diff --git a/src/mibew/styles/chats/default/chat.css b/src/mibew/styles/chats/default/chat.css
index 98ad29e2..d3533ba9 100644
--- a/src/mibew/styles/chats/default/chat.css
+++ b/src/mibew/styles/chats/default/chat.css
@@ -506,7 +506,6 @@ ul li {
 #invitation-messages-region {
     height: 150px;
     min-height: 150px;
-    width: 388px;
     overflow-y: auto;
     padding: 0;
     font-weight: normal;
@@ -576,11 +575,17 @@ ul li {
     #logo img {
         max-width: 100%;
     }
+    #invitation-messages-region {
+        max-width: 100%;
+    }
 }
 
-/* additional trick for desktops */
+/* additional tricks for desktops */
 @media (min-width: 501px) {
     #footer {
         width: 400px;
     }
+    #invitation-messages-region {
+        width: 388px;
+    }
 }
diff --git a/src/mibew/styles/invitations/default/invite.css b/src/mibew/styles/invitations/default/invite.css
index 5a9a4d36..0f30d581 100644
--- a/src/mibew/styles/invitations/default/invite.css
+++ b/src/mibew/styles/invitations/default/invite.css
@@ -36,7 +36,6 @@
     position: fixed !important;
     bottom: 5px !important;
     right: 5px !important;
-    width: 400px !important;
     z-index: 100 !important;
     border-radius: 10px !important;
     -webkit-border-radius: 10px !important;
@@ -97,7 +96,6 @@
     max-width: 100px !important;
 }
 #mibew-invitation-frame {
-    width: 388px !important;
     height: 150px !important;
     overflow: hidden !important;
     border: 1px solid #bbc4c4 !important;
@@ -140,3 +138,24 @@
     background: -ms-linear-gradient(#e9f6fc, #c6e5f6) !important;
     background: linear-gradient(#e9f6fc, #c6e5f6) !important;
 }
+
+/* responsive design for mobile devices */
+@media only screen and (max-width: 500px) {
+    #mibew-invitation-popup {
+        max-width: 100% !important;
+    }
+    #mibew-invitation-frame {
+        max-width: 100% !important;
+    }
+}
+
+/* additional trick for desktops */
+@media (min-width: 501px) {
+    #mibew-invitation-popup {
+        width: 400px !important;
+    }
+
+    #mibew-invitation-frame {
+        width: 388px !important;
+    }
+}