Recently we have experienced the problem of browsers caching the css files, so that when we move code to another web server we get unexpected and unwanted results.
Having read various solutions it occurred to me that the css file could be included in the template. Rather than write
<link href="/static/css/parentx.css" rel="stylesheet" type="text/css">
we could put
<style>{% include "static/css/parent.css" %}</style>
which would embed the css in the html. It has the added benefit of reducing the number of calls back to the server for the css file but the disadvantage of not caching the css at all and not allowing the web server to provide the static files. However, these files are quite small, typically about 12K.
I propose this as a temporary measure as I have just discovered the existence of asset management plugins that look to do a better job.
I have never seen the use of the 'include' template command to get css (and javascript) files so perhaps there is a drawback of which I am unaware?
Not caching the CSS file at all will slow page loading though it's unnecessary.
Cache your CSS as long as possible and necessary and when you need to invalidate cache, a sure way is to load another file, I mean the same file with another name. It could be parent1391234565.css or parent-v003.css or parent130307.css or parent-4e6ca1437f2d.css. If you told browsers to download parent-v002.css, you're pretty certain they don't have parent-v003.css in their cache!
Related
I'm Building a website, and It has a lot of pages approximately like 30 pages, and I linked these pages with one CSS file (the main css files) not to mention the other files such as bootstrap.min.css and other plugins that requires their own css files.
My point is that in all of these I'm using like the same css files, but in some pages I don't need all of the properties and styles in main.css file, so I'm thinking that I split that css file into multiple files, and create file called (global.css) and type in the properties that I'll need in all pages, and make another css file for each individual page.
My question is:-
Is it going to be helpful for the website speed if I split that main css into multiple css files and include only the necessary things for each page?
Ideally you want to abstracts your CSS files into many different SCSS files and then compiles them into one minified master file. One file for the header styling, one for links, one for typography. I was afraid of SCSS but now love it... Nothing changes in production, you are still running off CSS bit in development you are just making your life that little bit more organised.
NO,
you better dont want to do that if your code is small like less that 50kb or even 100kb
also if you provide seperate css for each page browser has to download each css file when user visit that page that will cost you one additional request for every single page this will slow down your page and affect your performace
instead I would suggest when your code goes live compress your code or minified it so youll get the more smaller version of your code
I also suggest to leverage browser caching (using .htaccess if you are using linux server)
above are the things which comes under front end performance improvement
I have an app which needs to work in several languages, and several different color schemes and I would rather not load all the CSS every time since a large amount of it is not necessary or relavant (rtl css for example) but meteor automaticaly loads all CSS files he can find.
is there a way to selectively load CSS files?
Thanks.
If you place a CSS file within the reach of Meteor compiler, it's merged into the main app and in the current release there's nothing you can do about this.
You can however put the file in /public directory. Meteor won't touch it there, and you will be able to load it at will by adding <link/> tag to your page head.
Please have a look at https://stackoverflow.com/a/26694517/1523072 which seems a quite elegant way to do this and also explains why you shouldn't do it.
One of my apps currently loads 2.6MB compressed Javascript and 300KB compressed CSS, which seems like a lot. However, after the first visit all the resources are cached by my browser, which means the only thing that is transferred between browser and server after that is pure data.
Since External Style Sheet will be kept in cache, so it will be faster for page load with frequenly visit.Should i always using external style sheet instead of embedded style sheet even if a style is used only for one particular page. The only drawback i can think of is if we use only external style sheet we might have a lot of file in folders styles and this can be messy and confused for others fellow developer compared with using embedded style sheet for css that use only on that page.
If it's for one page, and only that page, then no. You'll induce an unnecessary GET request on your server to grab that CSS file.
Edit: To answer the question in your comment "Will using an external CSS document have an overhead of a GET request?" the answer is yes. For each file not included in the HTML document you're accessing (i.e. external javascript files, images, external stylesheets, etc) the client's browser will have to make another GET request to attain those files.
