custom text field width

Hi
Can you tell me where I change the width of the text  box field in the Additional Info text areas.

I have looked all over but can not get them any wider than the 150 odd pixels which its set to as standard.
thanks
Rob

In the CSS: components/com_ajaxregister/assets/css/validate.css

Thanks I tried every bit in there and nothing changed the width of the bottom half of my form
see
www.e-techsolutions.co.uk/index.php/register-your-company

can you point me to where in this file I need to ammed
Thanks
Rob

For example you can add:
.registration form input.required,
.registration form select.required,
.registration form .checkboxes.required,
.registration form input.validate-date,
.registration form input.validate-url,
.registration form fieldset.radio,
.registration form textarea.required  {
    float: left !important;
    width: 350px;
}