overscroll-behavior-block
=========================

The **`overscroll-behavior-block`** CSS property sets the browser's behavior when the block direction boundary of a scrolling area is reached.

See `overscroll-behavior` for a full explanation.

Syntax
------


```css
/\* Keyword values \*/
overscroll-behavior-block: auto; /\* default \*/
overscroll-behavior-block: contain;
overscroll-behavior-block: none;

/\* Global values \*/
overscroll-behavior-block: inherit;
overscroll-behavior-block: initial;
overscroll-behavior-block: revert;
overscroll-behavior-block: revert-layer;
overscroll-behavior-block: unset;
```


The `overscroll-behavior-block` property is specified as a keyword chosen from the list of values below.

### Values

`auto`

The default scroll overflow behavior occurs as normal.

`contain`

Default scroll overflow behavior (e.g., "bounce" effects) is observed inside the element where this value is set. However, no scroll chaining occurs on neighboring scrolling areas; the underlying elements will not scroll. The `contain` value disables native browser navigation, including the vertical pull-to-refresh gesture and horizontal swipe navigation.

`none`

No scroll chaining occurs to neighboring scrolling areas, and default scroll overflow behavior is prevented.

Formal definition
-----------------

|  |  |
| --- | --- |
| Initial value | `auto` |
| Applies to | non-replaced block-level elements and non-replaced inline-block elements |
| Inherited | no |
| Computed value | as specified |
| Animation type | discrete |

Formal syntax
-------------
```

overscroll-behavior-block =   
  contain  |  
  none     |  
  auto       
  
```

Examples
--------

### Preventing block overscrolling

In this demo we have two block-level boxes, one inside the other. The outer box has a large `height` set on it so the page will scroll vertically. The inner box has a small `width` (and `height`) set on it so it sits comfortably inside the viewport, but its content is given a large `height` so it will also scroll vertically.

By default, when the inner box is scrolled and a scroll boundary is reached, the whole page will begin to scroll, which is probably not what we want. To avoid this happening in the block direction, we've set `overscroll-behavior-block: contain` on the inner box.

#### HTML


```html
<main>
  <div>
    <div>
      <p>
        <code>overscroll-behavior-block</code> has been used to make it so that
        when the scroll boundaries of the yellow inner box are reached, the
        whole page does not begin to scroll.
      </p>
    </div>
  </div>
</main>
```


#### CSS


```css
main {
  height: 3000px;
  width: 500px;
  background-color: white;
  background-image: repeating-linear-gradient(
    to bottom,
    rgb(0 0 0 / 0%) 0px,
    rgb(0 0 0 / 0%) 19px,
    rgb(0 0 0 / 50%) 20px
  );
}

main > div {
  height: 300px;
  width: 400px;
  overflow: auto;
  position: relative;
  top: 50px;
  left: 50px;
  overscroll-behavior-block: contain;
}

div > div {
  height: 1500px;
  width: 100%;
  background-color: yellow;
  background-image: repeating-linear-gradient(
    to bottom,
    rgb(0 0 0 / 0%) 0px,
    rgb(0 0 0 / 0%) 19px,
    rgb(0 0 0 / 50%) 20px
  );
}

p {
  padding: 10px;
  background-color: rgb(255 0 0 / 50%);
  margin: 0;
  width: 340px;
  position: relative;
  top: 10px;
  left: 10px;
}
```


#### Result

Specifications
--------------

| Specification |
| --- |
| CSS Overscroll Behavior Module Level 1 # overscroll-behavior-longhands-logical |

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* Take control of your scroll: customizing pull-to-refresh and overflow effects