Is there a structured language for declaring styles in a sensible way, which can then be rendered into browser specific css files, similar to what GWT does to Javascript?
It would ideally be a language that supports variables, deals with browser quirks and differences (e.g. filter:alpha vs opacity), provides an intuitive syntax for common tasks such as centering, and has a way to express fallbacks for less capable browsers.
Sass, as in Haml and Sass has some of what you're looking for.
It has variables, math, and other goodies.
The official version is Ruby based, but there are versions for other languages like PHP and Python.
It might not do EVERTHING you mentioned, but it's worth checking out.
GWT's ability to generate code on the fly and it's powerful "deferred binding" capability could definately be applied to stylesheets and allow for build-time optimization of CSS.
Right now, the "GWT way", according to styles is to include all the styles you'll need and use apply them by making use of "dependent style names". But this definitely leads to lost of useless CSS being included where it's not needed.
I know there is at least one attempt to optimize CSS at build time. This would involve combining multiple seperate stylesheets into one, and removing all non-essential whitespace (minifying). I think this might also allow you to make use of deffrred binding to essentially "optimize out" CSS from where it's not needed (ex: browser specific styles).
StyleInjector
To answer my own question (again): Less seems like one of the most interesting projects so far. CSS extension supporting variables, mixins (complex variables), nested rules, and simple arithmetic.
you might want to try HSS.
Thanks for your comments! Sass and HSS seem very similar in scope: simple and block variables, nested blocks, single line comments. HSS has the advantage of being a superset of CSS.
StyleInjector looks more ambitious and interesting. By leveraging GWT's deferred binding capabilities and introducing CSS syntax extensions like conditionals, this approach should make it easy to define not only browser specific but also locale specific styles. Also being able to reference other GWT resources directly, and automatically minimizing styles by removing and merging selectors is pretty cool. I'll definitely follow this project closely.
Related
I was going through a really nice tutorial
https://www.sitepoint.com/variables-in-css-custom-properties/
I was trying to understand the concept of custom properties in CSS. But I am really confused as since SASS/SCSS variable also do the same thing. Then when custom properties. Or is there any significant way one should prefer CSS custom properties over preprocessors.
Thank you !!
Any help much appreciated
The very simple answer is that CSS properties came long after preprocessors. One of the reasons why people preferred preprocessors was the fact that it was like a programming language with functions and variables instead of just static CSS.
With the addition of properties to vanilla CSS, you can use it without the need of any preprocessor; it's just an addition to the language.
With regards to when you should use it, the question should be: when should you use CSS preprocessors. It's when you need a lot of flexibility and a programming-language like environment. I hope this answers the question.
The sass / scss is a code compiled for the css unlike the custom css which is a home-made variable to change the style of a page.
But both methods contribute to the cascade. In my opinion, you have to look at browser compatibility and in which project context to use it
I know Bootstrap and Foundation are CSS frameworks, but I'm not sure whether LESS and SASS are CSS frameworks or preprocessors.
What is the difference between CSS frameworks and preprocessors?
From http://lesscss.org/:
Less is a CSS pre-processor, meaning that it extends the CSS language,
adding features that allow variables, mixins, functions and many other
techniques that allow you to make CSS that is more maintainable,
themable and extendable.
From http://sass-lang.com/documentation/file.SASS_REFERENCE.html
Sass is an extension of CSS that adds power and elegance to the basic
language. It allows you to use variables, nested rules, mixins, inline
imports, and more, all with a fully CSS-compatible syntax. Sass helps
keep large stylesheets well-organized, and get small stylesheets up
and running quickly, particularly with the help of the Compass style
library.
Basically both are css pre-processors, as in they allow you to write style information that later compiles to css.
Frameworks, like bootstrap, on the other hand are more like pre-made style sheets that can be used to save development time. Rather than writing out custom sheets with similar styles over and over again, you can make use of prefabricated sheets. They usually have things like resets, basic layouts, and/or grid systems built in.
There are also some frameworks written in, and designed to be used with a pre-proccessor like Less Framework 4
If you're relatively new to this stuff, I would recommend starting with plain old css. Pre-processors can be helpful, but the learning curve is a bit steeper.
