The REM Fallback with Sass or LESS

Since a while now word has spread to use the CSS unit rem for font-sizes and values in CSS. Here I want to explain how you can use a fallback in Sass or LESS to get rem working in all browsers.

View Gist with mixins

Why rem?

Let’s look into what rem means. We know of the em unit which is relative to the font-size of the parent element it is defined on. This means if one of the parents in the DOM-tree changes its font-size, the font-size of the child element changes too. In contrast the rem unit is relative to the root element of the page (this means the html element). Thus it is possible to define a font-size once on the root and make all other sizes depending on this size. Please switch over to Snook’s blogpost explaining what rem is to get more information about it.

If you ask yourself why you should use em instead of px, Chris Coyier wrote an article on why he switched to em instead of pixels a while ago for nearly all properties using units in CSS. Read this to understand why em and thus rem is so important.

I would encourage you to use rem (or at least em) for properties like padding, margin and sometimes even width instead of pixels. It makes your design even more responsive.

The drawback of rem is that it is not supported in all browsers that are used, even though the support looks pretty good: Internet Explorer is capable of dealing with rem since version 9. The versions before need a fallback. It is supported on the major mobile browsers except Opera Mini. Let us have a look on how we can define such a fallback using Sass or LESS.

A Sass Mixin

In order to get the pixel-based auto-calculation working as a fallback we need to define the font-size as a variable in Sass or LESS.
The following examples are in Sass with the SCSS-syntax.

$main-font-size: 16px;

We can now use this default font size on the root element:

html {
  font-size: $main-font-size;

Now we define a mixin that provides a fallback pixel-based size of the property based on the variable we defined before and in rem for capable browsers.

@mixin x-rem ($property, $value) {
  #{$property}: $value * $main-font-size;
  #{$property}: #{$value}rem;
}

What the mixin does is, that it takes the $property and calculates the value in pixels. This simple mathematic function is part of Sass. The $value argument is a decimal digit.

I like to prefix my own mixins with x- to easily distinguish them from other mixins. This is a part of the Idiomatic CSS principles by Nicolas too. I think previously I prefixed them with a namespace (mostly it was the- as a prefix, so you get the-transition) – but since there is a better convention with Idiomatic CSS I switched to it.

This mixin can be called like in the following examples:

@include x-rem(font-size, 1.4);
@include x-rem(padding-left, 2);

The output that is being produced looks like this for the first example:

font-size: 22.4px;
font-size: 1.4rem;

You can use Sass’ round() function to get an integer output for the px-based output. But every browser is capable to round 22.4px by itself to 22px since it is not possible to display 0.4px after all. (LESS has the same function.)

A Few Words On The LESS Mixin

In LESS interpolation for properties is current not possible with version 1.3.x. The maintainers aim to include it in version 1.4. For the time being we need to define a workaround for properties which is basically a JavaScript function which returns a sting that consists of two properties instead of one, while the first one is - which is basically no property an thus disregarded by the browser. The second is the property that we want to use.

Here is the first line of the mixin:

-: ~`(function () { return ';@{property}: @{px-fallback}'; }())`;

This only works if the LESS compiler uses the actual JS library. It does not work with lessphp or other compilers that are not JavaScript based.

Final Words

And that is it. The mixin provides a decent fallback for rem-based sizes of all kind. Since CSS runs stable with this version of a fallback and overwrites the pixel-based value because of CSS’ cascade we can use it without any problems. It works in old Internet Explorers.

Life is easy with rem. So look at the Gist and use the rem-fallback-mixins.

Sass and LESS mixins

Credit

I want to mention that I first saw this technique used by Divya Manian a year ago (beginning of 2012) when working on the HTML5 Please API project. I am not sure who developed this technique or where it comes from. Please let me know if you have a link.

Addition: The Susy framework has a Sass mixin which lets you easily convert units including the rem unit and a fallback as described here. (Head-tip Fabian Beiner.)

Addition 2: Steffen wrote a Sass mixin which lets you use the short notation of properties like margin or padding. Even mixing values as px and rem is working. Cheers!

An Approach on Building an Advanced Initial Boilerplate

Since some time I found myself defining a good starting point for a new project over and over again. While I use HTML5 Boilerplate in nearly all of my projects it’s not enough as an initial package. Since I’m using SASS (in its dialect SCSS) and have some other things I define over and over again I decided to set up a package that lets me start easily and includes a lot of tools that are necessary for my projects.

