Block Styles appear in both the block's toolbar and in the editor's sidebar. Currently, styles are shown with both a rendered preview and a name. The previews are a little too small to be helpful, but also add to the overall height of the sidebar accordion. Here's how it look when a plugin adds just a few styles to the Button block:

The overall height of the accordion in the screenshot above is about 570px. It ends up pushing down more important controls like Typography and Color.

Lets move the previews so they only appear when the style is hovered or has keyboard focus. This reduces the overall footprint, and also puts more emphasis on the style's name.