html - Make an empty span tag appear full width using no padding/margin/  -

i'm pretty sure messing me, asked me this.

put span tag inside table, nothing inside span tag. , somehow make span tag 16px wide.

no padding, margin or &nbsp. dont think possible. possible? heres html/css.

    .test{         height: 31px;         width: 16px;         background-color: red;      }           <td>16px wide</td>         <td><span class="test"></span></td>         <td>16px wide</td> 

simply set:

.test{     display: inline-block;     width: 16px; }