put RightPanel as sibling of .mx_RoomView_body instead of RoomView

res/css/structures/_RoomView.scss

@@ -16,11 +16,7 @@ limitations under the License.
 
 .mx_RoomView {
     word-wrap: break-word;
-    position: relative;
-
     display: flex;
-    width: 100%;
-
     flex-direction: column;
 }
 
@@ -56,8 +52,6 @@ limitations under the License.
 }
 
 .mx_RoomView_auxPanel {
-    order: 2;
-
     min-width: 0px;
     width: 100%;
     margin: 0px auto;
@@ -71,13 +65,17 @@ limitations under the License.
 }
 
 
-.mx_RoomView_body {
-    order: 3;
+.mx_RoomView .mx_MainSplit {
     flex: 1 1 0;
-    flex-direction: column;
     display: flex;
 }
 
+.mx_RoomView_body {
+    display: flex;
+    flex-direction: column;
+    flex: 1;
+}
+
 .mx_RoomView_body .mx_RoomView_topUnreadMessagesBar {
     order: 1;
 }

res/css/views/rooms/_MemberList.scss

@@ -24,7 +24,7 @@ limitations under the License.
 }
 
 .mx_MemberList .mx_Spinner {
-    flex: 0 0 auto;
+    flex: 1 0 auto;
 }
 
 .mx_MemberList_chevron {

res/css/views/rooms/_RoomHeader.scss

@@ -15,7 +15,6 @@ limitations under the License.
 */
 
 .mx_RoomHeader {
-    order: 1;
     flex: 0 0 52px;
     border-bottom: 1px solid $primary-hairline-color;
 }