Here is an easy way to crop HTML assets on the fly in ~sedna Presenter Creator.  

  1. Add a HTML asset by clicking on the + button in the bottom left of the Assets panel.


  2. Enter the website address in the inspector panel under Source [http:// is required]

  3. Select the asset and press the SPACEBAR [this will launch the preview]

  4. With the Preview running go to the inspector and adjust your Crop Margins

  5. Once you find the right crop you can add the HTML asset to your playlist/arrangement.