I've recently begun working on a very large, high traffic website. We would very much like to reduce the size and number of our style sheets, minification is one route we will pursue but is anyone aware of any tools for checking ID and class use? Literally scanning the website to see what's active and what isn't?
Alternatively any software for redacting the css to reduce repition and size?
Thanks in advance
Literally scanning the website to see
what's active and what isn't?
Dust-Me Selectors is a Firefox plugin that you can use to show what css rules aren't being used.
http://www.sitepoint.com/dustmeselectors/
I can certainly recommend Page Speed (http://code.google.com/speed/page-speed/) by Google to check the performance (and possible improvements) of your webpages.
Page Speed also checks CSS and usage of classes on your webpages.
It is used in combination with Firebug.
Gzip compression in the webserver.
Expiry dates that lie far in the future to avoid redownloading the CSS files.
Alternatively any software for
redacting the css to reduce repition
and size?
Yet another level of indirection ... You (and your team) should write long CSS files with as many comments as needed and then write a tool that will publish merged files as needed (different templates need different files), stripped comments and minified as http://www.cleancss.com could do (CSSTidy). Readability comes first if you wan't to be able to modify a file in 1 month or keep track of modifications (or worse if sb else must do that!).
Other options are to reduce the number of templates used throughout the site. No need of two templates with 2px differences (grid layouts are a good way to stick to this) or inconsistent ways of displaying error messages. Define a common look and feel to your site and give instructions to webdesigners, if it isn't already done.
Related
Once upon a time I was thought by more advanced web developers (gee, when was it again? ;)) that we should avoid managing multiple CSS files and stick to one per project. It helped to improve page load speed and avoid silly mistakes when dealing with a lot overlapping CSS rules.
My question is - is this approach still valid?
Argument about page load performance doesn't seem to hold that much nowadays with awesome broadband Internet and clever web browsers with even more awesome caching capabilities.
CSS cascading can indeed be error prone, but just for inexperienced developer and having one CSS style sheet doesn't really make us bullet-proof.
I think that I would prefer to have a set of default style sheets neatly separated by components, then wire them up into one single rule by CSS #import. This would also allow me to include reset style sheet by default.
Anyone is with me?
It's not about bandwidth speed but number of http requests, this makes a lot of sense for a mobile connection.
However the approach of having different css files to keep the project modular is solid, as it helps you keeping your css organized the way you want it without having all the code in one file only. Then you can benefit of css preprocessors / minifiers to concatenate and compress all your css files in a single one for production.
this article http://www.igvita.com/2012/06/14/debunking-responsive-css-performance-myths/
has a paragraph about mobile that explains well why this is a good practice:
you are much better off downloading all of the CSS content in one shot over the initial, warmed up connection. By doing so, you will also help the user extend their battery life. If there is one optimization to be made here then it is simply: concatenate and compress.
Yes, that approach is still valid. There are dozens of articles about load optimization out there, but the general idea is as follows
Less files = less http requests made to server = better load performance
Main thing that changed over time is that now there are many tools that support merging multiple files into single at runtime. So you have separate stylesheets for better organization, debugging at development time, and those tools merge, minify and set correct caching headers at production.
I agree with you, I find no reason to keep only a single css sheet anymore, nowadays, I do exactly what you just stated, separation by component, along with lazy loading :) (php if statements etc).
I separate stuff with comments. For example divs goes to /* Divs start*/ div#somediv /* Divs end*/ /* Animations start*/ /* Animations end*/. For me this is easier than merging different css files once i've completed the project
Many people say to keep the number of external CSS and JavaScript files to minimum to reduce round trip time. For example, Google recommends maximum two CSS and JavaScript files per web site, respectively.
The problem is, I've broken up CSS code into several files depending on its nature as part of "modularization". For example, I've put CSS code that is only used in a certain part of the application in a separate file. As a result, some files have less than a hundred lines of code.
I'm a Java develper, and this is actually a recommended practice in Java, but CSS is a totally different creature and I don't know much about CSS. Here are my questions.
Does it make sense to keep as many CSS files as you see fit for readability and maintainability?
How many CSS files are manageable in a web project?
What's the average number of CSS files in web applications that you've worked on in the past?
The best solution is to write a script that combines (and minifies) multiple CSS or JS files.
