excalidraw/src/components/Stack.css

.Stack {
  --gap: 0;
  display: grid;
  gap: calc(var(--space-factor) * var(--gap));
}

.Stack_vertical {
  grid-template-columns: auto;
  grid-auto-flow: row;
  grid-auto-rows: min-content;
}

.Stack_horizontal {
  grid-template-rows: auto;
  grid-auto-flow: column;
  grid-auto-columns: min-content;
}