I have scroller bar is not working properly - php

Question

I have a comment section on my page, And I add a scroller for comments. If in the comments section there are no comments then I want to hide the scroller bar. In my CSS I give overflow: auto; but still it shows scroller bar when there are no comments.
CSS:
<style>
.scrollbar
{
margin-left: 30px;
float: left;
height: 300px;
width: 100%;
margin-bottom: 25px;
overflow: auto;
}
.force-overflow
{
min-height: 450px;
}
#style-6::-webkit-scrollbar-track
{
-webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3);
background-color: #F5F5F5;
}
#style-6::-webkit-scrollbar
{
width: 10px;
background-color: #F5F5F5;
}
#style-6::-webkit-scrollbar-thumb
{
background-color: #F90;
background-image: -webkit-linear-gradient(45deg,
rgba(255, 255, 255, .2) 25%,
transparent 25%,
transparent 50%,
rgba(255, 255, 255, .2) 50%,
rgba(255, 255, 255, .2) 75%,
transparent 75%,
transparent)
}
</style>
Code:
<div class="scrollbar" id="style-6">
<div style=" height:270px;" class="force-overflow">
<?php foreach ($userComments as $comment):?>
<div class="post-details-wrapper">
<?php
$postdate =strtotime($comment['timestamp']);
$now = time();
?>
<div class="col-sm-12">
<p>
<img style="height: 45px;width: 48px;border-radius:50%;" src="<?php echo base_url();echo $comment['thumb_url']?>" />
<b style="padding-right:6px;padding-left:6px;border-radius:25px;background-color:#888888;color:white;font-family:Roboto, Arial, sans-serif;font-weight:500;>"><?php echo $comment['username'];?></b>
<?php echo date('d-m-Y',$postdate);?>
</p>
</div>
<div class="col-sm-12">
<p style="font-size:15px;"><?php echo $comment['comment']?></p>
</div>
</div>
<?php endforeach;?>
</div>
</div>
In the bellow image, you can see the scroller bar present when no comments.

Answer 1

try to set: overflow-y:auto; instead of overflow:auto;
Maybe it will help

Answer 2

make scroll bar height to min-height: 300px . It may help.
.scrollbar
{
margin-left: 30px;
float: left;
min-height: 300px;
width: 100%;
margin-bottom: 25px;
overflow: auto;
}