WebSim is developed and tested in Mozilla browsers (Firefox and Camino),
but should (?) work the same in Internet Explorer and Safari.
For best results, make sure you are running
Firefox version 126.96.36.199
Because WebSim tends to open a lot of windows if you have multiple tableaux open, it's best to use a browser that supports tabbed browsing. In Firefox, go to the menu Tools > Options. In some versions, select Advanced, click on Tabbed Browsing, and select Force links that open new windows to open in: a new tab. In other versions, select Tabs and choose New pages should be opened in: a new tab.
So that you don't need to fret about losing internet connectivity while WebSimming, feel free to download WebSim to run locally on your own machine.