footer a {
  min-width: 24px;
  min-height: 24px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

@media (max-width: 850px) {
  footer div {
    min-width: 0;
    flex-wrap: wrap;
    justify-content: center;
  }

  footer small {
    min-width: 0;
    max-width: 100%;
  }
}