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Blitz eBook Framework

An eBook framework (CSS + template) which mantra is “finding simple solutions to complex issues.”


Blitz is released under MIT Licence © 2016, Jiminy Panoz.


You can either add blitz.css (and blitz-kindle.css) in your EPUB file or an alternative stylesheet.

blitz.css is commented but you’ll find an uncommented version in the AltStylesheets folder (which helps you save some 7kb).

In this folder, you’ll also find blitz-lite.css and blitz-reset.css (normal + minified).

  1. blitz-lite.css should be enough for simple books like novels and essays (it’s 3kb);
  2. blitz-reset.css is just… the reset we’ve designed (it’s 1kb).

Add styles on top of those two is up to you… But you’ll then miss the powerful tools we’ve built in LESS!

Compile LESS

Either use the GUI or, if you’re one of the old-school type…

For core

lessc blitz.less blitz.css

For Kindle

Either uncomment @import 'blitz-kindle'; in blitz.less or, if you want to compile a specific kindle stylesheet:

lessc blitz-kindle.less blitz-kindle.css

For Media Queries

You shouldn’t output them in blitz.css as legacy RMSDK (ePub 2) will ignore the entire stylesheet if there are media queries in it—excepted amzn queries.

lessc blitz-mq.less blitz-mq.css

Design & Goals

Blitz was designed to deal with the significant obstacles a newcomer or even an experienced producer might encounter. Its major goals are:

  1. to be simple and robust enough;
  2. to offer a sensible default;
  3. to manage backwards compatibility (ePub 2.0.1 + mobi 7);
  4. to provide useful tools (LESS);
  5. to get around reading modes (night, sepia, etc.);
  6. to not disable user settings.

We have chosen a functional approach (FCSS) but LESS presets are planned to provide meaningful class names depending on eBook’s type (poetry, plays, etc.).

The 4 principles of blitz

  1. Espouse inheritance and the cascade, the 2 fundamental principles of CSS. eBooks are documents, CSS was designed for documents… It’s a match!
  2. Build and refine, don’t style and undo. Don’t override your own styles, create reusable components—the reset should help you do that.
  3. Don’t fight, skirt. Be smart, it’s not worth fighting RS’ default stylesheets (their selectors and !importants are too much hassle), trompe le monde.
  4. Have fun! We’ve done our utmost to help you avoid common pitfalls. You don’t have to deal with the crappiest parts of eBook CSS authoring, sit back and relax.

Useful details

Blitz is leveraging the concept of inheritance. Values inherit and currentColor are being used extensively to make the framework compatible with Reading Systems’ default stylesheets, reading modes (color) and user settings (font-size, font-family, line-height, etc.).

Defaults and a reset do the heavy lifting so it’s just about building on top of this base. Please note Blitz is taking care of defaults RS aren’t necessarily (HTML5 block elements, hyphens and pagebreaks for selected elements, etc.).

Finally, although we try to rely on RS’ typefaces, typography has been fine tuned.

  • The default scale has been chosen to handle various situations well enough (screen/container size, user increasing font-size, typeface used, etc.)
  • Vertical rhythm (line-height + margin and padding) is automatically computed in LESS to enforce consistency. By taking care of vertical rhythm, we’re also achieving horizontal harmony when the eBook is rendered on a (fake) spread: “everything text” lines up on the same baseline grid, which makes for a more comfortable reading experience.
  • sup and sub styling is improved to prevent them from affecting line-height.
  • The whole §8. Breaking Within Words is implemented in LESS.

To sum up, we’ve tried to find a balance and feel like Blitz defaults can help producers get around a lot of possible issues: we don’t need hacks, we don’t have to change values in specific situations using complex media queries.

Related EPUB 3.1 issues

  • The EPUB 3.1 spec should address common reader styling scenarios #671
  • Defining a minimal default stylesheet in the epub spec #672
  • Media Queries #685
  • Possible spec language for reading system CSS handling #693

To do

  • Create Web Page
  • Improve docs
  • LESS Presets
  • Web App
  • Test suite (in the form of EPUB + Kindle files)
  • Init JS Framework (I’m not kidding)
  • Blitz a11y (i.e. implement debug mode for accessibility as a plugin)


  • Readium
  • iBooks
  • Kobo
  • Kindle (mobi7 + KF8)
  • Google Play Books
  • RMSDK (a.k.a. eBooks’ IE 6)



  • Fixed hyphenation (limit chars)


  • added reset styles for hidden attribute to improve backwards compatibility;
  • added a utility for list-style-type: none;
  • an experimental plugin for progressive enhancements is now available (check docs).


  • Added plugin for progressive enhancements.


  • improved hr.transition (won’t screw up vertical rhythm because margins any longer);
  • -webkit-locale now an override (issue #9).

0.95 (Pre-release) -> 1.0 (stable)

  • refacto making the framework much easier to handle and customize (typo is now barebones)
  • asterism is now an SVG background (beware! it’s an external dependency)
  • CSS has been fine-tuned (e.g. limit-lines, tabular numerals, object-fit, etc.)
  • added mixins to override and customize list-style-type
  • prevented blank page at the end of xhtml in reset
  • initialized docs (vanilla docs + API flavored reference)
  • containers’ and images’ classes in vh are now available
  • corrected epub namespace
  • completed utilities (margins, underline, etc.)