What does the 'z-index' property do in CSS?

What does the 'z-index' property do in CSS?

• A. Controls the visibility of elements
• B. Sets the transparency of an element
• C. Determines the stacking order of positioned elements
• D. Changes the position of an element in a grid

Answer: (C)

The 'z-index' property in CSS is used to determine the stacking order of positioned elements on a web page. When multiple elements overlap, the 'z-index' property assigns a layer level to each element, where elements with a higher 'z-index' value will appear in front of those with a lower value. This allows developers to control which elements are visible on top when they overlap. The property only works on positioned elements, which means that the elements must have their position set to either 'absolute', 'relative', 'fixed', or 'sticky' for 'z-index' to take effect. The default value of 'z-index' is 'auto', which means elements will stack in the order they appear in the HTML. To clarify the context of other choices, the visibility of elements is typically managed through the 'display' and 'visibility' properties, while transparency is controlled using the 'opacity' property. Lastly, changing the position of an element in a grid relates more to CSS Grid layout properties rather than the stacking context managed by 'z-index'.

The 'z-index' property in CSS is used to determine the stacking order of positioned elements on a web page. When multiple elements overlap, the 'z-index' property assigns a layer level to each element, where elements with a higher 'z-index' value will appear in front of those with a lower value. This allows developers to control which elements are visible on top when they overlap.

The property only works on positioned elements, which means that the elements must have their position set to either 'absolute', 'relative', 'fixed', or 'sticky' for 'z-index' to take effect. The default value of 'z-index' is 'auto', which means elements will stack in the order they appear in the HTML.

To clarify the context of other choices, the visibility of elements is typically managed through the 'display' and 'visibility' properties, while transparency is controlled using the 'opacity' property. Lastly, changing the position of an element in a grid relates more to CSS Grid layout properties rather than the stacking context managed by 'z-index'.