<section class="black">
<div class="line"></div>
</section>.black {
background-color: #000;
margin-top: 100px;
color: #FFF;
height: 200px;
padding-top: 50px;
}
.line {
background-color: red;
width: 300px;
height: 25px;
margin: 0 auto;
box-shadow: 0 0 100px red;
}