Yes there is! Bookmark just added a new image resizing feature. If you click on the image on your webpage (inside the builder) you will see a double pointed arrow in the bottom right corner of your image. Click and drag on that arrow to adjust the size of your image.

Hope that answer helps.

-Jennifer@bookmark

If you want to crop your image (remove parts of the image), you can do that in the image editor in My Drive.

Here's a link to our Help guide that will walk you through the steps to crop your image.

http://www.bookmark.com/help_center/article/guide-to-the-image-editor-in-my-drive.pdf