Specific to your usage of a Jupyter Notebook: the ability to specify table column alignment should return in a future release. (Current releases default to right-aligned everywhere.)
From PR #4130:
Allow markdown tables to specify their alignment with the :--, :--:, --: syntax while still allowing --- to default to right alignment.
This reverts a previous change (part of #2534) that stripped the alignment information from the rendered HTML coming out of the marked renderer. To be clear this does not change the right alignment default but does bring back support for overriding this alignment per column by using the gfm table alignment syntax.
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