How to style data-table search panel for the whole table?

Question

The search panel at the top of the table does not appear for the whole table. Just shows till the screen fits and when you scroll, it is not extended.

Here is the data-table code.

$("#standardList").dataTable({
                  "aoColumnDefs": [
                               {
                                targets: ['_all'],
                                "bLengthChange": false, 
                                "bSort": true, 
                                "bFilter": true, 
                                "aaSorting": [],
                                "bAutoWidth": true,
                                "scrollX": true,
                                "oLanguage": {
                                      "sSearch": "Search: ",
                                      "sEmptyTable": "<div class='portlet-msg-alert'>No standards Found</div>" 
                                    },
                                    "sPaginationType": "full_numbers"
                            }]
                   });

https://i.stack.imgur.com/KH3G3.png