Inline SCSS with Jekyll and GitHub Pages
If you stay up-to-date on website performance then you’ve probably heard of the critical path and reducing the time it takes for a browser to start rendering a page. One of the most important things we can do is to remove render-blocking requests.
The browser can’t start rendering anything until external CSS files have been loaded. Google recommends inlining above-the-fold CSS. So any CSS that styles content above-the-fold should be inlined in the
<head> tag, and any non-critical CSS should be loaded asynchronously, so it doesn’t block the rendering of the page.
If you’re using plain CSS files, this is very simple. Place
critical.css in the
_includes directory, and then do:
If, however, you’re using SCSS or SASS files, this has been impossible without using plugins, which aren’t allowed on GitHub Pages. That bugged me, so I wrote a couple of Liquid filters for Jekyll. As of Jekyll 2.3.0, there are two new filters:
scssify. These work in the same way that
markdownify does. Pass it some SASS or SCSS and they’ll return CSS.
We can use these filters to inline our SCSS like so:
If you have a small stylesheet and can inline all of it without your page exceeding 14kb, then you’re good to go. If you have a bigger stylesheet, you’ll want to load the rest of your stylesheet asynchronously later. Scott Jehl wrote a great script for loading CSS asynchronously.
This is a super easy way to speed up your site speed, and especially the perceived site speed. Be sure to check out Google PageSpeed Insights to see if your site is passing the Optimize CSS Delivery rule, and http://www.webpagetest.org/ to see a film strip of how your site loads.