add class next and previous link in wordpress

<div class="row next-pre">

		<div class="col-md-6 col-sm-6 col-xs-6">
			<div class="previous-post">

				<?php $prev_post = get_adjacent_post( false, '', true); ?>

				<?php if ( is_a( $prev_post, 'WP_Post' ) ) { ?>
					<a href="<?php echo get_permalink( $prev_post->ID ); ?>" class="btn btn-border"><i class="fa fa-long-arrow-left"></i> Previous</a>
				<?php } ?>

			</div>
		</div>

		<div class="col-md-6 col-sm-6 col-xs-6">
			<div class="next-post">

				<?php $next_post = get_adjacent_post( false, '', false ); ?>
				<?php if ( is_a( $next_post, 'WP_Post' ) ) {  ?>
					<a href="<?php echo get_permalink( $next_post->ID ); ?>"  class="btn btn-border">Next <i class="fa fa-long-arrow-right"></i></a>
				<?php } ?>

			</div>
		</div>

	</div>