#penthouse
Critical Path CSS Generator
Penthouse is a tool generating critical path css for your web pages and web apps in order to speed up page rendering. Supply the tool with your site's full CSS, and the page you want to create the critical CSS for, and it will return all the CSS needed to render the above the fold content of the page. Read more about critical path css here.
The process is automatic and the generated css should be ready for production as is. If you run in to problems however, check out the Problems section further down on this page.
Penthouse can be used directly from the command line, as a Node module, or via the online version.
Install PhantomJS first, and make sure it works for you. Then download the penthouse.js file.
phantomjs penthouse.js [URL to page] [CSS file] > [critical path CSS file]
//for example
phantomjs penthouse.js http://mySite.com/page1 allStyles.css > page1-critical-styles.css
phantomjs penthouse.js http://mySite.com/page2 allStyles.css > page2-critical-styles.css
To run on HTTPS pages two extra flags must be passed in, directly after phantomjs in the call:
--ignore-ssl-errors=true --ssl-protocol=tlsv1
//as such:
phantomjs penthouse.js --ignore-ssl-errors=true --ssl-protocol=tlsv1 [URL to page] [CSS file] > [critical path CSS file]
By default penthouse gives you the css needed to render a viewport of size 1300x900. This css will cover all smaller viewport sizes, unless you're delivering a different DOM or doing something crazy. You can pass in your a different viewport width and viewport height if you want; these two params must follow the [CSS file] like this:
phantomjs penthouse.js [URL to page] [CSS file] [Viewport WIDTH] [Viewport HEIGHT] > [critical path CSS file]
npm install --save-dev penthouse
This will add penthouse to the list of dependencies
Require as normal and execute with a callback
var penthouse = require('penthouse'),
path = require('path');
penthouse({
url : 'http://google.com',
css : path.join(__basedir + 'static/main.css'),
width : 400, // viewport width
height : 240 // viewport height
}, function(err, criticalCss) {
console.log(criticalCss);
});
http://jonassebastianohlsson.com/criticalpathcssgenerator/
###Background images missing
Change any relative paths (f.e. background-image: url("../images/x.gif");) to absolute background-image: url("http://mysite.com/images/x.gif");, and then try again.
###Unstyled content showing
The most common problem is with clearing floats. Instead of clearing elements appearing after floated elements (f.e. using clear:both;), clear the floats themselves by using the clear-fix pattern. Float clearing will now work also in the generated critical css.
If you for some reason have an element appearing early in the DOM, but that you apply styles to move outside of the above the fold content (using absolute position or transforms), consider whether it really should appear so early in the DOM.
###Special glyphs not showing/showing incorrectly
Problems with special characters like → after converting? Make sure you use the correct hexadecimal format in your CSS. You can always get this format from your browser console, by entering '→'.charCodeAt(0).toString(16) (answer for this arrow glyph is 2192). When using hexadecimal format in CSS it needs to be prepended with a backslash, like so: \2192 (f.e. content: '\2192';)
###Other problems Please report your issue (check that it's not already there first though!), and I will try to fix it as soon as possible.
2014-06-10 v0.2.0 Node module and standalone executable (@fatso83) 2014-06-05 v0.1.0 Published on NPM (@pocketjoso) 2014-06-04 v0.0.0 PhantomJS script /core logic (@pocketjoso)