If Xcas does not work correctly, clear your browser cache and reload the page, with Firefox if possible.

A typical Xcas session will consist in entering commandlines that will appear in the history. Sometimes you will also edit an already entered command and reevaluate it. The screen is divided in Examples of input:
Some features are disabled by default on mobile devices because Firefox mobile does not support them, like syntax highlighting during edition of existing levels. Note also that Chrome mobile (default browser on Android devices) is much slower than Firefox (about 5 times slower), it freezes a long time during the first evaluation. Moreover Chrome mobile does not support mathml natively, it requires Mathjax to display 2d formula, this requires net access and does not always succeed.
It is highly recommended to download Firefox and run Xcas from Firefox.
On mobile devices, the builtin keyboard delete key is incompatible with the commandline, please use the del key above.