As said above, LESS and SASS allow CSS to follow the DRY(Don't Repeat Yourself) principles of coding. For example if you had a CSS file where you wanted 12 items let's say; h1, h2, h3, h4, p, a, etc all to have the same color of text(let's say a salmon color), what these preprocessors allow you to do is create a variable(let's say myColor), that you can then pass into the color attribute of each of these items.
This may not sound exciting, but where it really shines is when you want to say redesign the site or alter that color to say a 'sky blue' instead of now skimming through those 3000 lines of code to find those different items (h1, h2, ... , a, etc as listed above) you'd only need to change the myColor variable from the hex/rgb/rgba color code to the one for sky blue. Which in turn would change that value for each of those items.
So essentially you need to change 1 value that's easily found, as opposed to many, which may require a lot of sifting through code.
To note though, LESS and SASS cannot be read by a standard Internet browser, instead you must use a program that compiles your LESS/SASS code into standard CSS (these programs are easy to find and most programs such as Sublime, Brackets, Atom, etc have the functionality built in or allow a package to be downloaded that does it.)
Then when you need to edit your code, you change the LESS/SASS file and recompile again.
That's just the tip of what LESS/SASS can do, but it gives you an idea hopefully of their use. Programmers are lazy, copy and pasting isn't a good option generally, as you violate the DRY principle. So this is a happy medium explained hopefully in laymans terms.
I would have to believe I can accomplish the same results as pre-processors using jQuery(the most popular ui/ux framework).
However, depending on how many people are working on one project it may a case of teams learned in SASS or LESS scripts and may not know jQuery syntax as well. They are only focused on CSS effects, which could be a plus.
If I .addClass() to multiple DOM elements with jQuery... it may be even more efficient than having a preprocessor duplicate desired code all over a css file.
Lets say that youre using Twitter Boostrap and you have their generic boostrap.css and other boostrap associated css files, and you want your own classes to have identical attributes to some of the given boostrap classes. To my understanding, you would not want to directly modify the css bootstrap files, but you would want to extend them by creating a custom.css file.
So without touching the boostrap files. How would I replicate a boostrap class for my own class? Would the only way be to copy and paste from the boostrap.css file. Or is there a way to do
.myownclass {
-- some command to replicate class 'alert alert-error' without repeating the CSS that has already been written
}
You could use a css preprocessor. Other ways already cited by other users are fine but using a css preprocessor is the best way.
Bootstrap is built using LESS, so you can use LESS. Take a look at here: http://bootstrap.lesscss.ru/less.html.
Also SASS can be used. According to me SASS is better. You find a tutorial here: http://www.1stwebdesigner.com/css/build-website-using-twitter-bootstrap-sass-1/
What are CSS preprocessors?
A browser can only understand CSS, as the styling technique for any DOM element being rendered. CSS, as a language has its own feature set, which at times might not be enough to create a clean and reusable chunk of rules. Eg. Not being able to reuse a collection of rules in multiple selectors, unavailability of variables which may lead to ambiguous pieces of data across the stylesheet. To overcome most of these limitations, the concept of a preprocessor was born – offering an advanced way of writing CSS, which extends the basic functionalities. This advanced code is later compiled as normal CSS code using respective compilers (which depends on what preprocessor you are using), which the browser will understand.
Should you use preprocessors?
The decision of adopting preprocessors for your next project, in my opinion, should be made after much analysis and solely depending on your expertise level and most importantly the project requirement and workflow of the team as a whole. Here are some tips that might help you come to a decision:
Not for beginners: If you are a beginner and starting to explore the fantastic world of CSS, I would suggest you get your hands dirty with normal CSS before moving into a framework or preprocessor of any sorts. It’s really important to understand and be able to use the core concepts of any language that you work with, and that’s true for CSS as much as any other programming language.
Are you a team of front end developers? As a team of front end developers, adopting preprocessors will be a great move. But only if somebody on the team really knows how to handle huge CSS files and structure them accordingly. By making use of the powerful features offered by the language, it is important to first structure the whole CSS into reusable chunks and define a strategy for CSS organization. Eg. Are you going with multiple CSS files for typography, forms, layout etc. Are you going for theme-able UI, where you might need to use variables extensively, etc.
Are you willing to cross the barrier? Adopting preprocessors means you are going to be implementing more programming concepts into your CSS coding approach. There will be a lot of concepts that are native to any basic programming language, which you might want to learn and implement, by using a preprocessor. This means, you will definitely need to brush-up your programming skills and might forever change the way you see a CSS code. If you are willing to cross this barrier, and feel ready to embrace the change confidently, this is for you.
