 	box-shadow: 0 0 6px 0 #d6d6d6;
 }
 
@@ -1164,7 +1187,13 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 }
 
 .activity-update-form #whats-new-post-in-box #whats-new-post-in-box-items .bp-activity-object {
+	display: -webkit-box;
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
 	padding: 0.2em;
 }
@@ -1512,6 +1541,8 @@ body.buddypress article.page > .entry-header:not(.alignwide):not(.alignfull) .en
 .buddypress-wrap .activity-list .load-newest:focus,
 .buddypress-wrap .activity-list .load-newest:hover {
 	border-color: #e1e1e1;
+	-webkit-box-shadow: 0 0 6px 0 #eaeaea;
+	-moz-box-shadow: 0 0 6px 0 #eaeaea;
 	box-shadow: 0 0 6px 0 #eaeaea;
 }
 
@@ -1577,6 +1608,7 @@ body.activity-permalink .activity-list .activity-comments {
 		top: -20px;
 	}
 	body.activity-permalink .activity-list .activity-avatar img {
+		-webkit-box-shadow: 0 0 0 8px #fff;
 		box-shadow: 0 0 0 8px #fff;
 	}
 	body.activity-permalink .activity-list .activity-content {
@@ -1597,7 +1629,6 @@ body.activity-permalink .activity-list .activity-comments {
 .bp-member-preview-cover img,
 .bp-group-preview-cover img {
 	background: #c5c5c5;
-	-o-object-fit: cover;
 	object-fit: cover;
 	border: 0;
 	display: block;
@@ -1845,6 +1876,8 @@ form.ac-form .ac-reply-content .ac-textarea textarea {
 }
 
 form.ac-form .ac-reply-content .ac-textarea textarea:focus {
+	-webkit-box-shadow: 0 0 6px #d6d6d6;
+	-moz-box-shadow: 0 0 6px #d6d6d6;
 	box-shadow: 0 0 6px #d6d6d6;
 }
 
@@ -1908,6 +1941,9 @@ form.ac-form .ac-reply-content input {
 
 .buddypress-wrap .groups-list li .group-desc {
 	border: 1px solid #eaeaea;
+	-webkit-border-radius: 10px;
+	-moz-border-radius: 10px;
+	-ms-border-radius: 10px;
 	border-radius: 10px;
 	background-clip: padding-box;
 	font-size: 13px;
@@ -1983,6 +2019,9 @@ form.ac-form .ac-reply-content input {
 
 .buddypress-wrap .members-list li .user-update {
 	border: 1px solid #eaeaea;
+	-webkit-border-radius: 10px;
+	-moz-border-radius: 10px;
+	-ms-border-radius: 10px;
 	border-radius: 10px;
 	background-clip: padding-box;
 	color: #737373;
@@ -2032,6 +2071,8 @@ form.ac-form .ac-reply-content input {
 *-------------------------------------------------------------------------------
 */
 .register-page .register-section {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
@@ -2441,6 +2482,8 @@ body.no-js .single-item-header .js-self-profile-button {
 }
 
 .groups-header .moderators-lists img.avatar {
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	float: none;
 	height: 30px;
@@ -2478,6 +2521,8 @@ body.no-js .single-item-header .js-self-profile-button {
 
 .groups-header .desc-wrap .group-description {
 	background: #fafafa;
+	-webkit-box-shadow: inset 0 0 9px #ccc;
+	-moz-box-shadow: inset 0 0 9px #ccc;
 	box-shadow: inset 0 0 9px #ccc;
 	padding: 1em;
 	text-align: left;
@@ -2756,6 +2801,8 @@ body.buddypress.bp-user .buddypress-wrap .member-header-actions * > * {
 }
 
 .buddypress .bp-invites-content ul.item-list li.selected {
+	-webkit-box-shadow: inset 0 0 12px 0 rgba(237, 187, 52, 0.2);
+	-moz-box-shadow: inset 0 0 12px 0 rgba(237, 187, 52, 0.2);
 	box-shadow: inset 0 0 12px 0 rgba(237, 187, 52, 0.2);
 }
 
