org-html-table-align-individual-fields

org-html-table-align-individual-fields is a variable defined in `ox-html.el'.
Its value is

t

Documentation:
Non-nil means attach style attributes for alignment to each table field.
When nil, alignment will only be specified in the column tags, but this
is ignored by some browsers (like Firefox, Safari). Opera does it right
though.

You can customize this variable.