When a Gliffy macro is displayed in Viewport, it has a fixed width and does not scale with window dimensions. In order to automatically scale the image, you need to apply the following CSS.

Creating macro override for Gliffy

Create a stylesheet or edit an existing one, and add this code into the stylesheet:

.gliffy-container {
   width: auto !important;
.gliffy-image {
   height: auto;