Changing the width of a Checkbox in css

Set the width of the checkbox for the call field to 25 pixels, displayed only when the left margin is clear.

Not sure why I can't figure this out, it's probably something simple, again. I made sure my stylesheets and everything match up this time.

here's the html code for the item:

<p><input type="checkbox" name="call" id="call"></p>
<p><label for="call">Please contact me for a "Get to Know You" visit.</label></p>

and here is the CSS i'm trying to use:

.checkbox {
float: left;
clear: left;
width: 25px; }

This is what the form is suppose to look like (don't mind the submit and cancel buttons, havent got there yet

Here is what mine looks like with the current CSS

Is there a specific selector for just the physical checkbox? and why is it all the way up in the corner of the form?