php- How to strip CSS in the text

I have a text editor where user can enter raw HTML as a description. In some cases, there are some CSS styles in the text editor. I want to skip through the CSS and work only on string.

Raw HTML

    <style type="text/css">.textleft{
    margin-bottom:10px;
    float:left; 
    display: inline-block;
    width:56%;
    text-align:left;
    padding-right:20px;
    padding-left:20px;
}
  .textleft > p { display: table-cell; height: 150px; vertical-align: middle; }


.imageblock{
    display:inline-block;
    margin-bottom:10px;
    width: 44%;
}

.textright{
    margin-bottom:10px;
    float:right; 
    display: inline-block;
    width:56%;
    text-align:left;
    padding-left:20px;
    padding-right:20px;
}

.containerz{
    display:block;
}


.featimage{
    vertical-align:middle;
    display:inline-block;
    width:53%;
    max-height:245px;
}

.features{
    vertical-align:middle;
    display:inline-block;
    width:46%;
    padding-left:30px;
}

.textright > p { display: table-cell; height: 150px; vertical-align: middle; }

@media screen and (max-width: 991px)   {
    .textleft, .textright, .imageblock{
        width:100%;   
        float:none;
        padding-left: 0px;
        padding-right: 0px;
    }   
    /*.imageblock > img { width:100%;}*/
    .containerz {text-align:center;}
    .textright > p, .textleft > p { height: 100%; }
    .textright, .textleft { margin-bottom: 0px; }
    .features, .featimage { padding-left: 0px; width:100%; float:none;}
    .features { padding-top: 10px;}
    .imageblock {margin-bottom: 25px;}
}
</style>
<h1><strong>WhiteCoat Clipboard<sup>&reg;</sup> - TEAL&nbsp;- Vertical Metric Medical Edition</strong></h1>

PHP strip_tags

$description  = utf8_substr(strip_tags(html_entity_decode($product_info['description'], ENT_QUOTES, 'UTF-8')), 0, 200) . '..',

above code only works if there are no CSS rules in $product_info['description']

for the above HTML, I get this

.textleft{ margin-bottom:10px; float:left; display: inline-block; width:56%; text-align:left; padding-right:20px; padding-left:20px; } .textleft > p { display: ..