The Value of z-index

**The Value of z-index**

The z-index property is one of the most important tools any UI developer has at their disposal, as it allows you to control the stacking order of elements on a webpage. Modals, toasts, popups, dropdowns, tooltips, and many other common elements rely on it to ensure they appear above other content. While most resources focus on the technical details or the common pitfalls of the Stacking Context (we’ll get to that in a moment…), I think they miss one of the most important and potentially chaotic aspects of z-index: the value. In most projects, once you hit a certain size, the z-index values become a mess of “magic numbers”, a chaotic battlefield of values, where every team tries to outdo the others with higher and higher numbers. How This Idea Started I saw this line on a pull request a few years ago: z-index: 10001; I thought to myself, “Wow, that’s a big number...

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