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Centering in CSS: A Complete Guide

Centering things in CSS is the poster child of CSS complaining. Why does it have to be so hard? They jeer. I think the issue isn't that it's difficult to do, but in that there so many different ways of doing it, depending on the situation, it's hard to know which to reach for.

So let's make it a decision tree and hopefully make it easier.…

Advantages to Native CSS Variables

I tend to think variables are best left to a preprocessing step, but there are some distinct things that having them directly in CSS can do:

  1. Daniel Imms:

    [they] can change at runtime, allowing the implementation of things like theming to be done more elegantly.

    i.e. change the value of a variable on a live, rendered web page and see the changes reflected everywhere that uses that variable.

  2. Peter Gasston:

    you can set the value through the setProperty() method on

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Poll Results for “How much do you value your keyboard typing skills?”

Nearly 22,000 CSS-Tricks visitors voted in this one. A majority (72%) voted that they can type well. Only very few (6%) said they had limited typing ability. The rest in the "OK" range. The voting was broken up in a 1-10 scale. See the complete results in the sidebar of the site.

Here's the full results:…

Sponsored: Hack Reactor – The Original JavaScript Coding School

Hack Reactor is a 3-month immersive coding school focused on computer science fundamentals and JavaScript. With a twofold mission, Hack Reactor works to empower people and transform education through rapid-iteration teaching. Hack Reactor grads work at companies like Google, Adobe, OpenTable, Amazon, and numerous startups with a average starting salary of $105K and a 99% graduate hiring rate.

I personally know someone who went to a coding school and changed careers and changed their life, so I'm a believer. Apply …

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Design For Community, 13 Years Later

I had heard several people say Design for Community by Derek Powazek is a great book and was published well "before it's time." As someone who works on several sites that I very much think of as community sites, I picked it up and gave it a read. Published in 2001, the book is just over 13 years old now. Ancient history for a typical tech book. It is a tech book in that it talks about specific websites and …

Sponsored: An RSS Reader for Developers

rssheap is a web-based reader for software developers. You subscribe to tags of interest (CSS, JavaScript, PHP, Ruby, etc.), and we find great articles for you to read. Articles are sorted by how many votes they have to ensure you always read high-quality content.

I think this is a clever idea. It's easier than a typical RSS reader because there is content there the second you sign up and you find things socially. It's also better than a typical news …

CSS Guidelines

High-level advice and guidelines for writing sane, manageable, scalable CSS

Feels like a nice culmination of Harry Roberts work the last several years.…

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Starting CSS Animations Mid-Way

Say you have a @keyframe animation that animates an element all the way across the screen. From off the left edge to off the right edge. You apply it to multiple elements. But you don't want all the elements to start at the same exact position.

You can change the animation-delay so that they start at different times, but they will still all start at the same place.

Fortunately, there is a way.…

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Favicons, Touch Icons, Tile Icons, etc. Which Do You Need?

The following is a guest post by Philippe Bernard. Philippe has done research on what it takes to make a favicon (and all the related graphics and markup) such that you are covered with the best quality output everywhere. Spoiler alert: it's a lot of different graphics and markup. Also full disclosure: Philippe has built a tool to help with it he showcases in the article.

Effortless Style

Some clever stuff in here regarding styling content that is just regular HTML (perhaps as produced from Markdown). No classes or attributes of any kind, no extra HTML, no JavaScript, no nothin'. Content like that is 1) easier for anyone to produce 2) going to last.…

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How To Add Page Transitions with CSS and smoothState.js

The following is a guest post by Miguel Ángel Pérez. Miguel has been working at Weblinc on ways to transition pages on websites more gracefully. On single-page applications, we have more opportunity for this since we aren't fighting the page reload. But traditional sites with page reloads, you can still be quite graceful with some help from CSS and JS. In this article Miguel focuses on setting up the CSS to do this and making it work with his

Sponsor: New Creative Market Bundle! $39 for loads of design resources

Creative Market sells loads of design resources. From high quality stock photography and vector art, to print design and web templates, to really fancy stuff like Photoshop actions for getting awesome effects easily.

