.half-split {
  display: grid;
  grid-column-gap: 20px;
  grid-template-columns: calc(50% - 10px) calc(50% - 10px);
}

.left-biased-split {
  display: grid;
  grid-column-gap: 20px;
  grid-template-columns: calc(67% - 10px) calc(33% - 10px);
}

.right-biased-split {
  display: grid;
  grid-column-gap: 20px;
  grid-template-columns: calc(33% - 10px) calc(67% - 10px);
}
.third-split {
  display: grid;
  grid-column-gap: 20px;
  grid-template-columns: calc(33% - 10px) calc(33% - 10px) calc(33% - 10px);
}