Why Does My Overlapping Div's Background Appear Behind Its Content?

Understanding CSS Painting Order and Overlapping Elements

In the given scenario, we observe two divs with conflicting backgrounds, one overlapping the other. However, the overlapping div slides between the background and content of the underlying div due to specific CSS painting order rules.

According to the W3C's CSS Painting Order documentation, the painting order for descendants of an element with a stacking context (which the overlapping div has due to its negative margin) is as follows:

1. Stacking contexts from negative z-indices: First, any child elements with negative z-indices form their own stacking contexts and are painted in descending order.
2. In-flow non-positioned children: Next, all in-flow non-positioned block-level children (which includes the second div in this case) are painted in tree order.
3. Backgrounds and borders of in-flow block-level children: Within each child, their backgrounds and borders are painted. The overlapping div's background is painted at this stage.
4. In-flow non-positioned inline children: After painting all block-level children, any inline elements and their content are painted in tree order.
5. Stacking contexts from positive z-indices: Finally, stacking contexts from elements with positive z-indices are painted in ascending order.

Implications for Overlapping Elements

The specific issue with the overlapping divs is that the second div's background (from step 3) is painted before its text content (from step 4). This causes the text to appear in between the first div's content and background.

Fixing the Issue

To resolve this issue, you can use one of the following approaches:

• Set a positive z-index for the overlapping div: This will ensure its stacking context is painted after the first div's background.
• Use CSS position:relative on the overlapping div: This will create a new stacking context for the div and its descendents, allowing you to control the painting order using z-index.
• Add a transparent layer over the overlapping div: This will effectively move the text content to the "above" layer, bypassing the overlapping div's background.

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