Change Table Column Widths in Checkout Page

Hi,

If you look at my split screen checkout page:

You can see that the address part is pretty squashed whereas the information text is given lots of space.

Question: How do I change the width of the address columns so that they're wider?

https://www.limelites.co.uk/

This is the PHP code that's calling the address, what would my stylesheet class be to tweak the width?

<div id="checkoutShipto" class="floatingBox back">
							<?php if ($displayAddressEdit) { ?>
							<div class="buttonRow forward"><?php echo '<a href="' . $editShippingButtonLink . '">' . zen_image_button(BUTTON_IMAGE_CHANGE_ADDRESS, BUTTON_CHANGE_ADDRESS_ALT) . '</a>'; ?></div>
							<?php } ?>
							<address class=""><?php echo zen_address_label($_SESSION['customer_id'], $_SESSION['sendto'], true, ' ', '<br />'); ?></address>
							</div>
							<div class="floatingBox important forward"><?php echo TEXT_CHOOSE_SHIPPING_DESTINATION; ?></div>
							</fieldset>