Custom Sidebar Image Widget in Pinboard

I’m still rather new to wordpress, but so far I have had tremendous success except for a few minor details.

One of these details is consistency in image appearance across the Pinboard theme when working with sidebars. I have installed JetPack and use the Image Widget to insert an image in the sidebar. The images in the sidebar, however, once inserted do not have the same “border” and/or drop shadow that other images have throughout the side which are in posts or on pages.

Can anyone advise how to customize the appearance of the images in the sidebars, so that I may ensure all images look the same?

Thanks kindly.