An embedded CSS is included in the first GET response for that page (it is part of the HTML response, after all).
In external style-sheet case scenario, you'd be imposing two GET requests (one for the HTML document, and another for the CSS file) as opposed to the single GET request to just embed the CSS into your document.
See the wiki on HTTP for more information: http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_message
HTTP requests are costly as far as speed goes. I'd try to minimize them. For organization sake, try to keep things in external stylesheets, but if it's just a couple of things applicable to only that page, it makes sense to use an embedded stylesheet. You have to find the right balance of the two.
We can write CSS as the following types:
Inline CSS
Embedded CSS
External CSS
I would like to know pros and cons of each.
It's all about where in the pipeline you need the CSS as I see it.
1. inline css
Pros: Great for quick fixes/prototyping and simple tests without having to swap back and forth between the .css document and the actual HTML file.
Pros: Many email clients do NOT allow the use of external .css referencing because of possible spam/abuse. Embedding might help.
Cons: Fills up HTML space/takes bandwidth, not resuable accross pages - not even IFRAMES.
2. embedded css
Pros: Same as above regarding prototype, but easier to cut out of the final prototype and put into an external file when templates are done.
Cons: Some email clients do not allow styles in the [head] as the head-tags are removed by most webmail clients.
3. external css
Pros: Easy to maintain and reuse across websites with more than 1 page.
Pros: Cacheable = less bandwidth = faster page rendering after second page load
Pros: External files including .css can be hosted on CDN's and thereby making less requests the the firewall/webserver hosting the HTML pages (if on different hosts).
Pros: Compilable, you could automatically remove all of the unused space from the final build, just as jQuery has a developer version and a compressed version = faster download = faster user experience + less bandwidth use = faster internet! (we like!!!)
Cons: Normally removed from HTML mails = messy HTML layout.
Cons: Makes an extra HTTP request per file = more resources used in the Firewalls/routers.
I hope you could use some of this?
I'm going to submit the opinion that external style sheets are the only way to go.
inline CSS mixes content with presentation and leads to an awful mess.
embedded CSS gets loaded with every page request, changes cannot be shared across pages, and the content cannot be cached.
I have nothing against either method per se, but if planning a new site or application, you should plan for external style sheets.
Inline
Quick, but very dirty
This is (sadly) also the only really sane option for HTML formatted email as other forms often get discarded by various email clients.
Embedded
Doesn't require an extra HTTP request, but doesn't have the benefits of:
Linked
Can be cached, reused between pages, more easily tested with validators.
You want external css. It's the easiest to maintain, external css also simplifies caching. Embedded means that each separate html file will need to have it's own css, meaning bigger file size and lots of headaches when changing the css. Inline css is even harder to maintain.
External css is the way to go.
Where to start!!??
Say you had a site with 3 pages...
You could get away with Inline CSS (i.e. CSS on the page itself, within tags).
If you had a 100 page website...
You wouldn't want to change the CSS on each page individually (or would you?!)...
So including an external CSS sheet would be the nicer way to go.
Inline CSS is generally bad. It's much easier to modify the style of a page when all the styles are located in one central location, which inline CSS doesn't offer. It's easy for quickly prototyping styles, but shouldn't be used in production, especailly since it often leads to duplicating styles.
Embedded CSS centralizes the styles for the page, but it doesn't allow you to share styles across pages without copying the text of the embedded style and pasting it in each unique page on your site.
External CSS is the way to go, it has all of the advantages of embedded CSS but it allows you to share styles accross multiple pages.
Use external CSS when:
you have a lot of css code that will make your file messy if you put it all inline
you want to maintain a standard
look-and-feel across multiple pages
External CSS makes it a lot easier to manage your CSS and is the accepted way of implementing styles.
If the styles are only needed for one file, and you don't foresee that ever changing to apply to other pages, you can put your css at the top of the file (embedded?).
