Highlight current post title on a page

That’s easy: You should use $wp_query->current_post to retrieve the index of your custom query.

In your case query will work something like this:

<ul class="post-list">
    <?php $query = new WP_Query( array( 'post_type' => 'campaign-post' ) );         
    while ( $query->have_posts() ) : $query->the_post();
            if($query->current_post == 0){
        ?>
            <h1 class="current"><?php the_title(); ?></h1>
        <?php
        }
        else{   
        ?>
            <h1 class="normal"><?php the_title(); ?></h1>
        <?php
        }
     endwhile; ?>
</ul>

You can customize it more that suits to your need.

How it works?
You may have noticed that there is a while loop which proceeds the results (posts retrieved from the query) one by one. If somehow we get to know that this is first post then we can use the if-else structure to extract it and customize. Fortunately $wp_query->current_post tells us about the post index.

You can do this too: More customization.

CODE EDITED:

if($query->current_post == 0){
    ?>
        <h1 class="current"><?php the_title(); ?></h1>
    <?php   
    }
    elseif ($query->current_post == 1){
?>
    <h2 class="second-post"><?php the_title(); ?></h2>
<?php
    }
    else{
    ?>
        <h3 class="rest-posts"><?php the_title(); ?></h3>
    <?php

    }