.layout--section-slider {
  outline: solid 1px green;
}

.layout--section-slider > .layout__region {
  padding: 1rem;
  outline: solid 1px green;
}

.layout--section-slider > .layout__region--main {
  flex-basis: 100%;
}

@media all and (max-width: 850px) {
  .layout--section-slider {
    flex-direction: column;
  }
  .layout--section-slider > .layout__region {
    flex-basis: auto;
  }
}