Using CSS to make arrow-headed div - html

Question

I am trying to implement a arrow-headed div. Below is the part of the code that is relevant to the post/question. I have been trying to figure out how to get this done for a while now but no success.
I have a grandparent div, a parent div with a child as follows
<div className="main-segment-container">
<div className="panel panel-default segment-select-box">
<div className="panel-header segment-select-box-header">MAIN SEGMENT</div>
<div className="panel-body segment-select-box-body">
<div className=has-subsegments'>
<input type="checkbox" className="form-check-input" value={checkedSegment.category_id} onChange={this.segmentChecked} />{' '}
<label className="form-check-label">{checkedSegment.name}</label>
</div>
</div>
</div>
</div>
Here is what I am trying to achieve (notice the arrowhead):
I am able to achieve this with this css:
.main-segment-container{
width: 100%
}
.has-subsegments{
background-color: #215C64;
width: 100%;
color: #fff;
position: absolute;
height: 30px;
}
.segment-select-box {
border-radius: 3px;
width: 100%;
/* max-height: 400px; */
/* overflow: scroll; */
position: relative;
}
.segment-select-box-body{
width: 100%;
max-height: 400px;
overflow: scroll;
padding: 0px;
display: inline-block;
}
.has-subsegments::after{
content: "";
margin-top: -15px;
border-top: 15px solid transparent;
border-bottom: 15px solid transparent;
position: absolute;
border-left: 21px solid #215C64;
width: 0;
height: 0px;
right: -20px;
top: 50%;
}
Problem:
When I use the css above, the .has-subsegments element seems to be at a fixed position when I scroll. Like this:
Question
How do I implement scroll without removing the element from the normal position?
Note:
When i remove scroll from .segment-select-box-body class, everything works perfect but the children list becomes very long, therefore a scroll is needed.
adding position: relative; to .segment-select-box-body class makes the :after pseudo-element invisible.
EDIT
See JSFIDDLE here : https://jsfiddle.net/uuwhndgu/16/

Answer 1

EDIT
Thanks for posting the jsfiddle. I don't think, what you're trying to achieve is possible the way you are trying to do it.
I updated the fiddle with a suggested workaround/fix: https://jsfiddle.net/uuwhndgu/34/
what I did, is giving the wrapping col a little more width (you probably would have to either increase the col to .col-md-3 or decrease the width of .segment-select-box a little. You probably need to do the latter anyway), a max-heightof 200px and a overflow-y: scroll;. I set the width of .segment-select-box to 90% and changed position: absolute;of .has-subsegments to position: relative;. I don't know if this helps you but I BELIEVE, that there aren't many ways to achieve what you are trying to achieve.
Original answer
I am not quite sure how you intend this thing to behave. But if the highlighted entry (the one with the arrow) just ought to stay where it was, I think you can simply replace position: absolute; with position: relative; in your .has-subsegments class. Now, I wasn't able to recreate this anything close to perfectly, because it's a react app, but still, you should get the idea:
with position: absolute; on .has-subsegments
with position: relative; on .has-subsegments