Hi, is it possible to change how the number "0" is displayed in the same way that VScode is doing it like in screenshot below? That way when making notes, one could quickly identify difference between a number "0" and letter "o". If not, is this that will be addressed in future updates? Thanks. I have tried different note taking apps and Siyuan is literally the best!

Suppose I have created a Notebook, I want in that Notebook to be able to add sub-Notebooks. I understand we can create a doc and sub-docs. However, I want sub-Notebooks (which are similar to subfolders). Is this possible? I haven't come across it.