@@ -2827,6 +2874,8 @@ body.buddypress.bp-user .buddypress-wrap .member-header-actions * > * {
 
 @media screen and (min-width: 46.8em) {
 	.buddypress .bp-invites-content ul.item-list > li {
+		-webkit-box-sizing: border-box;
+		-moz-box-sizing: border-box;
 		box-sizing: border-box;
 		border: 1px solid #eaeaea;
 		float: left;
@@ -2848,7 +2897,9 @@ body.buddypress.bp-user .buddypress-wrap .member-header-actions * > * {
 
 @media screen and (min-width: 46.8em) {
 	:not(.vertical) + .item-body #group-invites-container {
+		display: -ms-grid;
 		display: grid;
+		-ms-grid-columns: 25% auto;
 		grid-template-columns: 25% auto;
 		grid-template-areas: "group-invites-nav group-invites-column";
 	}
@@ -3071,7 +3122,8 @@ body.register .buddypress-wrap .page ul {
 .message-action-star:before,
 .message-action-unstar:before,
 .message-action-view:before,
-.message-action-delete:before {
+.message-action-delete:before,
+.message-action-quit:before {
 	font-family: dashicons;
 	font-size: 18px;
 }
@@ -3094,6 +3146,10 @@ body.register .buddypress-wrap .page ul {
 	content: "\f153";
 }
 
+.message-action-quit:before {
+	content: "\f14a";
+}
+
 .message-action-delete:hover:before {
 	color: #a00;
 }
@@ -3107,6 +3163,8 @@ body.register .buddypress-wrap .page ul {
 }
 
 .bp-messages-content .avatar {
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 }
 
@@ -3137,10 +3195,14 @@ body.register .buddypress-wrap .page ul {
 
 #message-threads li {
 	border-bottom: 1px solid #eaeaea;
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: row nowrap;
+	-moz-flex-flow: row nowrap;
+	-ms-flex-flow: row nowrap;
 	-o-flex-flow: row nowrap;
 	flex-flow: row nowrap;
 	margin: 0;
@@ -3149,16 +3211,26 @@ body.register .buddypress-wrap .page ul {
 }
 
 #message-threads li .thread-cb {
+	display: -webkit-box;
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
+	-webkit-flex: 1 2 5%;
 	-moz-flex: 1 2 5%;
+	-ms-flex: 1 2 5%;
 	-o-flex: 1 2 5%;
 	flex: 1 2 5%;
 }
 
 #message-threads li .thread-from,
 #message-threads li .thread-to {
+	-webkit-flex: 1 2 20%;
 	-moz-flex: 1 2 20%;
+	-ms-flex: 1 2 20%;
 	-o-flex: 1 2 20%;
 	flex: 1 2 20%;
 }
@@ -3184,13 +3256,17 @@ body.register .buddypress-wrap .page ul {
 }
 
 #message-threads li .thread-content {
+	-webkit-flex: 1 2 60%;
 	-moz-flex: 1 2 60%;
+	-ms-flex: 1 2 60%;
 	-o-flex: 1 2 60%;
 	flex: 1 2 60%;
 }
 
 #message-threads li .thread-date {
+	-webkit-flex: 1 2 15%;
 	-moz-flex: 1 2 15%;
+	-ms-flex: 1 2 15%;
 	-o-flex: 1 2 15%;
 	flex: 1 2 15%;
 }
@@ -3292,6 +3368,8 @@ body.register .buddypress-wrap .page ul {
 
 .bp-messages-content #bp-message-thread-list .message-metadata {
 	border-bottom: 1px solid #ccc;
+	-webkit-box-shadow: -2px 1px 9px 0 #eee;
+	-moz-box-shadow: -2px 1px 9px 0 #eee;
 	box-shadow: -2px 1px 9px 0 #eee;
 	display: table;
 	padding: 0.2em;
@@ -3535,6 +3613,8 @@ body.buddypress.settings.data #buddypress.buddypress-wrap .item-body p a {
 .buddypress-wrap input[type="url"]:focus,
 .buddypress-wrap input[type="tel"]:focus,
 .buddypress-wrap input[type="password"]:focus {
+	-webkit-box-shadow: 0 0 8px #eaeaea;
+	-moz-box-shadow: 0 0 8px #eaeaea;
 	box-shadow: 0 0 8px #eaeaea;
 }
 
