diff --git a/index.html b/index.html
index a3b79b77..3ba46acc 100644
--- a/index.html
+++ b/index.html
@@ -24,9 +24,25 @@
       header h1 { font-size: 300%; margin: 0.2em; }
       p.jsnote { margin: 2em; text-align: justify; }
       p.jsnote:first-child { width: 13em; margin: auto; }
+      div.dev {
+        background: rgb(43, 49, 95);
+        color: rgb(81, 181, 255);
+        position: fixed;
+        transform: rotate(-45deg);
+        width: 22em;
+        text-align: center;
+        top: 4em;
+        left: -6em;
+        font-variant: small-caps;
+        font-weight: bolder;
+        font-family: Helvetica;
+        box-shadow: 0px 5px 7px 2px rgba(0, 0, 0, 0.3);
+      }
     </style>
   </head>
   <body>
+    <div style="" class="dev">DEV PREVIEW ONLY</div>
+
     <article>
       <header>
         <h1>A Primer on Bézier Curves</h1>