You should generally only use inline CSS if:
It's a one-time formatting for a specific tag
You want to override the default css (set externally or at the top of the file) for a specific tag
To everyone in the here and now, reading after 2015, with projects like Polymer, Browserify, Webpack, Babel, and many other important participants that I'm probably missing, we have been ushered into a new era of writing HTML applications, with regards to how we modularize large applications, distribute changes and compose related presentation, markup and behavior into self-contained units. Let's not even get started with service workers.
So before anyone forms an opinion on what is and isn't feasible, I would recommend that they investigate the current web ecosystem in their time to see if some issues related to maintainability have been gracefully solved.
Pros:
Allows you to control the layout of the entire site with one file.
Changes affect all documents at the same time.
Can eliminate redundant in-line styling (Font, Bold, Color, Images)
Provide multiple views of the same content for different types of users.
Cons:
Older browsers may not be able to understand CSS.
CSS is not supported by every browser equally.
In this case, the pros far outweigh the cons. In fact, if the site is designed in a specific way, older browsers will display the content much better (on average) than if the site were managed with tables.
If you are using a server side language, why not embed CSS and use conditional programming to display it as necessary? For example, say you're using PHP w/ Wordpress and you want some homepage specific CSS; you could use the is_home() function to show your CSS in the head of the document for that page only. Personally, I have my own template system that works like so:
inc.header.php = all the header stuff, and where page specific CSS would go I put:
if(isset($CSS)) echo $CSS;
Then, in a specific page template (say about.php), I would use a heredoc variable for the page specific CSS, above the line which includes the header:
Contents of about.php:
<?php
$CSS = <<< CSS
.about-us-photo-box{
/* CSS code */
}
.about-us-something-else{
/* more CSS code */
}
CSS;
include "inc.header.php"; // this file includes if(isset($CSS)) echo $CSS; where page-specific CSS would go ...
<body>
<!-- about us html -->
include "inc.footer.php";
?>
Is there something I'm missing that makes this approach inferior?
Pros:
1) I can still cache the page using standard caching techniques (is there a caching method that takes advantage of a CSS only external file??).
2) I can use php for special case conditional formatting in specific class declarations if absolutely necessary (PHP doesn't work in a CSS file, unless I'm missing some server directive I could set).
3) All my page specific CSS is extremely well organized in the actual PHP file in which it's being used.
4) It cuts down on HTTP requests to external files.
5) It cuts down on server requests to external files.
Cons:
1) My IDE program (Komodo IDE) can't follow the Heredoc formatting to properly highlight the CSS, which makes it slightly harder to debug syntax errors in the CSS.
2) I really can't see any other con, please enlighten me!
Which is a better option: to store CSS on a separate file or on the same page?
Let's forget the fact that changing the CSS on a file makes it to apply all HTML pages directly. I am using dynamic languages to generate the whole output - so that does not matter.
A few things I can think of:
CSS on a separate file generates less bandwidth load.
CSS on a separate file needs another HTTP request.
On the other hand, if I compress the data transmission with Zlib, the CSS on the same page should not matter in terms of bandwidth, correct? So, I get one less HTTP request?
The main benefit of an external CSS file is that:
It can be used on multiple pages; and
It can be cached so it doesn't need to be loaded on every page.
So, if there is potential for reuse of the dynamically generated CSS between pages or on multiple views of the same page then an external file could add value.
There are several common patterns for dynamically generated CSS.
1. Generating a subset for a page
I've seen this occasionally. A developer decides to limit the amount of CSS per page by only sending what's necessary. I don't imagine this is the case for you but I'm mentioning it for completeness. This is a misguided effort at optimization. It's cheaper to send the whole lot and just cache it effectively.
2. User-selected theme
If the user selects a particular look for your site, that's what I'm talking about. This implies they might select a whole package of CSS and there might be a limited set to choose from. Usually this will be done by having one or more base CSS files and then oen or more theme CSS files. The best solution here is to send the right combination of external CSS files by dynamically generating the page header with the right <link> elements and then caching those files effectively.
