Disable next/previous post link style

Hi,

I have a problem in one of my client site.
I create a custom loop content and also add styling to next and previous link.

This is what my script looks like :

<div class="navigation">
	<div class="pagination_custom_2"><?php next_posts_link('Previous Deals') ?></div>
	<div class="pagination_custom_1"><?php previous_posts_link('Newer Deals') ?></div>
        </div>

The problem is,
I do some styling to my previous/next link, so it look like square button, and add float left for ‘Previous Deals’ and float right to ‘Newer Deals’ so If theres is on page 1, the next square button style still shows up, without the text in it. On the last page, the previous square button style still showing up too, without the text in it.