Custom CSS not displaying correctly

Hey Guys,

I’ve got a site that I’m working on: here which is going really well, right up until you add a photo to the basket.

You select the “Add to Basket” button, a small pop up asks you to select the size you wish to order and then when selected the pop up closes and a message in a div displays “Successfully added to basket” in a green border – but now the “Add to Basket” button has moved down –

This is my code, its a shame as the plugin that I’m using doesnt have the side buttons in a seperate sidebar so I’ve had to chop the page around!

<?php
	the_post( );
	get_header( ); ?>

		<div id="primary" class="content-area">
			<div id="content" class="site-content" role="main">

				<article id="post-<?php the_ID(); ?>" <?php post_class( 'image-attachment' ); ?>>
                	<header class="entry-header">
                       		<h1 class="art-postheader">View Image ID: <?php the_title(); ?></h1>
                    	</header><!-- .entry-header -->
                        <div class="entry-attachment">
                            <div class="attachment">
                                <?php the_content(); ?>
                            </div><!-- .attachment -->
                        </div><!-- .entry-attachment -->

			<div class="entry-meta">
                            <?php
                                $published_text = __( '<p><a href="%3$s" title="Return to %4$s" class="ims-button" rel="gallery">View %5$s Album</a></p>', 'xclusive' );
                                $post_title = get_the_title( $post->post_parent );
                                if ( empty( $post_title ) || 0 == $post->post_parent )
                                    $published_text  = '<span class="attachment-meta"><time class="entry-date" datetime="%1$s">%2$s</time></span>';

                                printf( $published_text,
                                    esc_attr( get_the_date( 'c' ) ),
                                    esc_html( get_the_date() ),
                                    esc_url( get_permalink( $post->post_parent ) ),
                                    esc_attr( strip_tags( $post_title ) ),
                                    $post_title
                                ); 

			    ?>
				<p class="button-space"> </p>
<?php if(get_previous_post_link()) { ?>
				<p><span class="ims-button"><?php previous_post_link( '%link', __( 'Previous') ); ?></span></p>
<?php } ?>
<?php if(get_next_post_link()) { ?>
                            	<p><span class="ims-button"><?php next_post_link( '%link', __( 'Next') ); ?></span></p>
<?php } ?>
				<?php
				if( $ImStore->active_store )
				    printf( '<p><span class="ims-button"><a href="%1$s" title="%2$s">%3$s</a></span></p>',
                                    esc_url( $ImStore->get_permalink( "shopping-cart", true, false, $post->post_parent ) ),
                                    esc_attr__( 'View Shopping Basket', 'image-store' ),
                                    __( 'View Shopping Basket', 'image-store' )
				);
				?>
                        </div><!-- .entry-meta -->
                </article><!-- #post -->

                <?php comments_template( ); ?>

			</div><!-- #content -->
		</div><!-- #primary -->

<?php get_footer(); ?>