3. User-rolled theme
This goes beyond (2) to where the user can select, say, colours, fonts and sizes to the point where you can't package those choices into a single theme bundle but you have to generate a set of CSS for that user. In this case you will probably still have some common CSS. Send that as an external CSS files (again, caching them effectively).
The dynamic content may be best on the page or you may still be able to make use of external files because there is no reason a <link> can't point to a script instead of a static file. For example:
<link rel="stylesheet" href="/css/custom.php?user=bob" type="text/css">
where the query string is generated dynamically by your header from who is logged in. That script will look up the user preferences and generate a dynamic CSS file. This can be cached effectively whereas putting it directly in the HTML file can't be (unless the whole HTML file can be cached effectively).
4. Rules-based CSS generation
I've written a reporting system before that took a lot of rules specified by either the user or a report writer and a custom report and generated a complete HTML page (based on the tables and/or charts they requested in the custom report definition) and styled them according to the rules. This truly was dynamic CSS. Thing is, there is potential for caching here too. The HTML page generates a dynamic link like this:
<link rel="stylesheet" href="/css/report.annual-sales.0001.css" type="text/css">
where 'annual-sales' is the report ID and 0001 is like a version. When the rules change you create a new version and each version for each report can be cached effectively.
Conclusion
So I can't say definitively whether external CSS files are appropriate or not to you but having seen and developed for each of the scenarios above I have a hard time believing that you can't get some form of caching out of your CSS at which point it should be external.
I've written about the issue of effective CSS in Supercharging CSS in PHP but the principles and techniques apply in any language, not just PHP.
You may also want to refer to the related question Multiple javascript/css files: best practices?
There is a method that both Google and Yahoo apply which benefit's from inline CSS. For the very first time visitors for the sake of fast loading, they embed CSS (and even JavaScript) in the HTML, and then in the background download the separate CSS and JS files for the next time.
Steve Souders (Yahoo!) writes the following:
[...] the best solution generally is
to deploy the JavaScript and CSS as
external files. The only exception
I’ve seen where inlining is preferable
is with home pages, such as Yahoo!'s
front page (http://www.yahoo.com) and
My Yahoo! (http://my.yahoo.com). Home
pages that have few (perhaps only one)
page view per session may find that
inlining JavaScript and CSS results in
faster end-user response times.
If you're generating HTML dynamically (say, from templates), embedding CSS allows you the opportunity to also generate the CSS dynamically using the same context (data, program state) as you have when you're producing the HTML, rather than having to set that same context up again on a subsequent request to generate the CSS.
For example, consider a page that uses one of several hundred images for a background, depending on some state that's expensive to compute. You could
List all of the several hundred images in rules in a seperate, static CSS file, then generate a corresponding class name in your dynamic HTML, or
Generate the HTML with a single class name, then on a subsequent request generate CSS with a rule for that name that uses the desired image, or
Do (2), but generate the CSS embedded in the HTML in a single request
(1) avoids redoing the expensive state computation, but takes a larger hit on traffic (more packets to move a much larger CSS file). (2) Does the state calculation twice, but serves up a smaller CSS file. Only (3) does the state calculation once and serves the result in a single HTTP request.
Browsers can cache the CSS files (unless it changes a lot). The bandwidth should not change, because the information is sent, no matter where you put it.
So unless the css quite static, putting it in the page costs less time to get.
I always use mix of both.
site-wide styles are in separate file (minified & gzipped),
any page-specific styles are put in <style> (I've set up my page templates to make it easy to insert bits of CSS in <head> easily at any time).
Yes and no. Use a .css file for most rules; your site should have a consistent look anyway. For rare, special case, or dynamically generated rules you can use inline 'style=""'. Anything that sticks should move into the .css, if only to make transcluding, mash-ups, etc. easier.
Keep it separate. HTML for centent, CSS for style, JavaScript for logic.