This is an introduction to init, the starting point for projects that require a bit more than just HTML5 Boilerplate.

Visit project on GitHub       Download

Not just HTML5 Boilerplate …

With HTML5 Boilerplate we are creating an awesome starting point for front-end developers that want to use a solid boilerplate that has defaults that are useful for everyone. Besides that we want to keep it simple and straightforward. That’s why adding a preprocessor or complex dependencies to HTML5 Boilerplate is not possible.

For the team I’m working with at /gebrüderheitz and me it’s important to have a solid basis for projects we do that we can use over and over again. Other developers have this need too and that’s why there is Twitter Bootstrap or ZURB’s Foundation (just to name two) out there.
Just while developing this project my buddy Kahlil came up with a nearly similar approach: HTML5 Boilerplate on Crack. He has different things in his package then init has. Keep an eye on that.

Simplify Development

For init I decided to use Grunt.js as a development- and deployment-tool. Grunt is a Node.js based task-oriented tool that simplifies developing and deploying JavaScript a lot. Since Grunt has a big and valuable community there are a lot of plugins that you can use with it to help developing HTML and CSS too.
Currently we are thinking about including Grunt into HTML5 Boilerplate, which is a great step in moving the project to the next stage.

As stated before I love using SASS as a preprocessor and I have some structure I like to apply to my SCSS-development files which I already outlined in my post about my personal coding guidelines. This requires to have Ruby installed on your local machine to compile SCSS into a CSS-file or to use a tool like CodeKit that does everything for you. I am actually a big fan of CodeKit but also like to have the compilation as part of my whole build process for a website.

SCSS compilation is integrated in init’s Gruntfile.
By running grunt watch you start a process which watches for changes in your SCSS-files and compiles the CSS-file automatically unsing Sindre Sorhus’ awesome Grunt-plugin grunt-sass. Besides that the watch-task recognizes changes in your JavaScript files and lints them on the fly.

If you’re not dependent on any special server-environment you can easily fire up ./server.sh on your console to start a small Ruby-server with a tab in your favorite browser.

There are a lot of other goodies in the project. Please visit GitHub and read the project’s readme-file for more information.

I’d also encourage everyone to keep an eye on Yeoman since I think it can do a lot more then my package does and will be awesome. It will be available soon.

It’s Open Source

This project is Open Source and I would love to see some people chiming in and discussing the project in its current state to make it better. I’d love to get some feedback from all of you!

Apart from that please feel free to use it for your projects. It’s all under MIT License and thus pretty much there for all your needs.

Thanks for being awesome, community <3!!

SASS vs. LESS

“Which CSS preprocessor language should I choose?” is a hot topic lately. I’ve been asked in person several times and an online debate has been popping up every few days it seems. It’s nice that the conversation has largely turned from whether or not preprocessing is a good idea to which one language is best. Let’s do this thing.

Really short answer: SASS

Slightly longer answer: SASS is better on a whole bunch of different fronts, but if you are already happy in LESS, that’s cool, at least you are doing yourself a favor by preprocessing.

Chris Coyier finds an answer to what preprocessor is the better one by pointing out what the advantages of each preprocessor are. And as it turns out SASS is winning the race because it has more power and better features. So if you are asked why you use SASS, you might want to link people to this post.

My Coding Style and Guidelines

After Harry Roberts published his HTML/CSS coding style I’ve decided to follow his call and write down how I like to code and what my guidelines for HTML and CSS coding are.
This article is only a way to describe what I like to do – but it is by far not a recommendation or something. I have not really tried to “canalize” the coding style I do before but it is about time to do so and to write it down. Please let me know if you think that there are ways to do certain things better or in a more understandable way through comments.

Harry points out some over all pretty solid ways to keep the markup readable which I use too. The major one is whitespace, I think. To be true, I love whitespace. But I’ll come to this later.

General

Tabs or Spaces?