@@ -3774,6 +3854,7 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 }
 
 .buddypress-wrap .select-wrap select {
+	-moz-appearance: none;
 	-webkit-appearance: none;
 	-o-appearance: none;
 	appearance: none;
@@ -3868,6 +3949,9 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap form#group-members-search button[type="submit"] {
 	background: none;
 	border: 0;
+	-webkit-border-radius: 0;
+	-moz-border-radius: 0;
+	-ms-border-radius: 0;
 	border-radius: 0;
 	background-clip: padding-box;
 }
@@ -4144,7 +4228,12 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 }
 
 .center-vert {
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
 }
 
@@ -4258,6 +4347,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress .buddypress-wrap input.text-button {
 	background: none;
 	border: 0;
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	color: #767676;
 }
@@ -4353,8 +4444,13 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 
 .buddypress #buddypress .create-button a {
 	border: 1px solid #ccc;
+	-webkit-border-radius: 5px;
+	-moz-border-radius: 5px;
+	-ms-border-radius: 5px;
 	border-radius: 5px;
 	background-clip: padding-box;
+	-webkit-box-shadow: inset 0 0 6px 0 #eaeaea;
+	-moz-box-shadow: inset 0 0 6px 0 #eaeaea;
 	box-shadow: inset 0 0 6px 0 #eaeaea;
 	margin: 0.2em 0;
 	width: auto;
@@ -4363,6 +4459,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress #buddypress .create-button a:focus, .buddypress #buddypress .create-button a:hover {
 	background: none;
 	border-color: #ccc;
+	-webkit-box-shadow: inset 0 0 12px 0 #eaeaea;
+	-moz-box-shadow: inset 0 0 12px 0 #eaeaea;
 	box-shadow: inset 0 0 12px 0 #eaeaea;
 }
 
@@ -4384,6 +4482,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress #buddypress.bp-dir-hori-nav .create-button a:hover {
 	background: none;
 	border: 0;
+	-moz-box-shadow: none;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	margin: 0;
 }
@@ -4484,17 +4584,26 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap #group-create-body .bp-cover-image-status p.warning {
 	background: #0b80a4;
 	border: 0;
+	-webkit-box-shadow: 0 0 3px 0 rgba(0, 0, 0, 0.2);
+	-moz-box-shadow: 0 0 3px 0 rgba(0, 0, 0, 0.2);
 	box-shadow: 0 0 3px 0 rgba(0, 0, 0, 0.2);
 	color: #fff;
 }
 
 .buddypress-wrap .bp-feedback:not(.custom-homepage-info) {
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: row nowrap;
+	-moz-flex-flow: row nowrap;
+	-ms-flex-flow: row nowrap;
 	-o-flex-flow: row nowrap;
 	flex-flow: row nowrap;
+	-ms-flex-align: stretch;
+	-webkit-align-items: stretch;
+	-webkit-box-align: stretch;
 	align-items: stretch;
 	align-items: center;
 }
@@ -4502,6 +4611,8 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap .bp-feedback {
 	background: #fff;
 	color: #807f7f;
+	-webkit-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
+	-moz-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	color: #737373;
 	margin: 10px 0;
@@ -4580,7 +4691,13 @@ body.no-js .buddypress #messages-bulk-management #select-all-messages {
 .buddypress-wrap .bp-feedback.loading .bp-icon,
 .buddypress-wrap .bp-feedback.success .bp-icon,
 .buddypress-wrap .bp-feedback.updated .bp-icon {
+	display: -webkit-box;
+	display: -ms-flexbox;
+	display: -webkit-flex;
 	display: flex;
+	-ms-flex-align: center;
+	-webkit-align-items: center;
+	-webkit-box-align: center;
 	align-items: center;
 	align-self: stretch;
 }
@@ -4703,6 +4820,8 @@ body.create-blog #buddypress .error,
 body.create-blog #buddypress .success {
 	background: #fff;
 	color: #807f7f;
+	-webkit-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
+	-moz-box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	box-shadow: 0 1px 1px 1px rgba(0, 0, 0, 0.1);
 	color: #737373;
 	padding: 10px 15px;
@@ -4822,10 +4941,14 @@ body.create-blog #buddypress .success {
 }
 
