php - How can I increase the width of a column in a table? -

the input of "file name" long variable, tried changing width <th> , <td> nothing seemed work. decided put whitespace: nowrap; when did clashed other columns , writing filename went on them. how can fix this?

<table class="responstable" rules='all' style='border-collapse: collapse;'> <thead>     <tr>         <th>id</th>         <th>client id</th>         <th>file name</th>           <th>payer id</th>                <th>patient_f_name</th>         <th>patient_l_name</th>         <th>cpt_code</th>         <th>insurance_voucher</th>         <th>paitent_id</th>         <th>acc_number</th>         <th>service_dos</th>         <th>local_charge_number</th>         <th>charge_amount</th>         <th>insurance_name_insurance_company</th>         <th>paid_amount_payment</th>         <th>paid_amount_vouchers</th>        </tr> </thead>   <?php      while($row = pg_fetch_array($result))     {    ?>    <tbody>       <tr <?=$row['flag'] ? "style='background-color: #fcf8e3'" : '';?>>       <td><?php echo $row['voucher_id']; ?></td>      <td><?php echo $row['client_id']; ?></td>      <td style="white-space: nowrap"><?php echo $row['file_name']; ?></td>      <td><?php echo $row['payer_id']; ?></td>       <td><?php echo $row['patient_f_name']; ?></td>       <td><?php echo $row['patient_l_name']; ?></td>       <td><?php echo $row['cpt_code'];?></td>      <td><?php echo $row['insurance'];?></td>      <td><?php echo $row['patient_id'] ?></td>      <td><?php echo $row['acc_number'] ?></td> 

{width:700px}; 

put in css style.