Want to keep mobile view, but make desktop view adjust to screen size until reaching mobile width

[MD883W]

Currently on Stiletto Theme, and the desktop view on product pages only sticks when my window is at full screen. Anything smaller and it switches to the mobile view, which makes product images look large and skewed on a screen size between 300-900px width (ie tablet). How can I adjust the containers or grids on the product page template to keep the desktop view until max-width: 320px ?