In CSS this is not possible. The only way to do it, is to chain the classes in your html tags.
<div class="alert alert-error myownclass"></div>
If you are using less you can do it like this:
.myownclass {
.alert
.alert-error;
}
This will copy the settings from one class to another. The result will be the same as if you copy the contents of the class directly.
If you are using Sass you can do it without copying the class contents. Just reference the classes as shown below. This will not copy the contents, instead it will reference your custom class at the right position in your css code.
.myownclass {
#extend .alert;
#extend .alert-error;
}
Ref: Sass #extend
You would have to use LESS to avoid copy/paste:
.myClass {
.bootstrapClass;
}
Or you could use any of the other CSS preprocessors TBS has been ported to (Sass has one, not sure on the others).
You could give the element two classes - the original Bootstrap class, and then one of your own making. Then you would target it like this:
HTML
<h1 class="original_class myownclass">Hello</h1>
CSS
.original_class.myownclass {
// css code
}
Here's a little jsfiddle illustrating the concept: http://jsfiddle.net/ApEpr/
This does not require the use of a CSS preprocessor - it's just regular old CSS.
When building a relatively large website, the CSS structure ought to be properly scoped and organized right from the begininning. If no CSS framework is used then everything can be lumped together into a massive stylesheet, but this will very quickly get out of order and can become a huge maintenance liability.
For the past few years, I've broken my stylesheets into various files including: base.css, layout.css, fonts.css, elements.css, but very easily the style definitions can jump between files and this approach needs to be more strict. I haven't used a framework since I'm not a fan of preset columns and pre-defined elements in my CSS code.
What approaches, patterns or tips can you guys suggest for keeping things organized? What kinds of naming conventions, reusability practices and patterns are useful? Is this something that a framework should be used for?
I used to love LESS, but now I'm a big fan of Stylus because I think it makes even cleaner code than LESS/SASS/CSS -- no semicolons, colons, or brackets.
Because Stylus (and LESS and SASS) allow you to define variables and templates and functions, I have the following files, which should be in this order:
reset - A Stylus version of Eric Meyer's CSS reset
variables - Variables like colors, fonts, etc.
templates - Templates like border-radius, transitions, and clearfix
Stylings for each page (homepage, app, terms of service, etc)
These are all concatenated and compiled to CSS using a simple build script.
You can see what these look like; I made a GitHub repo for this stuff.
For writing consistent and manageable stylesheets CSS LESS Framework is very beneficial.
LESS provides the following mechanisms: variables, nesting, mixins, operators and functions for writing CSS codes dynamically and can run on the client-side (Internet Explorer 6+, WebKit, Firefox) and server-side, with Node.js or Rhino.
http://lesscss.org/
Regarding Stylus — lack of semicolons, colons, and brackets makes your code less readable IMO, rather than moreso.
I need to do this more generally, but a fine current example is my two menus. I have two menu classes, horizontal-menu and vertical-menu, and two sets of rules for elements like ul, li, and a under these classes. Many of these rules have things in common, like the color value for a elements. I would like to refactor the common rules and values into a 'super-class' called menu, and the have only override values in my horizontal-menu and vertical-menu classes. Is there a tool (besides the tool asking this question) that can help me with this?
The best tool for this kind of problem is Compass, a framework for defining rules which are then compiled into css for use in production. It allows you to define variables in much the same way as an imperative language.
It also has other helpful concepts such as mixins which allow the definition of a set of css properties which would be regularly used together, such that you can include that block of properties in multiple standard CSS rules. The power being that you can then edit that mixin in one place, changing the properties and having that change propagate to any CSS rule in which the mixin has been used.
I discovered Compass, and learnt how it should be used thanks, to a screencast by Chris Coyier at CSS Tricks
The only problem in this case (and most cases in fact) is that you really have to start from scratch with Compass, or find a way of integrating its work-flow into your existing one.
You may want to give csscss a shot. I wrote it in order to have an idea of how much I'm repeating myself in my own stylesheets. I'm obviously biased, but a number of people have found it helpful too. SASS, LESS, and Compass support are baked in.
Another great tool is helium which is a javascript tool that runs in the browser and lets you know of any unused rules.