Fit IMG in DIV

[CSS]

div{

   width:100%;
    height:250px;
    display:flex;
    justify-content:center;
    align-items:center;
    overflow:hidden
}

div img{
  flex-shrink:0;
    -webkit-flex-shrink: 0;
    max-width:70%;
    max-height:90%;
}

source