The amount of work you put in this project is admirable, so much stuff has been added since the last time I saw it!

As I was trying the table generator again, an idea came to mind. What do you think of using horizontal rule for the borders? This would cover the full width of the column instantly based on how long the content is. I think it will be a nice option for users who want the border length adjusted automatically.
I'm just thinking of adding it as an additional option in the border style, since there are cases in which users would prefer to adjust it manually, or want a fixed column width, in which the text would simply continue in a new line like how it does currently. It would be totally up to their preference.
Something crazy would be a mix of both, in which there must be border style rules where they can choose specifically which column borders are fixed and automatic.
There also is a difference in spacing between the tool's live preview and the forum which affects the output. It's most likely because the live preview is teletyped/monospaced while the forum is not. As you can see, there seems to be more room for text in Header 1 above, compared to the one below.