[audreyt]

Glad you like the social collaboration part!

Re UI, each cell supports basic WikiText, and clicking the "Format" tab next to the default "Edit" shows the Format:Text dropdown that one can change to "HTML" and then click the top-left "Save to: CellCoordinate". That allows arbitrary HTML in cell presentations.

Alignment, font, etc can also be adjusted in the same tab.

If you'd like to use HTML formatting for all cells by default, the third button on that tab "Show sheet settings" allows sheet-wide formatting customizations. Hope this helps!