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 enable you to 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 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
Use the following interactive example to see the effects of various overflow property values on the content overflow and scrollbars in the adjacent fixed-size box.
The example also 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 scroll container. Select overflow: clip and see the effect of different overflow-clip-margin values. Select overflow: hidden or overflow: scroll to check out different ScrollLeft and ScrollTop slider settings.
A link is included in 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 created a scroll container.
Specifications