Step 1: To open up the Local Settings, Click on the gear icon on the middle left of the web application.

Step 2: You will now see the local Settings on the right part of your web application as shown below.

In that settings panel, you will see various options that you can edit for a Specific page. This includes font sizes of texts and puzzles, puzzle grid size, puzzle clues positioning, borders, solution settings and colors. 

Note that whatever change you make on local settings will override the settings that you may have on your global settings. 

Feel free to explore the settings until you are satisfied with your design.