Why is My Div Hidden Despite Having a Z-Index Value?

Z-Index Values: Limitations and Implementation

Question:

In my HTML page, a div with a z-index value within the range of 0-999999 is hidden behind other elements. Why does this occur? Are there limitations to the z-index property?

Answer:

Z-Index Definition:

According to CSS standards, the z-index property allows any integer or real number value, but in practice, most browsers limit the range to signed 32-bit values, typically from -2147483648 to 2147483647 (int32).

Limitations:

There is no theoretical minimum or maximum value for z-index in the CSS specification. However, browser implementations may impose practical limitations. Int32 is a common choice because it provides a large range of values while maintaining efficient memory usage.

Browser Behavior:

Most browsers strictly adhere to the int32 range limitation. Assigning a z-index value outside this range may not have any effect, or it may cause the element to display differently from the expected behavior.

Troubleshooting:

If a div with a z-index value within the valid range is still hidden behind other elements, consider the following:

• Overlapping Elements: Ensure that the div is not positioned above other elements with higher z-index values.
• CSS Cascade: Check for any CSS rules that might be overriding the z-index property and setting it to a lower value.
• Browser Quirks: Verify if there are any browser-specific behavior issues related to z-index implementation.

Additional Notes:

• The value 0 is the default z-index for all elements.
• The stacking context determines how positioned elements are rendered relative to each other based on their z-index values.

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