# Horizontal and Responsive Lists > Build static and breakpoint-driven horizontal virtual lists while preserving the visible item **Source:** [https://virtuallist.svelte.page/docs/horizontal](https://virtuallist.svelte.page/docs/horizontal) --- Set `orientation="horizontal"` for an LTR horizontal list. The same prop can change at runtime: the component clears measurements from the old axis and restores the same keyed item at its logical viewport position. ```svelte item.id} {orientation}> {#snippet renderItem(item)}

{item.title}

{/snippet} ``` ## Sizing and migration - `defaultEstimatedItemSize` is the axis-neutral estimate and takes precedence over the compatibility alias `defaultEstimatedItemHeight` when both are supplied. - Items are measured along the active axis, so dynamic widths work like dynamic heights. Axis changes discard incompatible measurements. - `itemKey` is strongly recommended when items can be inserted, removed, reordered, or retained across a breakpoint. - Existing vertical lists do not need changes; `orientation` defaults to `vertical`. ## Scrolling, loading, and keys `scroll()` alignment values `start`, `end`, `nearest`, and `center` are axis-neutral. The older `top` and `bottom` values remain vertical compatibility aliases. `scrollToOffset()` also follows the active axis. Infinite loading triggers at the logical end in either orientation. When a horizontal viewport is focused, Left/Right move by 40px, Home/End go to the logical edges, and Page Up/Page Down plus Space/Shift+Space move by one viewport page with a 40px overlap. Up/Down remain available to the page and interactive descendants keep their native key behavior. Horizontal mode is LTR-only in this release. RTL normalization is not yet supported.