Style code has been inserted in order to accomplish resizing images based on the end-user's screen.  Here's how to make your image responsive:

  1. While inserting an image, click on the 'Appearance' tab.

  2. In the 'Class' dropdown menu, select '(value)'.

  3. After selecting '(value)', the field will become editable, in which you should type "img-responsive" (no quotation marks).

  4. Click 'Update'.

While every process isn't perfect, these steps should help in accomplishing making your image responsive at a 90% width of the body content area.