Is it possible remove white space (padding) inside cell?
Query return cell background color like this:
Select
'<span style="background-color: #B8817D">' || col_1 || '</span>' as "1",
'<span style="background-color: #B8817D">' || col_2 || '</span>' as "2",
'<span style="background-color: #F7DC6F">' || col_3 || '</span>' as "3",
'<span style="background-color: #F7DC6F">' || col_4 || '</span>' as "4"
.....

It requires a bit of hacking, but it should work.
First add this page level inline CSS:
Next the SELECT should look as follow:
Finally the result: