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Critical CSS using Sass and Jekyll
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| $critical-css-only:true !default; | |
| @mixin critical($critical-only:true){ | |
| @if (($critical-css-only and $critical-only) or (not $critical-css-only and not $critical-only)){ | |
| @content; | |
| } | |
| } |
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| @include critical(true){ | |
| // This is critical CSS as it's likely to be above-the-fold | |
| .logo{ | |
| color:red; | |
| } | |
| } | |
| @include critical(false){ | |
| // This is non-critical CSS as it's likely to be below-the-fold | |
| .footer{ | |
| color:blue; | |
| } | |
| } |
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| .logo{ | |
| color:red; | |
| } |
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| @import "critical"; | |
| @import "screen"; |
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| <!doctype html> | |
| <html> | |
| <head> | |
| <title>Demo</title> | |
| <style> | |
| // Critical.css content rendered here using https://github.com/ixti/jekyll-assets | |
| // Alternatively https://github.com/jgallen23/grunt-inline-css could be an option | |
| {% asset critical.css %} | |
| </style> | |
| </head> | |
| <body> | |
| <!-- Non-critical.css before closing body tag --> | |
| <link rel="stylesheet" href="non-critical.css" /> | |
| </body> | |
| </html> |
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| .footer{ | |
| color:blue; | |
| } |
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| $critical-css-only:false; | |
| @import "critical"; |
Is there a way to exclude all but the classes intended for the critical.css file by default? I.e. without wrapping all non-critical styles with critical(false)? This way one only needs to define critical classes for the critical.css file, and the critical styles will be excluded from the non-critical.css file.
You could use breakup for a similar setup too. Plus, you know, media queries.
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This looks pretty useful for components whose position you can guarantee cross-site (footer's an obvious one). I think it might be harder to reap benefits in a component-based workflow: a component might appear below the fold on the home page, but above the fold somewhere else.
I'd guess that the need for critical path is inversely proportional to how large/complex a site is, and the larger and more complex a site is, the less you can guarantee the position of certain components cross-site. But still, this looks pretty cool!