Why Are My Absolutely/Fixed-Positioned Elements Displaying Off-Location?

Absolute/Fixed-Positioned Elements Off-Location

In CSS positioning, absolute and fixed can be confusing, leading to misalignments. Here, we address why such elements may not display as expected.

Case 1: Absolute Grey Box Outside Relative Parent

When an element is absolutely positioned, its position is taken relative to its closest ancestor with a non-static position. In this case, the parent .container has position: relative. However, the absolute grey box is outside of its container because its top is set to auto (the default).

As per the CSS specification, when top and bottom are auto and height is not auto, top is set to the static position. This position is determined by the element's position if it were not absolutely positioned.

In this case, the static position of the grey box is outside the container because there is no margin or padding before it. Therefore, the grey box is positioned at the top-left corner of the document body, not the container.

Case 2: Grey Box Not in Top-Left Corner after Orange Box

When the grey box is moved to the second position, it is positioned after the space left by the orange box. This is because the orange box has position: relative, which creates a new stacking context.

Elements inside a stacking context are positioned relative to the nearest positioned ancestor within that context. The grey box is positioned after the orange box because it is the next positioned element within the container's stacking context.

Conclusion

Understanding the rules governing absolute and fixed positioning is crucial for accurate element placement. By considering static positions, stacking contexts, and the relationships between positioned and non-positioned elements, developers can ensure their elements are positioned as intended.

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