You might benefit from a solution like Bundler, or Chirpy
http://www.codethinked.com/bundler-now-supports-css-and-less
http://chirpy.codeplex.com/
We use chirpy because we found a bug in Bundler that can inject query string params into you css files.
As a bonus to file consolidation, you also get .less syntax handling.
I agree with what other have said here, yes when you develop you have muliple CSS files, but for production you should merge an minify them.
However I do not agree you should merge them all into 1 single file. As the will mean people who just want to visit your home page must wait for CSS on pages x,y,z also to download.
What I usually do is have 2 or 3 CSS files.
1 small CSS file just for the home page only so it load super quick so casual visitors do not have to wait to see what my site is about
Another CSS file for every other page availble to guest users
Another CSS file for a members only sectons of the website that require a login.
You can also use scripts like HEAD.JS which will manage your CSS and javascript asynchronously
From there site http://headjs.com/
There is a common misbelief that a single combined script performs best. Wrong:
latest browsers and Head JS can load scripts in parallel. loading 3 parts in parallel instead of as a single chunk is usually faster.
if an individual file is changed the whole combination changes and you loose the benefits of caching. it's better to combine only the stable files that doesn't change often.
many popular libraries are hosted on CDN. you should take the advantage of it instead of hosting yourself
iPhone 3.x cannot cache files larger than 15kb and in iPhone 4 the limit is 25kb. And this is the size before gzipping. if you care about iPhones you should respect these limits.
As you point out, having multiple CSS files often leads to better maintainability and modularity.
The number of CSS files needed depends on the size of your project and the level of modularity in the project.
Serving up on CSS file instead of many often makes a noticeable difference in the page loading time, so the ideal solution is to have some kind of tool that combines, and maybe even compresses, the CSS files. This can easily be done in runtime by a tool such as Minify.
Combining resources can be beneficial in that it can reduce the number of HTTP requests; Reducing the number of HTTP requests certainly lowers overhead and can improve performance. It can also have benefits for caching, in that there can be fewer objects in the cache.
That said, this kind of optimization is only useful with metrics. There are profilers out there (Firebug has one) that can show you how many requests you're making and how long they take. You may (or may not) find there are more time-effective ways to increase performance and reduce load on your server.
I've been using Google PageSpeed to improve my site's performance. One of its recommendations is eliminating unused CSS in my app. Although a lot of the CSS is unused for a given page, it is used elsehwere in the app.
What's the right approach here? I'm considering creating a base CSS file for common CSS and then separate files for each individual page. Luckily there aren't that many pages. Is this overkill? And is there a better approach?
This is a Rails app, and I'm using asset_packager to minify my CSS and Javascript
Thanks!
Moe
It won't speed up your application because you will be adding new http requests, while if you pack all CSS into one file, that file will stay in the cache and you won't have to have an http-request for it for subsequent pages.
Google PageSpeed simply mean that you shouldn't provide styles you don't use anywhere in your application or only in pages that a user can't visit, for example the admin area.
As people in here mentioned, definitely not. You will just add new http requests. You should really keep in mind that pagespeed will probably always show that you have unused css on a given page, but that's not really a big issue.
Take a look at the other recommandations page speed is showing like enabling compression, optimizing the images (consider using css sprites if you aren't already) and more.
See also yahoo best practices to speed up your site.
That'll depend on the size of the file(s) and the way people use your site. If the file isn't huge to begin with and people will often go to many different pages, having page-specific css files will forfeit the benefit of caching, which is generally going to garner more benefit.
The overhead of an extra HTTP request to download yet another CSS file greatly outweighs the overhead of an extra few KB in the master CSS file.
I think it is best to componentise your stylesheets. For example, you might have a base css that provides the layout for your pages. Then you might have a theme css that provides colours, images, borders - visual elements. Then you might have separate css files for individual UI components, e.g. popup.css, calendar.css etc.
base.css
theme-blue.css
theme-blue-popup.css
theme-blue-calendar.css
This approach makes it easier to manage your styles (and switch them if you need to). More relevant to your question however, is that you now have the ability to specify what stylesheets are needed for each page on your site. Now if the user visits the homepage of your site only, and the homepage has no popups or calendars, then they haven't downloaded the styles for the components they aren't using. As they proceed further into the site, they will get the required stylesheets as and when they need them.
