Thanks for the suggestion! There are currently a few options available to you to reduce the height or the top toolbar:
If you click the Microthemer logo in the top left of the interface, you can fully hide Microthemer, leaving just the preview.
Go to View > Rulers and turn the switch off to hide rulers
Go to View > Property text labels and turn the switch off to hide the text labels
In future, we will have a ‘Dock to left’ option for the styling options, will will make more room the the site preview on wide screen laptops.
Would any combination of the above adjustments satisfy your needs? Or would you still like the option to toggle the styling options as shown in your GIF?