datatable width 100% not working

Hello,

I am trying to set 100% as width for a default data-table without rows. I set the following settings:

<

table style="width:100% !important;">
....

            var table = $("#alarmTable").DataTable({
                searching: false,
                paging: false,
                info: false,
                "autoWidth": false,
                "columns": [
                    { "width": "20%" },
                    { "width": "80%" },
                    ]
            });

and the table is drawing:

Any idea, how to set data-table 100% width?