@media screen and (max-width: 600px) {
  .container {
    width: 100%;
    padding: 0 10px;
  }

  h1 {
    font-size: 42px;
  }

  h3 {
    font-size: 22px;
  }
}

@media (min-width: 600px) {
  .border-box-button {
    flex: 0 0 calc(50% - 40px);
  }
}