change the <td > width within grid view with different width though

[Edward]

hi there, i want to change the <td> width inside the grid view.
some <td> i want it with 310 px, for instance , the first td. the second td i want it with 290 px
I try to do it over <td width = "310px"> or external css , none of them works.

maybe i just not using the right syntax.

plz help.

my code 

<div id="example" class="k-content">

 

 

<table id="grid" style="float: left; position: relative">

    <thead>

        <tr>

            <th width ="310px"data-field="FileName">File Name

            </th>

            <th  width ="290px"data-field="ID">File Identifier

            </th>

 

        </tr>

    </thead>

    <tbody>

        @foreach (var item in Model)

        {

            <tr >

                <td  class="idRank" >

                    @item.FileName

                </td>

                <td  class="idRank2"  >

                    @item.ID

                </td>

 

            </tr>

        }

    </tbody>

it works for <th>, i want the <td> match with <th>