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Is there any advantage to having a single monster .css file that contains style elements that will be used on almost every page?
I'm thinking that for ease of management, I'd like to pull out different types of CSS into a few files, and include every file in my main <link /> is that bad?
I'm thinking this is better
positions.css
buttons.css
tables.css
copy.css
vs.
site.css
Have you seen any gotchas with doing it one way vs. the other?
This is a hard one to answer. Both options have their pros and cons in my opinion.
I personally don't love reading through a single HUGE CSS file, and maintaining it is very difficult. On the other hand, splitting it out causes extra http requests which could potentially slow things down.
My opinion would be one of two things.
1) If you know that your CSS will NEVER change once you've built it, I'd build multiple CSS files in the development stage (for readability), and then manually combine them before going live (to reduce http requests)
2) If you know that you're going to change your CSS once in a while, and need to keep it readable, I would build separate files and use code (providing you're using some sort of programming language) to combine them at runtime build time (runtime minification/combination is a resource pig).
With either option I would highly recommend caching on the client side in order to further reduce http requests.
EDIT:
I found this blog that shows how to combine CSS at runtime using nothing but code. Worth taking a look at (though I haven't tested it myself yet).
EDIT 2:
I've settled on using separate files in my design time, and a build process to minify and combine. This way I can have separate (manageable) css while I develop and a proper monolithic minified file at runtime. And I still have my static files and less system overhead because I'm not doing compression/minification at runtime.
note: for you shoppers out there, I highly suggest using bundler as part of your build process. Whether you're building from within your IDE, or from a build script, bundler can be executed on Windows via the included exe or can be run on any machine that is already running node.js.
A CSS compiler like Sass or LESS is a great way to go. That way you'll be able to deliver a single, minimised CSS file for the site (which will be far smaller and faster than a normal single CSS source file), while maintaining the nicest development environment, with everything neatly split into components.
Sass and LESS have the added advantage of variables, nesting and other ways to make CSS easier to write and maintain. Highly, highly recommended. I personally use Sass (SCSS syntax) now, but used LESS previously. Both are great, with similar benefits. Once you've written CSS with a compiler, it's unlikely you'd want to do without one.
http://lesscss.org
http://sass-lang.com
If you don't want to mess around with Ruby, this LESS compiler for Mac is great:
http://incident57.com/less/
Or you could use CodeKit (by the same guys):
http://incident57.com/codekit/
WinLess is a Windows GUI for comipiling LESS
http://winless.org/
I prefer multiple CSS files during development. Management and debugging is much easier that way. However, I suggest that come deployment time you instead use a CSS minify tool like YUI Compressor which will merge your CSS files into one monolithic file.
Historically, one of the main advantages x in having a single CSS file is the speed benefit when using HTTP1.1.
However, as of March 2018 over 80% of browsers now support HTTP2 which allows the browser to download multiple resources simultaneously as well as being able to push resources pre-emptively. Having a single CSS file for all pages means a larger than necessary file size. With proper design, I don't see any advantage in doing this other than its easier to code.
The ideal design for HTTP2 for best performance would be:
Have a core CSS file which contains common styles used across all pages.
Have page specific CSS in a separate file
Use HTTP2 push CSS to minimise wait time (a cookie can be used to prevent repeated pushes)
Optionally separate above the fold CSS and push this first and load the remaining CSS later (useful for low-bandwidth mobile devices)
You could also load remaining CSS for the site or specific pages after the page has loaded if you want to speed up future page loads.
You want both worlds.
You want multiple CSS files because your sanity is a terrible thing to waste.
At the same time, it's better to have a single, large file.
The solution is to have some mechanism that combines the multiple files in to a single file.
One example is something like
<link rel="stylesheet" type="text/css" href="allcss.php?files=positions.css,buttons.css,copy.css" />
Then, the allcss.php script handles concatenating the files and delivering them.
Ideally, the script would check the mod dates on all the files, creates a new composite if any of them changes, then returns that composite, and then checks against the If-Modified HTTP headers so as to not send redundant CSS.
This gives you the best of both worlds. Works great for JS as well.
Having only one CSS file is better for the loading-time of your pages, as it means less HTTP requests.
Having several little CSS files means development is easier (at least, I think so : having one CSS file per module of your application makes things easier).
