# Block & Inline-Block Layout Sizing
## Block (`display: block`)
If a node does not specify `Style.height`, its height is the smallest height that fits its content. If a node does not specify `Style.width`, its width fills the available inline budget after margins and padding (CSS-aligned).
For `display: block`, if a node does not specify `Style.height`, its height is the smallest height that fits its content.
In engine terms, an unspecified height and `height: Auto` are the same contract for block layout:
- resolve height from intrinsic content size
- include child/content measurement plus padding/border semantics owned by the layout model
- do not stretch to consume remaining parent height just because the parent has a known height
## Implications
- block items stack vertically based on their own measured box heights
- remaining-space distribution is not part of block auto sizing
- any future fill/stretch behavior should be expressed by a different layout mode or an explicit sizing rule
## Non-rule
The following is not valid block-layout behavior:
- treating `display: block` items with unspecified height as equal-share fill items
- dividing leftover container height across block children by default
That behavior belongs to a flex-like layout contract, not block layout.
## Notes
- This rule is about block-axis sizing only
- width may still default to the normal block-layout width behavior for the containing block
- this spec describes intended behavior even where current implementation still differs
## Inline-block (`display: inline-block`)
CSS-aligned **shrink-to-fit by default**: with `width: Auto`, an inline-block
box hugs its content (text width via `text_intrinsic_width`, or renderable
bounds). An explicit `width(...)` overrides shrink-to-fit. This contrasts
with `display: block`, which fills the available inline budget when
`width: Auto`.
Implementation: `intrinsic_block_width` in
`src/engine/ecs/system/layout/measure.rs` — returns `Some(text_width)` for
inline-block text-bearing boxes; `None` for block text-bearing boxes (which
then fills available width so wrapping works).
## Related
- [`layout-intrinsic-text-measurement.md`](./layout-intrinsic-text-measurement.md) — how the layout system locates the `TextComponent` to measure when resolving intrinsic content size (the boundary rule for descending through unstyled TC wrappers).
