We have created keyboard shortcuts for the most used tools for solving a puzzle (tools you'll also find in the side panel).
Now, let's take them one by one.
Sizing: + -
When you press + or - on your keyboard, you will increase or reduce the size of the jigsaw puzzle pieces.
When you press the space bar, you will open the side panel, (the one with the three dots in the upper right corner of the page in the puzzle player). To close side panel, you can press the space bar once again.
When you press P, you will pause the timer. To unpause press P again.
When you press F, you will go to fullscreen. To exit fullscreen press F again.
Background color: 1 2 3 4 5 6 7
The background colors are assigned key 1 to 7 with 1 being the darkest and 7 the lightest.