Primary color
Hold Ctrl to erase
Secondary color Shift
The canvas and all options are automatically saved in local storage.
You can manually save a drawing using Ctrl+S (or by selecting "Save Page As" in the context menu), then choosing "Web Page, complete" and saving the files.
Make sure to keep the stylesheet with the HTML file. The HTML can be opened in any browser to view or edit, then saved again using the above method.
You can export the drawing by taking a screenshot.