 .buddypress.widget .avatar-block {
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: row wrap;
+	-moz-flex-flow: row wrap;
+	-ms-flex-flow: row wrap;
 	-o-flex-flow: row wrap;
 	flex-flow: row wrap;
 }
@@ -4872,10 +4995,14 @@ body.create-blog #buddypress .success {
 .buddypress-wrap .buddypress.widget ul#friends-list,
 .buddypress-wrap .buddypress.widget ul#groups-list,
 .buddypress-wrap .buddypress.widget ul#members-list {
+	display: -webkit-flex;
 	display: -moz-flex;
 	display: -ms-flex;
 	display: -o-flex;
 	display: flex;
+	-webkit-flex-flow: column nowrap;
+	-moz-flex-flow: column nowrap;
+	-ms-flex-flow: column nowrap;
 	-o-flex-flow: column nowrap;
 	flex-flow: column nowrap;
 }
@@ -4884,10 +5011,14 @@ body.create-blog #buddypress .success {
 	.buddypress-wrap .buddypress.widget ul#friends-list,
 	.buddypress-wrap .buddypress.widget ul#groups-list,
 	.buddypress-wrap .buddypress.widget ul#members-list {
+		display: -webkit-flex;
 		display: -moz-flex;
 		display: -ms-flex;
 		display: -o-flex;
 		display: flex;
+		-webkit-flex-flow: row wrap;
+		-moz-flex-flow: row wrap;
+		-ms-flex-flow: row wrap;
 		-o-flex-flow: row wrap;
 		flex-flow: row wrap;
 	}
@@ -4897,8 +5028,13 @@ body.create-blog #buddypress .success {
 .buddypress-wrap .buddypress.widget ul#groups-list li,
 .buddypress-wrap .buddypress.widget ul#members-list li {
 	border: 1px solid #eee;
+	-ms-flex-align: stretch;
+	-webkit-align-items: stretch;
+	-webkit-box-align: stretch;
 	align-items: stretch;
+	-webkit-flex: 1 1 46%;
 	-moz-flex: 1 1 46%;
+	-ms-flex: 1 1 46%;
 	-o-flex: 1 1 46%;
 	flex: 1 1 46%;
 	margin: 2%;
@@ -4908,7 +5044,9 @@ body.create-blog #buddypress .success {
 	.buddypress-wrap .buddypress.widget ul#friends-list li,
 	.buddypress-wrap .buddypress.widget ul#groups-list li,
 	.buddypress-wrap .buddypress.widget ul#members-list li {
+		-webkit-flex: 0 1 20%;
 		-moz-flex: 0 1 20%;
+		-ms-flex: 0 1 20%;
 		-o-flex: 0 1 20%;
 		flex: 0 1 20%;
 	}
@@ -4944,7 +5082,9 @@ body.create-blog #buddypress .success {
 	.buddypress-wrap .buddypress.widget ul#friends-list li,
 	.buddypress-wrap .buddypress.widget ul#groups-list li,
 	.buddypress-wrap .buddypress.widget ul#members-list li {
+		-webkit-flex: 0 1 auto;
 		-moz-flex: 0 1 auto;
+		-ms-flex: 0 1 auto;
 		-o-flex: 0 1 auto;
 		flex: 0 1 auto;
 		margin: 10px 2% 1%;
@@ -4972,17 +5112,47 @@ body.create-blog #buddypress .success {
 
