.content {
    width: 34%;
    float: left;
    height: 500px;
}

.sidebar {
    width: 33%;
    float: left;
    height: 500px;
}

.row:after {
  content: ""; 
  display: table;
  clear: both;
}

#arrow {
    border-right:2px solid black;
    border-bottom:2px solid black;
    width:10px;
    height:10px;
    transform: rotate(-45deg);
    margin-top:40px;
}

ul li {
  position: relative;
        padding-bottom: 10px;
}

ul {
  list-style: none;
}

ul li:before{
   content: ''; 
   position: absolute;
   border-right:2px solid black;
   border-bottom:2px solid black;
   width:10px;
   height:10px;
   top: calc(50% - 4px);
   left: -20px;
   transform: translateY(-50%) rotate(-45deg);
}