fix layout

src/client/styles/scss/_create-page.scss

@@ -1,11 +1,17 @@
 .modal.create-page {
   // more than tablet size
-  @include media-breakpoint-up(sm) {
+  @include media-breakpoint-down(sm) {
     .modal-dialog {
-      width: 750px;
+      max-width: 100%;
+      margin: 10px;
     }
   }
 
+  .modal-dialog {
+    max-width: 750px;
+    box-sizing: border-box;
+  }
+
   .modal-body {
     //TODO remove legend
     legend {
@@ -27,7 +33,7 @@
         }
 
         // change layout by screen size
-        @include media-breakpoint-down(xs) {
+        @include media-breakpoint-down(sm) {
           flex-direction: column;
           .create-page-button-container {
             margin-top: 10px;