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CSS overflow

{{CSSRef}} 

The CSS overflow module properties enable you to handle scrollable overflow in visual media.

Overflow happens when the content in an element box extends past one or more of the box’s edges. Scrollable overflow is the content that appears outside the element box for which you might want to add a scrolling mechanism. CSS overflow properties let you control what happens when content overflows an element box.

Painting effects that overflow the content but do not participate in the CSS box model do not affect layout. This type of overflow is also known as {{Glossary("ink overflow")}} . Examples of ink overflows include box shadows, border images, text decoration, overhanging glyphs, and outlines. Ink overflows do not extend the scrollable overflow region.

Overflow in action

Try the following example to see the effects of various overflow property values on the content overflow and scrollbars in the adjacent fixed-size box.

The example includes options to change the values for the overflow-clip-margin and width properties, as well as to programmatically scroll the content if the overflow property creates a {{Glossary("scroll container")}} . Select overflow: clip and see the effect of different overflow-clip-margin values. Select overflow: hidden or overflow: scroll to check out the various ScrollLeft and ScrollTop slider settings.

<article>
  <fieldset>
    <legend>Select options:</legend>
    <label
      ><code>overflow</code>:
      <select id="overflowValue">
        <option>hidden</option>
        <option>clip</option>
        <option>scroll</option>
        <option>auto</option>
        <option selected>visible</option>
        <option>overlay</option>
      </select>
    </label>
    <label>
      <code>overflow-clip-margin</code>:
      <input type="number" id="ocm" value="1" min="0" max="10" size="2" />
      <code>em</code>
    </label>
    <label
      ><input type="checkbox" id="wide" /> <code>width</code>:
      <code>20em</code> or <code>40em</code></label
    >
    <fieldset>
      <legend>Scroll programmatically:</legend>
      <label
        >ScrollLeft:
        <input type="range" min="0" max="100" value="0" id="scrollL"
      /></label>
      <label
        >ScrollTop:
        <input type="range" min="0" max="100" value="0" id="scrollT"
      /></label>
    </fieldset>
  </fieldset>
  <pre class="visible">&nbsp;
    Oh, Rubber Duckie, you're the one
    You make bath time lots of fun
    Rubber Duckie, I'm awfully fond of you

    Rubber Duckie, joy of joys
    When I squeeze you, you make noise
    Rubber Duckie, you're my very best friend, it's true

    Oh, every day when I make my way to the tubby
    I find a little fella who's cute and yellow and chubby
    Rub-a-dub-dubby

    <a href="#">Rubber Duckie</a>, you're so fine
    And I'm lucky that you're mine
    Rubber Duckie, I'm awfully fond of you
      </pre>
</article>

<script>
  const pre = document.querySelector("pre");
  const val = document.getElementById("overflowValue");
  const check = document.getElementById("wide");
  const ocm = document.getElementById("ocm");
  const scrollL = document.getElementById("scrollL");
  const scrollT = document.getElementById("scrollT");

  val.addEventListener("change", () => {
    if (pre.classList.contains("wide")) {
      pre.className = `wide ${val.value}`;
    } else {
      pre.className = `${val.value}`;
    }
    scrollExample();
    clipMargin();
  });

  wide.addEventListener("change", () => {
    pre.classList.toggle("wide");
    scrollExample();
  });

  ocm.addEventListener("change", () => {
    clipMargin();
  });

  scrollL.addEventListener("change", () => {
    scrollExample();
  });
  scrollT.addEventListener("change", () => {
    scrollExample();
  });

  function scrollExample() {
    pre.scrollTo({
      top: scrollT.value,
      left: scrollL.value * 2,
      behavior: "smooth",
    });
  }

  function clipMargin() {
    pre.style.overflowClipMargin = `${ocm.value}em`;
  }
</script>

article {
  display: flex;
  gap: 1em;
}

label {
  display: block;
  white-space: nowrap;
}

pre {
  border: 2px dashed crimson;
  height: 150px;
  width: 20em;
  margin-bottom: 3em;
  overflow-clip-margin: 1em;
  text-align: center;
}

.wide {
  width: 40em;
}

::before {
  font-weight: bold;
  color: white;
  background: crimson;
  display: inline-block;
  min-width: 50%;
  padding: 3px 5px;
  box-sizing: border-box;
}

.hidden {
  overflow: hidden hidden;
}
.hidden::before {
  content: "hidden: ";
}

.clip {
  overflow: clip clip;
}
.clip::before {
  content: "clip: ";
}

.scroll {
  overflow: scroll scroll;
}
.scroll::before {
  content: "scroll: ";
}

.auto {
  overflow: auto auto;
}
.auto::before {
  content: "auto: ";
}

.overlay {
  overflow: clip clip;
  overflow: overlay overlay;
}
.overlay::before {
  content: "overlay (or clip if not supported): ";
}

.visible {
  overflow: visible visible;
}
.visible::before {
  content: "visible: ";
}

article:not(:has(pre.clip)) > fieldset > label:nth-of-type(2),
article:not(:has(pre.hidden, pre.scroll, pre.auto, pre.overlay))
  fieldset
  fieldset {
  opacity: 20%;
  pointer-events: none;
}

{{EmbedLiveSample("overflow", "", "400px")}} 

A link is included in the content box above to demonstrate the effects of keyboard focus on overflow and scroll behaviors. Try tabbing to the link or programmatically scrolling the content: the content will scroll only if the enumerated <overflow> value creates a scroll container.

Reference

Properties

[!NOTE] The CSS Overflow Module Level 4 introduces the block-ellipsis, continue, max-lines, overflow-clip-margin-block, overflow-clip-margin-block-end, overflow-clip-margin-block-start, overflow-clip-margin-bottom, overflow-clip-margin-inline, overflow-clip-margin-inline-end, overflow-clip-margin-inline-start, overflow-clip-margin-left, overflow-clip-margin-right, and overflow-clip-margin-top properties. These have not yet been implemented.

Data types

Guides

Specifications

{{Specifications}} 

See also

In this article

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