So, there are good reasons in both cases...
A solution that would allow you to get the best of both ideas would be :
To develop using several small CSS files
i.e. easier to develop
To have a build process for your application, that "combines" those files into one
That build process could also minify that big file, btw
It obviously means that your application must have some configuration stuff that allows it to swith from "multi-files mode" to "mono-file mode".
And to use, in production, only the big file
i.e. faster loading pages
There are also some software that do that combining of CSS files at run-time, and not at build-time ; but doing it at run-time means eating a bit more CPU (and obvisouly requires some caching mecanism, to not re-generate the big file too often)
Monolithic stylesheets do offer a lot of benefits (which are described in the other answers), however depending on the overall size of the stylesheet document you could run into problems in IE. IE has a limitation with how many selectors it will read from a single file. The limit is 4096 selectors. If you're monolithic stylesheet will have more than this you will want to split it. This limitation only rears it's ugly head in IE.
This is for all versions of IE.
See Ross Bruniges Blog and MSDN AddRule page.
There is a tipping point at which it's beneficial to have more than one css file.
A site with 1M+ pages, which the average user is likely to only ever see say 5 of, might have a stylesheet of immense proportions, so trying to save the overhead of a single additional request per page load by having a massive initial download is false economy.
Stretch the argument to the extreme limit - it's like suggesting that there should be one large stylesheet maintained for the entire web. Clearly nonsensical.
The tipping point will be different for each site though so there's no hard and fast rule. It will depend upon the quantity of unique css per page, the number of pages, and the number of pages the average user is likely to routinely encounter while using the site.
I typically have a handful of CSS files:
a "global" css file for resets and global styles
"module" specific css files for pages that are logically grouped (maybe every page in a checkout wizard or something)
"page" specific css files for overrides on the page (or, put this in a block on the individual page)
I am not really too concerned with multiple page requests for CSS files. Most people have decent bandwidth and I'm sure there are other optimizations that would have a far greater impact than combining all styles into one monolitic CSS file. The trade-off is between speed and maintainability, and I always lean towards maintainability. The YUI comperssor sounds pretty cool though, I might have to check that out.
I prefer multiple CSS files. That way it is easier to swap "skins" in and out as you desire. The problem with one monolithic file is that it can get out of control and hard to manage. What if you want blue backgrounds but don't want the buttons to change? Just alter your backgrounds file. Etc.
Maybe take a look at compass, which is an open source CSS authoring framework.
It's based on Sass so it supports cool things like variables, nesting, mixins and imports. Especially imports are useful if you want to keep seperate smaller CSS files but have them combined into 1 automatically (avoiding multiple slow HTTP calls).
Compass adds to this a big set of pre-defined mixins that are easy for handling cross-browser stuff.
It's written in Ruby but it can easily be used with any system....
here is the best way:
create a general css file with all shared code
insert all specific page css code into the same page, on the tag or using the attribute style="" for each page
on this way you have only one css with all shared code and an html page.
by the way (and i know that this is not the right topic) you can also encode your images in base64 (but you can also do it with your js and css files). in this way you reduce even more http requests to 1.
SASS and LESS make this all really a moot point. The developer can set up effective component files and on compile combine them all. In SASS you can toggle off the Compressed Mode while in development for easier reading, and toggle it back on for production.
http://sass-lang.com
http://lesscss.org
In the end a single minified CSS file is what you want regardless of the technique you use. Less CSS, Less HTTP requests, Less Demand on the server.
The advantage to a single CSS file is transfer efficiency. Each HTTP request means a HTTP header response for each file requested, and that takes bandwidth.
I serve my CSS as a PHP file with the "text/css" mime type in the HTTP header. This way I can have multiple CSS files on the server side and use PHP includes to push them into a single file when requested by the user. Every modern browser receives the .php file with the CSS code and processes it as a .css file.
You can just use one css file for performance and then comment out sections like this:
/******** Header ************/
//some css here
/******* End Header *********/
/******** Footer ************/
//some css here
/******* End Footer *********/
etc
I'm using Jammit to deal with my css files and use many different files for readability.
Jammit doest all the dirty work of combining and compressing the files before deployment in production.
This way, I've got many files in development but only one file in production.