Once in a while, they put together a bundle of resources you can buy and then have access to download forever from your account. They are packed with all the great stuff I mentioned. Purchased individually, everything together would be quite expensive. But for this week only,

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CSS-Tricks Chronicle XVIII

Lots of stuff happening lately and far too long since I've done a Chronicle! Where I've been, where I'm going, things I've done, things I'm doing, etc.…

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Swapping Out SVG Icons

Let's say you're using inline SVG and want to change the SVG icon that is displayed in an element on state change, like changing a class or on :hover/:focus. There are a number of ways you can approach that.…

Pure CSS parallax scrolling websites

Keith Clark explains the core concept behind parallax scrolling (e.g. different elements scroll at different rates) with just CSS. It's a devilishly clever (yet simple) combination of 3D transforms to push the element "away" from the screen, affecting it's scroll rate, while adjusting the scale so the element appears at it's original size.

Scott Kellum and Brenna O'Brien worked up a Sass @mixin for it a while back which makes it even easier.…

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Beginner Concepts: How CSS Selectors Work

Are you new to CSS? This article is for you! Perhaps the biggest key to understanding CSS is understanding selectors. Selectors are what allows you to target specific HTML elements and apply style to them. Let's not think about style right now though, let's just focus on the selecting.…

Sponsored: Improve website UX with Hotjar Insights

Hotjar Insights is a web app to help you understand your website visitors. It combines a lot of insight tools (that you might pay for separately) into one unified platform. Heatmaps that tell you where your users are clicking. Feedback forms. Exit polls. Surveys. Video recordings of users using your site. A platform for recruiting people to do user testing for you. Live chat integration. Funnel analysis. And of course, more :)

If you are a designer, UX specialist or …

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Clever Uses for Step Easing

The following is a guest post by Julian Shapiro. Julian has been working on Velocity.js recently, which he has written about here on CSS-Tricks before. Julian lives in a world of animation, so it's no surprise he's collected together some interesting examples of exotic animation techniques. Here he shares all about step easing, which you might not even be aware of. A type of animation transition that jumps from keyframe to keyframe in a set number of steps, rather

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JavaScript Event Madness! Capturing *all* events without interference

The following is a guest post by Matthias Christen and Florian Müller from Ghostlab. Ghostlab is cross-browser cross-device testing software for Mac and PC. One of the things I'm very impressed Ghostlab can do is sync the events from one browser to all the others. Scroll one page, the others you are testing scroll. Click somewhere on one page, that same click happens on the others. I asked them about how the heck it does that when there is

CSS Triggers

When you change a CSS properties value, the browser needs to react to your change. Some values change the layout of the page. For instance, a change in width requires the browser to update layout, then "paint" any pixels that have changed, then "composite" them together. That's a lot of work. Some CSS properties can be changed more inexpensively. For instance, a change in background-image doesn't require any layout changes, but does require paint and composite.

Paul Lewis did all …

RWD Bloat

Dave Rupert does an in-depth analysis of his own responsive site to figure out where he's at, identify places to improve, and evaluate the idea going around that responsive design is at fault for bloated websites.

Says Dave:

Expect RWD to add ~10%

Update: Update.…

GitHub’s CSS

Mark Otto takes us on a tour of the CSS of GitHub.com. So great to read a straight-talking bit like this, warts and all.

This is 90% the same as we do things at CodePen. One major difference is that they combine all their CSS into two files and just serve them on all pages. I suppose that way once you've visited any page of GitHub.com, you've browser-cached all the CSS you'll ever need there. I have tended to go …

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Guide to Responsive-Friendly CSS Columns

The following is a guest post by Katy Decorah (edited by Jason Morris). Katy was researching CSS columns and how they can work responsively, as there wasn't much information she could find out there on the subject. So, like a hero, she wrote it all up. Here's Katy:

With CSS columns you can create a print-inspired layout with little added markup that can adapt beyond a fixed canvas. A supported browser will make calculations to wrap and balance content …

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Sponsored: Tower 2.0 is Here – To Make Git Easy!

The following is a guest post by Tobias Günther. Together with his team, Tobias creates Tower, a Git client for Mac. I personally use it every day. Just this week, they released version 2 of Tower, which I was a beta tester for. I'll let him explain all about Tower, why they created it, and what's new in this version.

