how to change a comment's html structure

hi!

i am working on my template, and comment time/date are showing up in one continuous timestamp tag:

<time datetime="2015-12-21T19:09:49+00:00"> december 21st, 2015 on 19:09 </time>

i would like to have the time of day be wrapped in a span tag, so i can style it differently than the date, with css. the comment.php file on my theme uses this to list the comments, and there’s no way to edit the timestamp here:

<ol class="comment-list">
        <?php
            wp_list_comments( array(
                'style'       => 'ol',
                'format'      => 'html5',
                'short_ping'  => true,
            ) );
        ?>
    </ol>

i tried looking at my theme’s functions.php, as well as wordpress’ include files: comment.php and comment-template.php. none of them deal with the actual tag structure of the time-stamp, so there was nothing there for me to play with.

does anyone have any idea how i can do this? obviously, i’d rather do it in my theme’s functions.php than alter the wp inc stuff..

thanks!