JSFiddle - React, Tailwind, and code Playground

HTML

<div class="modal fade" id="modalPostBox1" tabindex="-1" role="dialog" aria-labelledby="modalPostBoxLabel" aria-hidden="true" style="border:1px solid black;">
        <div class="modal-dialog" style="max-width:400px; margin: 0 auto;">
            <div class="modal-content" style="min-height: 600px; height: auto;">
                <div class="modal-body" id="this-is-body" style="height: 430px;padding:0px; overflow: auto;">

                    <div style="width:100%; " id="sticker">
                        <img class="replyOpener" style="width:100%; " id="image_E1C9BD2F-608A-8B71-CD90-D058B3B03816" src="http://www.rtacpa.com/wp-content/themes/thesis_18/custom/rotator/sample-1.jpg" alt="">
                    </div>
                    <ol class="ordered-comments" id="modalPostCommentList" style="margin: 30px 10px 10px 10px;">
                        <li>
                            <div class="comment-1 ordered-list-items" data-id="1322B587-1DB9-C87B-A6FD-90111533319B">
                                <div class="comment-1-right">
                                    <div class="comment-name"
                                         data-commentcontent="1322B587-1DB9-C87B-A6FD-90111533319B">I didn't think it
                                        was that bad
                                    </div>
                                </div>
                            </div>
                        </li>
                        <li>
                            <div class="comment-1 ordered-list-items" data-id="E6F8ED84-4FE3-2BF7-B2C9-F90726BCC601">
                                <div class="comment-1-right">
                                    <div class="comment-name"
                                         data-commentcontent="E6F8ED84-4FE3-2BF7-B2C9-F90726BCC601">So bad that you ate
                                        it all
                                    </div>
                                </div>
                            </div>
                ...

CSS

.stick {
            position:fixed;
            top:0;
        }
li
{
    padding:5px;
}

JavaScript

$(document).ready(function() {
        var s = $("#sticker");
        var pos = s.position();
        $('#this-is-body').scroll(function() {
            var windowpos = $('#this-is-body').scrollTop();
            //console.log("Distance from top:" + pos.top + "<br />Scroll position: " + windowpos);
            if (windowpos >= 154) {
                s.addClass('stick');
            } else{
                s.removeClass('stick');
            }
        });
    });