diff --git a/app/assets/stylesheets/alchemy/elements.scss b/app/assets/stylesheets/alchemy/elements.scss
index 1aedd7ac55..d7c4caae54 100644
--- a/app/assets/stylesheets/alchemy/elements.scss
+++ b/app/assets/stylesheets/alchemy/elements.scss
@@ -13,6 +13,11 @@
   .elements-window-visible & {
     transform: translate3d(0, 0, 0);
   }
+
+  // Fix for Tinymce fullscreen window positioning issues (GH#1511)
+  .mce-fullscreen & {
+    width: calc(100vw - #{$collapsed-main-menu-width - $default-border-width});
+  }
 }
 
 #element_area {
diff --git a/app/assets/stylesheets/tinymce/skins/alchemy/skin.min.css.scss b/app/assets/stylesheets/tinymce/skins/alchemy/skin.min.css.scss
index af89115672..ec4467346a 100755
--- a/app/assets/stylesheets/tinymce/skins/alchemy/skin.min.css.scss
+++ b/app/assets/stylesheets/tinymce/skins/alchemy/skin.min.css.scss
@@ -28,9 +28,6 @@
   direction: ltr;
 }
 
-.mce-widget button {
-}
-
 .mce-container *[unselectable] {
   user-select: none;
 }
@@ -70,6 +67,8 @@
   overflow: hidden;
   height: 100%;
   z-index: 100;
+  background: #fff;
+  border-radius: 0;
 
   .mce-resizehandle {
     display: none;
@@ -337,21 +336,6 @@ div.mce-tinymce-inline {
   }
 }
 
-.mce-fullscreen {
-  border: 0;
-  padding: 0;
-  margin: 0;
-  overflow: hidden;
-  background: #fff;
-  height: 100%;
-}
-
-div.mce-fullscreen {
-  position: fixed;
-  top: 0;
-  left: 0;
-}
-
 #mce-modal-block {
   opacity: 0;
   position: fixed;