.itemContainer {
    display: flex;
}
.leftSide {
   width: 50%;
}
.rightSide {
    flex: 1 1 0%;
}
.resizer {
    cursor: ew-resize;
    width: 10px;
    font-size: 2em;
    margin: 0 10px;
    border-left: 2px solid gray;
    border-right: 2px solid gray;
   
    display: flex;
    justify-content: center;
 }
.resizer div { 
    margin: auto 0;
    color: gray;
}