A Detailed Look at the Z-Index CSS Property | Impressive Webs
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z-index is probably the CSS property that is more speedily abandoned than any other. Very often — when I previously didn’t understand z-index — I would try to apply it to an element, hoping that the element would automatically “jump” to the top in the page’s stacking order.

Most CSS properties that a web developer deals with regularly are instantaneous in their application to elements on the page. For example, when you add the background-color or font-size property to an element on your page, in most cases you will see the results immediately upon page refresh. But other CSS properties are not quite as “plug and play” as we would like. The z-index property is one example of the latter. I would venture to guess that z-index is probably the CSS property that is more speedily abandoned than any other. Very often — when I previously didn’t understand z-index — I would try to apply it to an element, hoping that the element would automatically “jump” to the top in the page’s stacking order. But that didn’t happen, so I would abandon that method and try some other way to solve the problem. Maybe you’ve had the same experience. Hopefully this article will clear up some misunderstandings regarding z-index.

According to W3schools, “The z-index property sets the stack order of an element. An element with greater stack order is always in front of another element with lower stack order.”

A Detailed Look at the Z-Index CSS Property

The z-index property sets the stack order of an element.

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Z-index CSS Property