Formatting text in an accordian in bootstrap 4

So I'm struggling to format an accordian in bootstrap 4 which I'm using alongside django

The basic issue with my formatting is illustrated in the picture below. The headline in the text is spilling over to outside the column of the accordian. I feel like this should be a simple fix but I can't figure it out. Code pasted below

<div class='col-xs-12 col-md-4'>
    <h3> ATP tennis </h3>
        <hr/>   
        
    <div id="accordion">
        {% for obj in tennis %}
            <div class="card">
                <div class="card-header">
                  <h5 class="mb-0">
                    <button class="first1 btn btn-link collapsed newwrap" data-toggle="collapse"
                     data-artid="{{obj.id}}" data-target="#tnis_{{ obj.id }}" aria-expanded="false" 
                     aria-controls="tnis_{{ obj.id }}">
                      {{obj.headline}} 

    
                    </button>
                  </h5>
                </div>
                <div id="tnis_{{ obj.id }}" class="collapse" aria-labelledby="headingTwo" data-parent="#accordion">
                  <div class="card-body body_pad"><a href='{{obj.url}}' target="_blank" class='body_col'>
                    {{obj.summary}} </a><br> 
                        <div class="rght3">
                        
                        <i id="{{obj.id}}" class="likes fa fa-thumbs-up" data-artid="{{obj.id}}" style="font-size:25px;color:#6666ff;"></i>
                        </div>
                  </div>
                </div>
             </div>
        {% endfor %}
        </div>
    </div>
</div>

I feel like this should in theory be a pretty simple fix. Any help would be much appreciated. The {{obj.headline}} is the culprit that is spilling over (which sits within a button tag)