How to customise toolbar icons?

[dakom]

The docs at https://github.com/Canner/canner-slate-editor/tree/master/packages/editors/canner-slate-editor show an example of customising the toolbar - but I'm not sure how to customise the look and feel of items as well as what they do?

Currently I'd like to have a logo image which opens a new window on click, but I'm more interested in docs that break it down (i.e. do I get a div that has certain styling limitations? are there strings with default actions as well as callback possibilities? etc.)