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141). This technique, which is known as the off-left
technique, is sometimes used intentionally to hide content from visual user agents
while keeping it visible for those using assistive technologies such as screen
readers.26
Fixed Positioning
Fixed positioning is a subcategory of absolute positioning. An element whose
position property is set to fixed always has the viewport (p. 141) as its containing
block. For continuous media, such as a computer screen, a fixed element won??™t
25 This capability isn??™t supported by Internet Explorer versions up to and including 6.
26 Setting display to none isn??™t recommended, since some screen readers won??™t announce such
elements.
179 CSS Layout and Formatting
move when the document is scrolled. For paged media, a fixed element will be
repeated on every page.
Internet Explorer Compatibility
Fixed positioning isn??™t supported by Internet Explorer 6 or prior versions.
Stacking Contexts
Although we tend to regard a web page as a two-dimensional entity, boxes are
positioned in three dimensions.


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