The look of a page printed by plone is ok and neutral thanks print.css.
It would be rather handy to have a diazo rule which switchs off theming in the case that the page is printed (that the demanding device is a printer).
<notheme if="$print" />
But how to define $print in manifest.cfg?
Unless you want to have a specific print URL, that won't work. print.css works at the browser/css level. The server doesn't even know, and the page isn't even reloaded.
I think the general consensus is that CSS is the right way to do this. So, stick with that strategy unless you have very unusual requirements.
Related
I am using google's audit and its tells me to remove unused CSS. I don't know if that css is for just that page or the whole site. The CSS might be there but not needed on that page but another page. Can someone tell me how this works?
It is telling you to remove unneeded CSS for that page.
However you have rightly pointed out the flaw in this suggestion as it only takes into account the current page (in it's initial state, obviously if you have a pop-out menu it won't gather the CSS for that).
Think of it more as a guideline of making sure you don't send the whole of Bootstrap just for the grid and column layouts for example.
Overall this is very difficult to fix, just use the coverage section on the performance tab in Developer tools to make sure you don't have any massively bloated CSS files and you will be fine.
Obviously reduce your unused CSS if it is easy to do so.
The only other thing that this point covers (in it's description, not as part of it's monitoring) is deferring non-essential CSS.
You should defer any Style Sheets that are not required for rendering 'above the fold' content (and inline your 'above the fold' CSS).
This point is also covered in 'Eliminate Render Blocking Resources' so I never quite get why they add the suggestion under this part as well but I have added it for completeness.
I find this rule was good at guiding me when designing a theme from the ground up as it made me seperate global CSS and page CSS more effectively.
Unless your site is scoring 98 / 100 (or you have hundreds of kilobytes of CSS) and you want to squeeze that last little bit of performance out of the site, simply minify and combine your CSS files and ignore this point.
Google's audit tool compares the entire stylesheet against the current URL and then tells you how much of it is actually not used by the browser.
The browser however still needs to download the entire file and then match all CSS selectors that apply to the current URL.
There are many ways to deal with this, but I find it the easiest to use an external API tool like Splitcss that does this for you on URL basis.
If you have only a few URL patterns in your web application, you can use some CLI tools like purgecss or uncss.
Currently I'm using Modernizr on all my sites and it turns out because of how it works it requires unsafe-inline styles to be allowed. I am already not allowing inline scripts and unsafe-eval for scripts. Curious as to what security risks there are for allowing inline styles?
Allowing inline styles makes you susceptible to a the "other XSS". Cross Site Styling attacks.
The idea here is that any places where a user can inject a style attribute into your document they can modify the appearance of your page any way they want. I'll list a couple potential attacks ordered by increasing severity:
They could turn your page pink, and make it look silly.
They could modify the text of your page, making it look like you're saying something offensive that could offend your readership audience.
They could make user generated content, like a link they provided appear outside of the normal places where people expect to see user content, making it appear official. (eg, replacing a "Login" button on your site with their own link).
Using a carefully crafted style rules they could send any information included on the page to external domains and expose or otherwise use that data maliciously against your users.
The fourth example, with the information being leaked to external domains could be entirely prevented in spite of the unsafe-inline provided you ensure your other CSP rules never allow any kind of request to go to a untrusted or wildcard domain. But the first 3 will always be possible if you miss blocking a style attribute somewhere.
Mike West did a good talk on this for CSSConf a few years back for some more examples.
Personally I find not using unsafe-inline for CSS is impractical. It means I have to use an external style sheet file for EVERY style. Coloring text, centering text etc. It can be done. You can do this by using a main style sheet "main.css" and a file sheet for every page ("index.css", "contect.css", etc). However I am not so stupid that I allow arbitrary code execution; I filter out all less then and grater then signs. I find this to be an unreasonable restriction. Blocking inline JavaScript is not as bad as blocking inline CSS. I can see blocking inline JavaScript. However I don't think I will do that ether. If you are careful to filter your less then and grater then signs (there are some other stupid things you can do besides not filtering these) if you don't make stupid mistakes that allows arbitrary code execution then you are safe. These inline blocks are only created to protect web developers that screw up there code in a way that allows arbitrary code execution. But the blocks make it a bit harder to code. So it's a trade off.
TLDR IMHO not worth blocking inline CSS, worth blocking inline JavaScript but unnecessary. I will NOT consider blocking inline CSS, I am not going to block inline JavaScript but I might consider it.
Experience: I am a web designer that designs in code using HTML CSS JavaScript and PHP. I have my own website that I coded by hand. And I validate with the official w3 validator. I keep up with web design standards like HTML5.
I'm building a site with a lot of similar css between pages. I've decided that a good approach would be to have the css generated as strings by php functions (with parameters) and outputed as an internal stylesheet in every page that i serve. The benefits:
this way if i make a change it will reflect throughout the entire site without having to maintain duplicates
i can send only the necessary css for a certain page
it's better than having small css files and sending a lot of css headers at inclusion
the possibility that the content might be displayed before the stylesheet is loaded is gone
i can calculate dimensions by using parameters
i can create a layer that will minify the result received from these functions or serve cached minified css
I haven't seen this done anywhere else unfortunately so i'm thinking that this might be because of SEO. The generated internal stylesheet will be at around 15kb max (before minifying the stylesheet).
I need your opinion on this approach and your thoughts about the impact a long internal stylesheet will have on SEO.
Many thanks.
Not an answer to your question (which is interesting enough!), but most of your arguments for inline CSS are wrong. An external style sheet is always the better and faster solution.