 .buddypress-wrap a.loading,
 .buddypress-wrap input.loading {
+	-moz-animation: loader-pulsate 0.5s infinite ease-in-out alternate;
+	-webkit-animation: loader-pulsate 0.5s infinite ease-in-out alternate;
 	animation: loader-pulsate 0.5s infinite ease-in-out alternate;
 	border-color: #aaa;
 }
 
+@-webkit-keyframes loader-pulsate {
+	from {
+		border-color: #aaa;
+		-webkit-box-shadow: 0 0 6px #ccc;
+		box-shadow: 0 0 6px #ccc;
+	}
+	to {
+		border-color: #ccc;
+		-webkit-box-shadow: 0 0 6px #f8f8f8;
+		box-shadow: 0 0 6px #f8f8f8;
+	}
+}
+
+@-moz-keyframes loader-pulsate {
+	from {
+		border-color: #aaa;
+		-moz-box-shadow: 0 0 6px #ccc;
+		box-shadow: 0 0 6px #ccc;
+	}
+	to {
+		border-color: #ccc;
+		-moz-box-shadow: 0 0 6px #f8f8f8;
+		box-shadow: 0 0 6px #f8f8f8;
+	}
+}
+
 @keyframes loader-pulsate {
 	from {
 		border-color: #aaa;
+		-moz-box-shadow: 0 0 6px #ccc;
 		box-shadow: 0 0 6px #ccc;
 	}
 	to {
 		border-color: #ccc;
+		-moz-box-shadow: 0 0 6px #f8f8f8;
 		box-shadow: 0 0 6px #f8f8f8;
 	}
 }
@@ -5001,6 +5171,8 @@ body.create-blog #buddypress .success {
 	display: none;
 	opacity: 0;
 	position: absolute;
+	-webkit-transform: translate3d(0, 0, 0);
+	-ms-transform: translate3d(0, 0, 0);
 	transform: translate3d(0, 0, 0);
 	visibility: hidden;
 }
@@ -5021,6 +5193,8 @@ body.create-blog #buddypress .success {
 	pointer-events: none;
 	text-shadow: none;
 	text-transform: none;
+	-webkit-transition: all 1.5s ease;
+	-ms-transition: all 1.5s ease;
 	transition: all 1.5s ease;
 	white-space: nowrap;
 	word-wrap: break-word;
@@ -5044,11 +5218,15 @@ body.create-blog #buddypress .success {
 	left: 50%;
 	margin-top: 7px;
 	top: 110%;
+	-webkit-transform: translate(-50%, 0);
+	-ms-transform: translate(-50%, 0);
 	transform: translate(-50%, 0);
 }
 
 .user-list .bp-tooltip:after {
 	left: 0;
+	-webkit-transform: translate(0, 0);
+	-ms-transform: translate(0, 0);
 	transform: translate(0, 0);
 }
 
@@ -5056,6 +5234,8 @@ body.create-blog #buddypress .success {
 	.user-list .bp-tooltip:after {
 		left: auto;
 		right: 0;
+		-webkit-transform: translate(0, 0);
+		-ms-transform: translate(0, 0);
 		transform: translate(0, 0);
 	}
 }
@@ -5066,6 +5246,8 @@ body.create-blog #buddypress .success {
 .notification-actions .bp-tooltip:after,
 .participants-list .bp-tooltip:after {
 	left: 0;
+	-webkit-transform: translate(0, 0);
+	-ms-transform: translate(0, 0);
 	transform: translate(0, 0);
 }
 
@@ -5074,6 +5256,8 @@ body.create-blog #buddypress .success {
 .single-message-thread-header .actions .bp-tooltip:after {
 	left: auto;
 	right: 0;
+	-webkit-transform: translate(0, 0);
+	-ms-transform: translate(0, 0);
 	transform: translate(0, 0);
 }
 
