fixed positioning
Fixed positioning is a subcategory of absolute positioning. The only difference is that for a fixed positioned box, the containing block is established by the viewport. For continuous media, fixed boxes do not move when the document is scrolled. In this respect, they are similar to fixed background images. For paged media (where the content of the document is split into one or more discrete pages), boxes with fixed positions are repeated on every page. This is useful for placing, for instance, a signature at the bottom of each page. Boxes with fixed position that are larger than the page area are clipped. Parts of the fixed position box that are not visible in the initial containing block will not print.
The box’s position is calculated according to the ‘absolute’ model, but in addition, the box is fixed with respect to some reference. In the case of handheld, projection, screen, tty, and tv media types, the box is fixed with respect to the viewport and does not move when scrolled.
fixed
‘ in a media-dependent way. For instance, an author may want a box to remain at the top of the viewport on the screen, but not at the top of each printed page. The two specifications may be separated by using an @media rule, as in:
@media screen { #logo {position: fixed;} } @media print { #logo {position: static;} }
In Gecko/20100401 Firefox/3.6.3, without a top
, right
, bottom
, or left
value a fixed positioned box may not show up.
IE6 ignores position:fixed
, but authors can use this hack.
position:fixed
is pretty broken when it comes to mobile devices, read the [sixth] position value.