body{
    background-color:pink;
    display: flex;
    flex-direction: column;
    }

   .left {
       background-color: yellow;
   } 

   .right {
       background-color: orange;
   }


   .left, .right {
       width: 100vw;
       min-height: 50vh;
   }

@media screen and (min-width: 540px){
    body{
    background-color:tan;
    }
} 

@media screen and (min-width: 720px){
    body{
    background-color:royalblue;
    }
}

@media screen and (min-width: 960px){
    body{
    background-color:steelblue;
    flex-direction: row;
    
    }

    .left, .right {
        width: 50vw;
        min-height: 50vh;
    }

}
@media screen and (min-width: 1140px){
    body{
    background-color:thistle;
    }
}