@@ -5089,11 +5273,15 @@ body.create-blog #buddypress .success {
 */
 #item-body,
 .single-screen-navs {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
 .grid > li,
 .grid > li .generic-button a {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
 	box-sizing: border-box;
 }
 
diff --git src/bp-templates/bp-nouveau/css/twentytwentyone-rtl.css src/bp-templates/bp-nouveau/css/twentytwentyone-rtl.css
index d3d05a346..e8542dc8d 100644
--- src/bp-templates/bp-nouveau/css/twentytwentyone-rtl.css
+++ src/bp-templates/bp-nouveau/css/twentytwentyone-rtl.css
@@ -906,14 +906,14 @@ body.activity-permalink #buddypress.twentytwentyone .activity-list .activity-ava
 	background: none;
 }
 
-#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:before {
+#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:before, #buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-quit:before {
 	width: 32px;
 	height: 32px;
 	color: var(--global--color-primary);
 	background: var(--global--color-background);
 }
 
-#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:hover:before {
+#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:hover:before, #buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-quit:hover:before {
 	border-radius: 50%;
 	color: var(--global--color-background);
 	background: var(--global--color-primary);
diff --git src/bp-templates/bp-nouveau/css/twentytwentyone.css src/bp-templates/bp-nouveau/css/twentytwentyone.css
index a8837db02..ccc352cad 100644
--- src/bp-templates/bp-nouveau/css/twentytwentyone.css
+++ src/bp-templates/bp-nouveau/css/twentytwentyone.css
@@ -906,14 +906,14 @@ body.activity-permalink #buddypress.twentytwentyone .activity-list .activity-ava
 	background: none;
 }
 
-#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:before {
+#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:before, #buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-quit:before {
 	width: 32px;
 	height: 32px;
 	color: var(--global--color-primary);
 	background: var(--global--color-background);
 }
 
-#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:hover:before {
+#buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-delete:hover:before, #buddypress.twentytwentyone .bp-messages-content .actions button.bp-tooltip.message-action-quit:hover:before {
 	border-radius: 50%;
 	color: var(--global--color-background);
 	background: var(--global--color-primary);
diff --git src/bp-templates/bp-nouveau/includes/messages/ajax.php src/bp-templates/bp-nouveau/includes/messages/ajax.php
index 1ab7b4259..47dfccadc 100644
--- src/bp-templates/bp-nouveau/includes/messages/ajax.php
+++ src/bp-templates/bp-nouveau/includes/messages/ajax.php
@@ -17,6 +17,7 @@ add_action( 'admin_init', function() {
 		array( 'messages_thread_read'              => array( 'function' => 'bp_nouveau_ajax_messages_thread_read', 'nopriv' => false ) ),
 		array( 'messages_get_thread_messages'      => array( 'function' => 'bp_nouveau_ajax_get_thread_messages', 'nopriv' => false ) ),
 		array( 'messages_delete'                   => array( 'function' => 'bp_nouveau_ajax_delete_thread_messages', 'nopriv' => false ) ),
+		array( 'messages_quit'                   => array( 'function' => 'bp_nouveau_ajax_quit_thread_messages', 'nopriv' => false ) ),
 		array( 'messages_unstar'                   => array( 'function' => 'bp_nouveau_ajax_star_thread_messages', 'nopriv' => false ) ),
 		array( 'messages_star'                     => array( 'function' => 'bp_nouveau_ajax_star_thread_messages', 'nopriv' => false ) ),
 		array( 'messages_unread'                   => array( 'function' => 'bp_nouveau_ajax_readunread_thread_messages', 'nopriv' => false ) ),
@@ -780,3 +781,36 @@ function bp_nouveau_ajax_dismiss_sitewide_notice() {
 		) );
 	}
 }
+
+/**
+ * @since 10.0.0
+ */
+function bp_nouveau_ajax_quit_thread_messages() {
+	$response = array(
+		'feedback' => __( 'There was a problem quiting your conversation. Please try again.', 'buddypress' ),
+		'type'     => 'error',
+	);
+
+	if ( empty( $_POST['nonce'] ) || ! wp_verify_nonce( $_POST['nonce'], 'bp_nouveau_messages' ) ) {
+		wp_send_json_error( $response );
+	}
+
+	if ( empty( $_POST['id'] ) ) {
+		wp_send_json_error( $response );
+	}
+
+	$thread_ids = wp_parse_id_list( $_POST['id'] );
+
+	foreach ( $thread_ids as $thread_id ) {
+		if ( ! messages_check_thread_access( $thread_id ) && ! bp_current_user_can( 'bp_moderate' ) ) {
+			wp_send_json_error( $response );
+		}
+
+		bp_messages_quit_thread( $thread_id );
+	}
+
+	wp_send_json_success( array(
+		'feedback' => __( 'You have left the message thread.', 'buddypress' ),
+		'type'     => 'success',
+	) );
+}
\ No newline at end of file
diff --git src/bp-templates/bp-nouveau/js/buddypress-messages.js src/bp-templates/bp-nouveau/js/buddypress-messages.js
index 73a6e0afd..db9ced0aa 100644
--- src/bp-templates/bp-nouveau/js/buddypress-messages.js
+++ src/bp-templates/bp-nouveau/js/buddypress-messages.js
@@ -978,7 +978,7 @@ window.bp = window.bp || {};
 
