diff --git a/res/css/structures/_GroupGridView.scss b/res/css/structures/_GroupGridView.scss
index 3a1ff165f1..541052175d 100644
--- a/res/css/structures/_GroupGridView.scss
+++ b/res/css/structures/_GroupGridView.scss
@@ -24,6 +24,7 @@ limitations under the License.
     grid-template-columns: repeat(3, calc(100% / 3));
     grid-template-rows: repeat(2, calc(100% / 2));
     flex: 1 1 0;
+    min-width: 0;
 }
 
 .mx_GroupGridView_rightPanel {
diff --git a/res/css/structures/_MatrixChat.scss b/res/css/structures/_MatrixChat.scss
index a843bb7fee..6d8b79ecb2 100644
--- a/res/css/structures/_MatrixChat.scss
+++ b/res/css/structures/_MatrixChat.scss
@@ -73,7 +73,8 @@ limitations under the License.
 .mx_MatrixChat > :not(.mx_LeftPanel_container):not(.mx_ResizeHandle) {
     background-color: $primary-bg-color;
 
-    flex: 1;
+    flex: 1 1 0;
+    min-width: 0;
 
     /* Experimental fix for https://github.com/vector-im/vector-web/issues/947
        and https://github.com/vector-im/vector-web/issues/946.