How to make some blur for border?

Question

https://code.sololearn.com/W5S10j6gsW09/?ref=app

Answer 1

Not possible in normal way try making division inside another division and then set opacity for the first division like this :-

<div style = "opacity:0.5;height:100px;width:100px;background-color:yellow;">
<div style = "height:80px;width:80px;background-color:red;">
</div>
</div>

Answer 2

Try
in your header
box-shadow: 0px 0px 10px 5px black;

or you can try
box-shadow: inset 0px 0px 10px 5px blue;