 				bp.Nouveau.Messages.displayFeedback( response.feedback, response.type );
 
-				if ( 'delete' === action || ( 'starred' === self.collection.options.box && 'unstar' === action ) ) {
+				if ( 'delete' === action || 'quit' === action || ( 'starred' === self.collection.options.box && 'unstar' === action ) ) {
 					// Remove from the list of messages.
 					self.collection.remove( model.get( 'id' ) );
 
@@ -1089,7 +1089,7 @@ window.bp = window.bp || {};
 
 				bp.Nouveau.Messages.displayFeedback( response.feedback, response.type );
 
-				if ( 'delete' === action || ( 'starred' === self.collection.options.box && 'unstar' === action ) ) {
+				if ( 'delete' === action || 'quit' === action || ( 'starred' === self.collection.options.box && 'unstar' === action ) ) {
 					// Remove from the list of messages.
 					self.collection.remove( thread_ids );
 
@@ -1241,7 +1241,7 @@ window.bp = window.bp || {};
 
 			bp.Nouveau.Messages.threads.doAction( action, this.model.get( 'id' ), options ).done( function( response ) {
 				// Remove all views
-				if ( 'delete' === action ) {
+				if ( 'delete' === action || 'quit' === action ) {
 					bp.Nouveau.Messages.clearViews();
 				} else if ( response.messages ) {
 					self.model.set( _.first( response.messages ) );
diff --git src/bp-templates/bp-nouveau/sass/_nouveau_messages.scss src/bp-templates/bp-nouveau/sass/_nouveau_messages.scss
index a04c262ce..e39a5dd15 100644
--- src/bp-templates/bp-nouveau/sass/_nouveau_messages.scss
+++ src/bp-templates/bp-nouveau/sass/_nouveau_messages.scss
@@ -7,7 +7,8 @@
 .message-action-star:before,
 .message-action-unstar:before,
 .message-action-view:before,
-.message-action-delete:before {
+.message-action-delete:before,
+.message-action-quit:before {
 	font-family: dashicons;
 	font-size: 18px;
 }
@@ -30,6 +31,10 @@
 	content: "\f153";
 }
 
+.message-action-quit:before {
+	content: "\f14a";
+}
+
 .message-action-delete:hover:before {
 	color: #a00;
 }
diff --git src/bp-templates/bp-nouveau/sass/twentytwentyone.scss src/bp-templates/bp-nouveau/sass/twentytwentyone.scss
index 2bc6a8de3..a4ae7a33c 100644
--- src/bp-templates/bp-nouveau/sass/twentytwentyone.scss
+++ src/bp-templates/bp-nouveau/sass/twentytwentyone.scss
@@ -1227,7 +1227,8 @@ body {
 				border: none;
 				background: none;
 
-				&.message-action-delete {
+				&.message-action-delete,
+				&.message-action-quit {
 
 					&:before {
 						width: 32px;