The first point you can handle by adding a version number to the style sheet's file name
The second point is moot because an external file gets cached, so no additional requests
The third point is moot for the same reason
The fourth point won't really matter once the style sheet is cached
The fifth point can be sorted using inline CSS for only the properties that need to be
updated dynamically - usually a tiny fraction of the whole CSS code base
The sixth point I don't get.
Go for an external style sheet. Just make sure it gets served with the correct caching headers!
Like long blocks of inline JavaScript, they are ignored.
Bots look at the content, not the layout. If you want a better representation of what they see, try the Lynx browser.
Unfortunately they will not be cached on the user's browser either, as external CSS and JS are, making each page load slower. It is actually more efficient to have a large external stylesheet than server up related "css snippets" with each page.
Assuming by 'internal stylesheet' you mean inline CSS included using the <style> tag, I'd recommend against this. If you use an external stylesheet, visitors download it once on the first request, and it will then be cached. By including all of your CSS inline, you're adding page weight to every single HTML request.
Although it might seem more efficient to just serve CSS for the current page, or split your CSS into lots of different page-specific stylesheets; in practice it's usually better just to have one stylesheet. Serving this compressed and with appropriate expires headers will almost always be faster than the alternatives.
Regarding SEO, robots ignore CSS, so this won't have any affect. If you had so much CSS that it substantially slowed down loading of your page, in theory you might start having issues, but you would need an inhuman amount of inline CSS before this could even potentially be an issue.
To the extent of my knowledge, your CSS sheet plays a minimal role in SEO, what is more important is your HTML markup and execution.
Following the order of '< h1 > - < h5 >' for your heading tags, with accompanying '< p >' tags instead of '< font >' or similar approaches is what will effect a web crawlers ability to recognise and prioritise the content in your page.
While you can use CSS to hide paragraph that you only want to appear in search engines and similar techniques it has little importance compared to the HTML structure.
All benefits you said apply. Search engines doesn't care too much about CSS and javascript (of course, if your page takes too long to wrap and send, this will affect, but I don't think it is the case).
I've seen this kind of solution before, but people tend to avoid use scripting to serve, once you can use media queries instead, writing just only one external stylesheet. I think you should take a look on this.
However, I see you are trying to optimize the CSS sent. This is good, but talking about 80k for all sheets, makes me think if you are not over complicating the rules.
Well, as last opinion, you can cache many different responses and make use of "canonical" thing on page head.
Is there any problem with using jquery layout plugin (there are several) to layout a page as opposed to using CSS and fixing browser compatibility issues myself?
Another problem is that the page has to fully load and download the javascript, then get rendered. This will slow down the page significantly.
The most obvious problem is that any visitor to the page using a browser with JavaScript turned off will not get the layout. If you're willing to turn away from those people, that may not be a blocking factor for you.
There can also be performance issues, delays on resizing the browser window, that sort of thing.
I'm not saying don't do it; if it's appropriate for your target audience. But look to see if you can avoid it or at least gracefully degrade if JavaScript isn't enabled. (Turn off JavaScript and come here to SO, for instance; still very usable in a read-only way.)
If doing this, continue to be sure to mark up your content in the main page (rather than only adding it dynamically) and use the most semantic markup you can, to improve your search-ability.
When your layout doesn't behave for whatever reason (and that will happen), will you be able to understand the code behind the JQuery plugin to fix it?
Invest in yourself and learn CSS properly, it's not hard, it doesn't take long and it will equip you for the future, don't just rely on plugins. Now I'm not saying never use a plug-in, but this to me seems inappropriate use
Our Dev team had been developing enterprise web page more than 2 years ago. We are curious to know what is the best way to write a contract for CSS usage. For example, if we have a COMP, how we agree on a contract so our developers and our designers agree and we don't have to go back.
Is there a tool that is available for this type of technical writing?
What is the threadhold of information put in the CSS versus on the HTML page? Some of our designers thing that some things should go directly into the HTML page. The general opinion is that everything that is style should go in a CSS and all else in the html.
Thanks for your input.
Well, if a webpage has very specific CSS just for itself, I guess there is an argument for defining the CSS in the page, otherwise I would always have the CSS in an external file.
Try to avoid or at least minimise in-lining the CSS as a style attribute on HTML elements though, that would be a PITA to manage.
Most pages will be template driven with standard content styles, and thus the CSS styles will be defined in external files.
One thing you might want to think about are the number of CSS files - some people suggest that you should minimise this to just one file site-wide or per-template (or area of the site) to minimise HTTP requests to the server and avoid delayed CSS loading and funny looking styling up until that point.
So this "contract for CSS usage" is actually just a coding standard for HTML pages?
I'm a purist, so for me HTML is for content and structure and CSS is for layout & styling. That's really what each of them were created for.
See CSS Zen Garden for a great example of this. Same HTML and hundreds of different layouts & designs.
What are the reasons your designers give for styling to be in the HTML?
Edit: The main goal here is consistency across the site, correct? The more you have abstracted away from each page, the fewer changes you'll have to make.
The idea that the HTML should merely encode information and not style is called semantic markup. It has several advantages that you already know about, like separation of concerns, and a few that you probably haven't thought about.
If you stick to the web standards and separate your style and content you will also end up with a page that is more accessible to those with disabilities.
If you need to have some things styled differently for a specific page, use separate CSS include file for that page only and then use a CSS class on the element you want to style.
If I have style that is for a one time, single use page, I will consider putting it in the header of that page, as my templating system allows for that.
However you should never use inline styles. Even if you do a page with a block in it for a one off. That way should you find that you "one time" item becomes a site wide style, you can simply move the CSS into the external CSS file and not edit the content.