Personally I’ve learned to use tabs instead of spaces just a few weeks ago. Lea Verou lists up some arguments, why she thinks using tabs is the way to go. But there are still some use-cases for spaces she describes.
At /gebrüderheitz I’ve discussed using spaces with Steffen before. He works a lot with PHP and uses Tabs since… – ever! I have been using spaces because I ran into some difficulties with tabs in the past where code was totally wrong indented and stuff. But at the moment everything runs pretty smooth and I am happy with how it is.

Lettercase

HTML5 and CSS let you write code how ever you want to: UPPER-CASE, lower-case, CaMeL-cAsE. So this is all the same:

<section id="a-lovely-header" class="contains-a-logo">
<SECTION ID="A-LOVELY-HEADER" class="CONTAINS-A-LOGO">
<SeCtIoN iD="a-LoVeLy-HeAdEr" ClAsS="cOnTaInS-a-LoGo">

You have to make sure you use the according class in CSS and id in JavaScript, because they are both case-sensitive.

I use lower-case exclusively. I’ve never tried to use anything different as it does not seem natural to me. Apart for that, WHO THE HELL WANTS SO READ UPPER-CASE ALL THE TIME?! IS THE CODE REALLY YELLING AT YOU? HAVE YOU EVER SEEN THIS IN A SERIOUS BOOK? Ok – to be fair, I’ve never seen a serious book with all lower case. But camel-case? C’mon…
Camel-Case in JavaScript is totally perfect though.

HTML

Harry names a view key parts of HTML styling which I use and some I really do not like.

Unquoted Attributes

I never write unquoted attributes. Harry states that this is something he does, because he can. Well… That’s true. But as he points out he has some rules where he quotes attributes for example for generated content or content that changes a lot.

His opinion on using double-quotes for all the attributes is obvious, anyway:

It is more consistent on the whole, but by introducing rules I make my own consistency; if you can get away with not using quotes, then do so.

For me the rule “Don’t confuse others” applies here: When another programmer who is not familiar with writing attributes without quotes has to edit my code in a later stage of a project or just when checking the source of a project and sees this, she might be confused with what I wrote.
Apart for that, writing attributes without quotes is error-prone.

An example: You use the Media Object as described by Nicole Sullivan for your styles and need a button, you will probably add a class btn to your link. The action that this button takes care of is the primary target of a website. Thus you add another class primary-btn to the class-attribute. If you don’t use quotes, you’ll have to add them now. It may occur that you forget them. And now what?! You are screwed. This will lead into searching your template over and over again until you find this nasty little mistake you made earlier. I don’t want this! I like code that’s pretty much straightforward.

To be fair I have to say, that I use a build script for my code before it goes into production which minifies my HTML-code and thus removes unnecessary quotes. But this does not change my development coding style.

Self-Closing Tags

Omitting self-closing tags is a thing I really love about HTML (over XHTML). You can omit the closing tag. Actually I’ve seen people not using self-closing tags on images or inputs but using them in meta-tags. I don’t know what the sense behind this might be.
I just do not use them anywhere.

Optional Closing Tags

This is a thing people may get confused about, too. Just a view days ago someone re-filed the issue of missing closing tags for HTML5 Boilerplate’s 404-error-page template because he was confused of the missing stuff I guess. That’s why I try to always use the optional closing tags – again: don’t confuse anyone. At least I try to.

I remember Paul Irish had a great usage of optional closing tags for tables where you can align rows by using whitespace, so you can see the table’s layout in HTML. Not working with generated data, though.

Here’s the example

<table>
  <tr><th>Name           <th>Country       <th>Nonsense
  <tr><td>Rick Astley    <td>England       <td>Rickrolling
  <tr><td>Chuck Norris   <td>United States <td>Roundhouse-Kick
  <tr><td>Emeli Sandé    <td>Scotland      <td>Singin – Fo realz!
</table>

Whitespace

Oh yeah, whitespace. As I already pointed out I love whitespace in my code. Everything is a bit more obvious when you divide it into small parts. It gets easier to scan the code I think. Comments help with this too.
I like to divide bigger chunks of a page with a lot of whitespace. For example if you have a content-area and a sidebar, I try to keep them separate by using whitespace.
Apart from that grouping elements like definition-list-entries helps a lot with the readability of code.

I’ve made a gist with an example-file. Check it.

CSS

Using ids in CSS is something I try to avoid but it strikes me sometimes and I just do it if there are already ids defined on some elements. Mostly these are identifiers for header- or footer-sections. But I think it’s better use classes for styling concernes and ids for JavaScript and other stuff.

