Hi,
thanks for your question.
The details for this are explained in the TablePress FAQ at https://tablepress.org/faq/ where you can find a special question for this.
In your case, the quickest and shortest way would be to use this “Custom CSS”:
.tablepress td {
width:20%;
}
However, I really only recommend this code, if ALL of your TablePress tables ever will have exactly 5 columns and you want those to be equal.
Otherwise, you should extend the code to use the table ID depending selectors, i.e.
.tablepress-id-2 td,
.tablepress-id-4 td,
.tablepress-id-5 td,
.tablepress-id-6 td,
.tablepress-id-7 td,
.tablepress-id-8 td {
width: 20%;
}
Regards,
Tobias