A bundled stylesheet may save page load performance but the more styles there are the slower the browser renders animations on the page you are on. This is caused by the huge amount of unused styles that may not be on the page you are on but the browser still has to calculate.
See: https://benfrain.com/css-performance-revisited-selectors-bloat-expensive-styles/
Bundled stylesheets advantages:
- page load performance
Bundled stylesheets disadvantages:
- slower behaviour, which can cause choppyness during scrolling, interactivity, animation,
Conclusion:
To solve both problems, for production the ideal solution is to bundle all the css into one file to save on http requests, but use javascript to extract from that file, the css for the page you are on and update the head with it.
To know which shared components are needed per page, and to reduce complexity, it would be nice to have declared all the components this particular page uses - for example:
<style href="global.css" rel="stylesheet"/>
<body data-shared-css-components="x,y,z">
I've created a systematic approach to CSS development. This way I can utilize a standard that never changes. First I started with the 960 grid system. Then I created single lines of css for basic layouts, margins, padding, fonts and sizes. I then string them together as needed. This allows me to keep a consistent layout across all of my projects and utilize the same css files over and over. Because they are not specific. Here's an example: ----div class="c12 bg0 m10 p5 white fl"/div--- This means that the container is 12 columns across, utilizes bg0 has margins of 10px padding of 5 the text is white and it floats left. I could easily change this by removing or adding a new - What I call a "light" style- Instead of creating a single class with all these attributes; I simply combine the single styles as I code the page. This allows me to create any combination of styles and does not limit my creativity or cause me to create a massive number of styles that are similar. Your style sheets become a lot more manageable, minimized and allow you to re-use it over and over. This method I have found to be fantastic for rapid design. I also no longer design first in PSD but in the browser which also saves time. In addition because I have also created a naming system for my backgrounds and page design attributes I simply change out my image file when creating a new project.(bg0 = body background according to my naming system) That means that if I previously had a white background with one project simply changing it to black simply means that on the next project bg0 will be a black background or another image..... I have not found anything wrong with this method yet and it seems to work very well.
Just wanted to get a few opinions really, I'm trying to increase the loading speed of my site, and one way that Google pagespeed has suggested is to remove the unused CSS from my CSS file for each page.
At the moment I am using one master CSS file for every page on the site.
My question is would having individual CSS files for each page make overall loading times quicker ? I guess the first page would load quicker, but then each page would have a different CSS file which could potentially end up taking longer over a whole site visit ?
Also pagespeed seems to warn against including multiple CSS files so I guess I can't really 'layer' them up...
If the CSS file is cached then including multiple files will not be an advantage.
Note
For performance rules regarding CSS you can
Try minifying your CSS
Optimize CSS Sprites
Avoid Filters
Avoid CSS Expressions
For more detailed reading go through this
Best Practices for Speeding Up Your Web Site
There are two optimisation directives that contradict each other in this case. Of course you should reduce the size of the files if possible, but you should also have as few requests as possible. Using a global style sheet reduces the number of requests, but it means a larger file.
You just have to look into where your needs are. If you need to reduce the initial load time, you should move styles out of the global style sheet. If you need to reduce the number of requests, you should use a global style sheet rather than individual page style sheets.
Download and install YSlow, it will give you an accurate picture of how fast your page is as well as practical steps to improve performance.
I wouldn't worry about it too much. Run your CSS through a filter to strip comments and whitespace, be aware of small shortcuts like padding: 1em 3em .5em 5px etc, make sure the file is being cached properly, and sent from your server with gzipping, and you'll be fine. CSS is usually such a small fraction of the payload, it's not worth losing sleep over.
The only time where I'd split up a CSS file (for delivery to the client) would be if there were large sections of my site which called for unique styles where most people would never venture: eg, an administration section.
Do a little thinking about how the typical user will use your sight. If (like many sites) the average user only views a single page before moving on, then having dedicated CSS files for each page may just be worth it.
However, in the vast majority of cases, a single css file would definitely be the preferred solution
CSS files are cached by browsers anyway, so either you have a single file or many split, it won't matter after all of them got loaded on the first use.
Use just one CSS for all pages. Once your css is cached then there will be no overhead of downloading that css again and again.
Also, ad adam said Minify your css
DustMeSelectors is the extension you need. It will go through all of your site (and providing all of these are inter-linked) will fetch which selectors in your css are not used anywhere.