Inlines external CSS into HTML elements.
inlinestyler is an easy way to locally inline CSS into an HTML email message.
Styling HTML email is a black art. CSS works, but only when it’s been placed inline on the individual elements (and event then, not always) - which makes development frustrating, and iteration slow.
The general solution is to use an inlining service, which takes a message with the CSS placed externally, and rewrites it so that all CSS is applied to the individual elements. The most widely used of these services - and as far as I can tell, the one that powers CampaignMonitor - is Premailer. It’s a great service, and the guys behind it put a lot of work into keeping it up to date with the most recent discoveries in what works and what doesn’t.
inlinestyler takes (most) of the functionality of Premailer, and makes it available locally, accessible without having call a remote service.
To see what inline-styler can do, check out this demo.
Dave Cranwell wrote the original inline-styler single-app Django project, and (graciously) released it. inlinestyler is a refactor of that project into a free-standing package usable outside of Django.
inlinestyler requires the following packages in order to run:
- cssutils (which will be installed by pip)
- lxml (which we assume you already have installed through your OS)
It also requires a css_complaiance.csv file, which indicates the compatibility of various email clients with certain CSS features. This is included with the package, but can be updated manually from Campaign Monitor’s spreadsheet.
from inlinestyler.utils import inline_css message_inline_css = inline_css(message_external_css)
message_external_css must be a string containing the message to be inlined, with the CSS presented in the HTML as one of:
- an absolute link <link rel="stylesheet" href="http://mysite.com/styles.css" />
- a <style> block in the <head>, without the use of @import.
The code will also calculate an estimate for how compatible your message is with various clients (using the css_compliance.csv file), but this number isn’t yet exposed.
All development happens at github: http://github.com/dlanger/inlinestyler.
Contributions are always more than welcome. If you see something missing, add it in and send me a pull request.
This distribution is licensed under the New BSD License. Please see the LICENSE file for a full copy of the license text.
As far as I can tell, Dave Cranwell released the underlying inline-styler project into the public domain:
I’m […] releasing it to the public after many requests for the source.