*, *::after, *::before {
  box-sizing: border-box;
}

.container{
  display: -ms-flex;
  display:flex;

  -ms-flex-wrap: wrap;
  flex-wrap: wrap;
}

.block{
  -ms-flex-grow: 1;
  flex-grow: 1;

  -ms-flex-basis: 15em;
  flex-basis: 15em;
}

@media (min-width: 30em){
  .block5{
    -ms-order: -2;
    order: -2;
  }

}