overflow

This property is a shorthand for the following CSS properties:

• overflow-x
• overflow-y

/* Keyword values */
overflow: visible;
overflow: hidden;
overflow: clip;
overflow: scroll;
overflow: auto;
overflow: hidden visible;

/* Global values */
overflow: inherit;
overflow: initial;
overflow: revert;
overflow: revert-layer;
overflow: unset;

The overflow property is specified as one or two keywords chosen from the list of values below. If two keywords are specified, the first applies to overflow-x and the second to overflow-y. Otherwise, both overflow-x and overflow-y are set to the same value.

visible

Content is not clipped and may be rendered outside the padding box.

hidden

Content is clipped if necessary to fit the padding box. No scrollbars are provided, and no support for allowing the user to scroll (such as by dragging or using a scroll wheel) is allowed. The content can be scrolled programmatically (for example, by setting the value of a property such as scrollLeft or the scrollTo() method), so the element is still a scroll container.

clip

Similar to hidden, the content is clipped to the element's padding box. The difference between clip and hidden is that the clip keyword also forbids all scrolling, including programmatic scrolling. The box is not a scroll container, and does not start a new formatting context. If you wish to start a new formatting context, you can use display: flow-root to do so.

scroll

Content is clipped if necessary to fit the padding box. Browsers always display scrollbars whether or not any content is actually clipped, preventing scrollbars from appearing or disappearing as content changes. Printers may still print overflowing content.

auto

Depends on the user agent. If content fits inside the padding box, it looks the same as visible, but still establishes a new block formatting context. Desktop browsers provide scrollbars if content overflows.

overlay Deprecated

Behaves the same as auto, but with the scrollbars drawn on top of content instead of taking up space.

Mozilla extensions

-moz-scrollbars-none Deprecated

Use overflow: hidden instead.

-moz-scrollbars-horizontal Deprecated

Use overflow-x: scroll and overflow-y: hidden, or overflow: scroll hidden instead.

-moz-scrollbars-vertical Deprecated

Use overflow-x: hidden and overflow-y: scroll, or overflow: hidden scroll instead.

-moz-hidden-unscrollable Deprecated

Use overflow: clip instead.

As of Firefox 63, -moz-scrollbars-none, -moz-scrollbars-horizontal, and -moz-scrollbars-vertical are behind a feature preference setting. In about:config, set layout.css.overflow.moz-scrollbars.enabled to true.

Overflow options include clipping, showing scrollbars, or displaying the content flowing out of its container into the surrounding area.

Specifying a value other than visible (the default) or clip creates a new block formatting context. This is necessary for technical reasons — if a float intersected with the scrolling element it would forcibly rewrap the content after each scroll step, leading to a slow scrolling experience.

In order for overflow to have an effect, the block-level container must have either a set height (height or max-height) or white-space set to nowrap.

Setting one axis to visible (the default) while setting the other to a different value results in visible behaving as auto.

The JavaScript Element.scrollTop property may be used to scroll an HTML element even when overflow is set to hidden.

overflow = 
  [ visible | hidden | clip | scroll | auto ]{1,2}  

HTML

<div>
  <code>visible</code>
  <p class="visible">
    Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium
    doloremque laudantium.
  </p>
</div>

<div>
  <code>hidden</code>
  <p class="hidden">
    Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium
    doloremque laudantium.
  </p>
</div>

<div>
  <code>scroll</code>
  <p class="scroll">
    Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium
    doloremque laudantium.
  </p>
</div>

<div>
  <code>auto</code>
  <p class="auto">
    Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium
    doloremque laudantium.
  </p>
</div>

CSS

body {
  display: flex;
  justify-content: space-around;
}

div {
  margin: 1em;
  font-size: 1.2em;
}

p {
  width: 8em;
  height: 5em;
  border: dotted;
}

p.visible {
  overflow: visible;
}

p.hidden {
  overflow: hidden;
}

p.scroll {
  overflow: scroll;
}

p.auto {
  overflow: auto;
}

Result

A scrolling content area cannot be scrolled by a keyboard-only user, with the exception of users on Firefox (which makes the container keyboard focusable by default).

As a developer, to allow non-Firefox keyboard-only users to scroll the container you will need to give it a tabindex using tabindex="0". Unfortunately, when a screen reader encounters this tab-stop, they will have no context for what it is and their screen reader will likely announce the entirety of its contents. Giving it an appropriate WAI-ARIA role (role="region", for example) and an accessible name (via aria-label or aria-labelledby) can mitigate this.

• Keyboard-Only Scrolling Areas

• Related CSS properties: text-overflow, white-space, overflow-x, overflow-y, overflow-inline, overflow-block, clip, display
• CSS Overflow and Debug scrollable overflow