Replace:


	<?php if (!dynamic_sidebar('main-sidebar')) : ?>
	<div class="widget-wrapper">
		<div class="widget-title"><?php _e('In Archive', 'responsive'); ?></div>
		<ul>
			<?php wp_get_archives( array( 'type' => 'monthly' ) ); ?>
		</ul>
	</div><!-- end of .widget-wrapper -->
	<?php endif; //end of main-sidebar ?>


with

	<?php if ( is_active_sidebar( 'main-sidebar' ) ) : ?>
		<?php dynamic_sidebar( 'main-sidebar' ); ?>
	<?php endif; //end of main-sidebar ?>

That way, the widget background only show up when there's content or if a widget was added.