Base: Add an elliptical outline border HTML example

Author: https://github.com/MacDue
Commit: 4e21835e70
Pull-request: https://github.com/SerenityOS/serenity/pull/14274
Reviewed-by: https://github.com/linusg

Base/res/html/misc/border-radius.html

@@ -172,6 +172,14 @@
         .rect-6 {
             border-bottom-right-radius: 50%;
         }
+
+        .rect-7 {
+            border-radius: 10px 100px / 120px;
+            width: 200px;
+            height: 100px;
+            border: 1px solid black;
+            background-color: transparent;
+        }
     </style>
 </head>
 
@@ -226,6 +234,9 @@
     <em>bottom-right 50%</em>
     <div class="rect rect-6"></div>
     <br>
+    <em>All round -- MDN example 2 -- outline</em>
+    <div class="rect rect-7"></div>
+    <br>
     <br>
 
     <p>The boxes are 50x50px</p>