Z Index

The CSS property that controls the vertical stacking order of elements on a webpage.


Z-index is a CSS property that determines the stack order of positioned elements. Elements with a higher Z-index will appear on top of the elements with a lower Z-index on a webpage. Z-index can take on any integer value, with higher values indicating a higher position in the stack order.

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Usage and Context

Z-index is frequently used in web design and development to control the layering of elements. It's especially useful for elements such as dropdown menus, pop-ups, overlays, and other elements that need to overlay other content. It's important to note that z-index only works on elements that have a position value other than static (such as absolute, relative, or fixed).


  1. What does z-index do in CSS?

    • Z-index controls the stacking order of elements on a webpage. It determines which elements appear in front of or behind others.
  2. How does z-index work?

    • Z-index works by assigning a stack level to an HTML element. Higher values result in the element appearing above others with lower values. It only works on positioned elements.
  3. Why isn't my z-index working?

    • Z-index may not work if the element doesn't have a position value of relative, absolute or fixed. Also, parent elements can affect the stacking context of child elements.
  4. Can z-index be negative?

    • Yes, z-index can be negative. A negative z-index means the element will be placed behind other elements that have a z-index of 0 or greater.
  5. Is z-index inherited?

    • No, z-index is not inherited. Each element can have its own z-index value which only affects its position in the stacking order.


  1. Greater Design Flexibility: Z-index allows for more complex and layered design capabilities.
  2. Enhanced Usability: Smart use of z-index can improve the user experience by controlling which elements are prominent and when.
  3. Better Control Over Layout: Z-index offers precise control over the stacking order of elements, allowing developers to ensure the correct visibility of elements.

Tips and Recommendations

  1. Use Minimum Values: Avoid using unnecessarily high z-index values. It's easier to manage when you keep values low and relative to each other.
  2. Consider Parent Elements: Remember that parent elements can influence the stacking context of their children. This can affect the effectiveness of your z-index values.


Understanding and using the z-index CSS property effectively can greatly enhance a website's design and usability. While it can be a powerful tool for controlling layout and visibility of elements, it is important to use it judiciously to maintain an organized and manageable codebase. From an SEO perspective, a well-structured and user-friendly site can contribute to better user engagement and potentially improved ranking.