Css Sibling Absolute Positioning

The correct answer is: No, but at least its vertical position can be affected by siblings.

As the other answers state, the position of an absolutely positioned div is relative to its ancestors. To be precice, it is relative to the first ancestor that isn't statically positioned, when traversing up the DOM-tree.

However: an absolutely positioned element will also be affected by its siblings (the ones that come before the element). If those preceding siblings are relatively positioned, and your absolutely positioned element has its top-property not set, then it's placed vertically below those relatively positioned siblings.

<div class="relativeContainer">
  <div class="relative block">relative 1</div>
  <div class="relative block">relative 2</div>
  <div class="absoluteTopZero block">absolute top 0</div>
  <div class="absoluteTopInherited block">absolute</div> 
</div>

See this fiddle: https://jsfiddle.net/fgxeu54t/28/

There is no way using absolute position, according to w3c specification:

In the absolute positioning model, a box is explicitly offset with respect to its containing block

— relatively to parent block, not to sibling one

And no way to use relative positioning, also according to to w3c specification:

Once a box has been laid out according to the normal flow or floated, it may be shifted relative to this position.

— relatively to block's position, not to sibling block

summary:

Nobody can solve problem you described

Absolute positioning is dependent on the "current positioning context", which may include a parent element (if absolutely or relatively positioned) but will never include a sibling element.

Can you reorganize your dom so that you have a parent-child instead of siblings? If so, you could set the parent's position to relative or absolute and the child's position to absolute and the child's position would remain absolute in relation to the parent.

Depending on your needs, you can float them or position both absolute with appropriate left/top/right/bottom values.

Post your markup and explain exactly what you're trying to achieve.