Anyway… The next part will not be about vanilla CSS. I use SASS (SCSS) nowadays and recently re-factored a corporate website for one of our customers at /gebrüderheitz in SASS. I want to share the way I worked with a lot of CSS in this case and did it sometimes before.

Structure

The website has a lot of styles which had to be refactored. These were organized in one big file that has about three thousand lines of code. I do not like to have a file that has so many code and is not clear by looking at it at first.
So I have decided to split up several parts into different files.

Before the refactoring we made an online style-guide, defining the elements that appear on the side. This style-guide will be used in other projects for the same customer, too and is essential for a corporate website. We tried to define as much as possible but also let designers have a free hand at what they do.

For all SASS-files I use a folder-structure which looks like this:

+ CSS
  + elements
  + helpers
  + modules
  + page
  styles.scss

The styles.scss file has a brief description of the project, who wrote the styles (copyright…) and includes (with @include) all other files which lie in the created folders.

+ helpers

helpers contains a file with pre-defined mixins, another file with all the variables for the project, a reset (in my case this is most of the HTML5 Boilerplate CSS, which contains Normalizer.css) and some other helper-classes which I use via mixins or with SASS’ @extend-method.

+ elements

In the element folder I include files with styles for styling native HTML elements. I’ve got a file named typography which contains definitions for the general copy-text, headlines, links, quotes aso. Another file contains all stylings that are connected to lists in the content (unordered-, ordered- and definition-lists). This folder also includes the styles for forms and tables.

+ modules

I mentioned the style-guide we defined for this project. This was a great help for me when dividing the CSS into parts because I was able to see which modules were needed for the page: boxes, a paginator, an accordion menu, the navigation and some other stuff.
For each module I have an own file which contains the styles of only one modules. So when I need to change something that has to do with the paginator, I’ll head over to the according file and change the desired values. This saves me a lot of searching and scrolling through a file. Apart from that, Sublime Text’s “Find in files” (cmd + Shift + F) feature lets you search trough all files in a project which is pretty handy. Text Mate has something similar I think. And if your editor does not support it, fire up the console and grep for the things you want to find.

+ page

This last folder contains all files that add a separate styling for any page or part of the website. Typical content might be the general layout and the header and footer styling for a page. Furthermore I define styles for an area of a website in this folder – e.g. if events need more styles than defined in the modules section, or a contact-form that has some extended stylings.

And More?

We have not yet done the styling for the mobile version of this website and thus the styles are not yet included into the project’s folder structure. Styles that are specific for devices with smaller width will go into a mobile-folder.
Another thing are stylesheets for print or other media. I’ve not yet found a proper way to include these. If you have any idea for this, let me know.

Whitespace & Comments

Back to the main CSS styling guidelines for my projects.

Typically I try to avoid too much rulesets in one file but sometimes you need to do this to not split one feature into several files, which is not the sense behind this modal.
Comments are a thing that help everyone reading the defined styles to unterstand them better. Most of the class names are pretty obvious and thus don’t require any further explanation. But if you define styles that are not obvious at the first glance or you need to use browser-hacks in any form it can be helpful for other programmers to include a short comment. At least I do it this way.
I try to think about “other programmers” as the programmer I might have become in three month, when I will look at the defined styles again. If I don’t know what I did three month ago, how is anyone else supposed to understand it. This needs to be avoided.

Formatting

One thing Harry mentions is that he does not use a lot of whitespace in his rulesets. I am allergic of this style of writing. I like to have really clean styles as this:

.some-rule {
  float: left;
  color: #666;
  text-decoration: underline;
}

For vendor prefixes he indents every rule so he can use typing in columns. As I use SASS I don’t really have to care about this. But I like the way he does it. I’ve done it the same way when I used to write vanilla CSS.

Indenting is somehow essential for the CSS nesting in SASS. For rules where the nesting does not work I don’t indent though.

And A Lot More

This is not everything that applies to my HTML and CSS workflow / guidelines. I hope I can write more about stuff like this in the future and share more of my thoughts. Feedback on my thoughts would be great.

Also: If you have some time, write down what your way of coding is. Share it on Twitter with the hashtag #codestyle.