.box17{
margin:2em 0;
position: relative;
padding: 0.5em 1.5em;
border-top: solid 2px black;
border-bottom: solid 2px black;
}
.box17:before, .box17:after{
content: '';
position: absolute;
top: -10px;
width: 2px;
height: -webkit-calc(100% + 20px);
height: calc(100% + 20px);
background-color: black;
}
.box17:before {left: 10px;}
.box17:after {right: 10px;}
.box17 p {
margin: 0;
padding: 0;
}