Responsive Images: Use Cases and Documented Code Snippets to Get You Started

Andreas Bovens put together this epic recipe list for <picture> / <img srcset>. There are four scenarios:

  • Do my image sizes change depending on my responsive design rules?
  • Do I want to optimize for high-dpi screens?
  • Do I want to serve images with different mime types to browsers that support them?
  • Do I want to serve different art depending on certain contextual factors?

Then Andreas shares what the code would look like for all of those plus any

Hacks for dealing with specificity

The overall point here by Harry Roberts is to keep the specificity on your selectors as low as you can. The end result of that effort is:

  1. More reusable styles.
  2. When you need to override that style, you have opportunities to nudge that specificity a bit higher while still being reusable and not fighting yourself.
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Authoring Critical Above-the-Fold CSS

The following is a guest post by Ben Edwards. I saw Ben tweet about a simple Sass @mixin that allowed you designate bits of CSS as being "critical" - the idea being to load that critical CSS first and defer the loading of the rest of the CSS until later. A clever idea, and one that is getting very popular in the web performance crowd. I thought I'd get Ben to introduce these ideas in more detail for us.

CSS Colorguard

Clever work by Alex Sexton to analyze CSS and find colors that are so close to each other they should probably be combined. You know, for efficiency and consistency. …

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Finding/Fixing Unintended Body Overflow

Ughck, accidental horizontal scrollbar, amiright?

That can be a pain, but you can usually find the offending element by surfing around the ol' DevTools and selecting elements until you find something that extends too far over to to the right (off-page to the left doesn't tend to trigger a scrollbar the same way) and adjusting it.

Sometimes I use the "Delete Node" feature of DevTools to remove stuff from the page until the scrollbar goes away. …

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A Sprinkling of PHP: Server-Side Techniques to Help with Front End Tasks

The following is a guest post by Zachary Brady. Zachary is about to take us on a beginner's journey using PHP to do some things that us front end developers sometimes need to do. To me, this kind of thing doesn't make us back end developers, but more resourceful front end developers. Zachary also focuses on PHP here, but the same concepts are available in any back end language.

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Fixed Table Layouts

There is a CSS property for tables that, it seems to me, is well-supported, little known, and super useful. It changes the way that tables are rendered such that it gives you a sturdier, more predictable layout. …

simpl.info

Simplest possible examples of HTML, CSS and JavaScript.

by Sam Dutton.…

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The `time` Element

The following is a guest post by Ty Strong. Ty noticed a curious lack of information on the <time></time> element here on CSS-Tricks and I agreed. Can't let that happen! Take it away Ty.

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Web Technologies Hanging Out Together

As a beginner, understanding how the different languages you learn interact with each other can be confusing. I thought we could pair up a variety of languages to see where they intersect and communicate. …

rebeccapurple = #663399

... it is suggested to add the named color 'rebeccapurple', for value #663399, to CSS Color Level 4. This is a tribute to Eric Meyer's daughter who recently passed away and a mark of support from all the Web community to Eric. I requested to ping Eric to be absolutely sure he is ok with this; he responded "he was honored by the gesture, and would love to accept it".

I'm glad we work in a field that isn't so …

Use Cases and Requirements for Element Queries

This is a perfect example of making a case for new language features. Not just a vague "element queries! that would be awesome!" but laying out a real-world scenario, what we have to do to achieve it now, and why that's not ideal. Of course there are big challenges (see this and this) but those debates can be held elsewhere and not muddy the "why we need it" explanation.…

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Async Attribute and Scripts At The Bottom

A reader recently wrote in and (essentially) asked me:

Is there any reason to use the async attribute when the script is already at the bottom of the page?

I'm not a master at this stuff, but this is how I understand it...…

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Cascading SVG Fill Color

One time someone told me their biggest problem with SVG icons is that they didn't match the color of text they were by. In fact it was such a big problem for them, that despite seeing the advantages of SVG icons they were sticking with icon fonts. I didn't think of it at the time, but there is a pretty easy solution for this.…

Everything You Need to Know About the CSS will-change Property

Sara Soueidan lets us know translateZ(0); is out and will-change: transform; (et al) is in. The general tips being: use sparingly, apply before you need it, be honest about what really needs it.

There is some backlash about this, mostly centered around the idea that browsers should be handling this for us. The opposition saying it's too hard for browsers to know, so this is essentially browsers and devs meeting in the middle. Sounds a lot like the responsive images …