.flex{  display: flex; 
     flex-direction: row ;
      flex-wrap: wrap;
      justify-content: flex-start;
        align-items: stretch ;
        align-content: stretch;
}


@media (max-width: 800px)  {
  .flex-child {
     width : 90vw;

  }
}


@media (max-width: 1199px) and (min-width: 801px) {
  .flex-child {
     width : 45vw;

  }
}

@media (min-width: 1200px) {
  .flex-child {
     width : 30vw;

  }
}