How to Mastering Z-index
Predictably, the final tip in this CSS series is all about z-index. If you want to control the stacking order of elements, you can do so with z-index. But z-index will only take affect if the element also has a position value of absolute, relative or fixed. Placing elements precisely with position is great for building up complex layouts or interesting UI patterns but it’s common to want to control stacking order without moving the element from its original place on the page.
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The CSS property, Z-index is the property that defines the display order of HTML elements using relative or absolute positioning “position: relative; or position: absolute;”. The value you give to Z-Index does not matter, but the value relatively to other elements Z-Index values will define which element comes in top of others.
Z-index is an inherently tricky thing, and maintaining z-index order in a complex layout is notoriously difficult. With different stacking orders and contexts, keeping track of them as their numbers increase can be hard — and once they start to spread across CSS files, forget about it! Because z-index can make or break a UI element’s visibility and usability, keeping your website’s UI in working order can be a delicate balance.
A reader named Arjan recently emailed me telling me about a website that The Printliminator didn't work on. They had traced it back to the fact that the site used a bunch of "overlays" with ridiculously high values for z-index. The Printlimintor injects itself on the page with absolute positioning and a z-index value of 10000, which I already consider to be ridiculously high. So should we start playing this game and come back with even more ridiculously higher z-index values? I'm going with no.
The z-index CSS property specifies the z-order of an element and its descendants. When elements overlap, z-order determines which one covers the other. An element with a larger z-index generally covers an element with a lower one.
Some interface designs may call for elements to be layered or stacked on top of each other. There are many ways that elements will naturally stack on top of each other. But we can control this stacking order using a combination of the position and z-index properties. In this final episode of AtoZ CSS season one we’ll learn about: The default stacking order of the document What a stacking context is and how they interact with each other How z-index controls layer order within stacking contexts
Managing z-index across large sites can be a pain in the butt. CSS is hard to test, so it's notoriously easy to make a change that ends up, for instance, hiding some important UI under who-knows-where. If you use a CSS preprocessor, maybe we can handle it in a special way.
The CSS specs do not mention an upper limit for z-index but there is a maximum value because of the type of variable used to store that value (a 32-bit signed integer); thus the limit in modern browsers is 2,147,483,647. Despite this, there are ad guidelines that recommend using 2,147,483,648. What happens when greater values are used, like this one I found in a page once?
Flexbox is well-known for solving common layout problems such as sticky footers and equal-height columns. Beyond those capabilities, it also provides a few other useful features that aren’t so popular. Let’s explore two of them! As you probably already know, the z-index property works only on positioned elements. By default, all elements have position: static and aren’t positioned...
Have you refrained from using CSS Gradients because either you didn’t understand them, or thought the browser support for them wasn’t good enough to consider using them in your projects?
In the previous article we learned the basics of the Less mixin guards and loops. We saw that once we’ve gained a clear understanding of their structure we can use them properly. Now, we’ll explore how this knowledge can be put to practice by examining some real world examples.