.top-row{
            min-height: 50vh;
            min-width:  100vw;
            padding:0px;
         }
        .top-col{
            background: #CCCCCC;            
            align-content: center;
            min-height: 50vh;
            min-width: 100vw;
        }
        .bottom-col{
            background: #CCCCCC;            
            align-content: center;
            min-height: 50vh;
            min-width: 100vw;
        }
         .bottom-row{
            min-height: 50vh;
            min-width:  100vw;
            padding:0px;
        }
    </style>
</head>
<body>
<div class="container">
    <div class="row top-row">
        <div class="col-12 top-col">
            <h2>Hello</h2>
        </div>
    </div>  
    <div class ="row bottom-row">
        <div class="col-12 bottom-col">
           <h2>World</h2>
        </div>
    </div>
</div>
</body>
</html>
I want to be able to center content vertically from just editing the css portion. I have done lots of research and tried many different this but I was not able to get a solution that works.
 
    