# Viewport Boundary Detection

The Popup enables you to set its boundary detection functionality by using the [`collision`](https://www.telerik.com/kendo-vue-ui-develop/components/popup/api/popupprops#collision) property.

The property specifies the behavior of the component when it does not fit in the view port. By default, the Popup fits horizontally and flips vertically.

[Demo Source](https://demos.telerik.com/kendo-vue-ui/popup/viewport/source.txt)

## Suggested Links

* [API Reference of the Popup](https://www.telerik.com/kendo-vue-ui-develop/components/popup/api/popupprops)