How to Customize Your Book’s CSS

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At, we have more than 50 different book designs to choose from. Still, sometimes our users want to adjust the design of a book theme to make it unique to them or to fine-tune one aspect of a layout to serve the needs of a particular book. Pressbooks supports that! Generally you can customize most elements of your theme in your book’s CSS. If you don’t know CSS, that process might seem intimidating, but we’re going to do our best to make it easier here.

What is CSS?

To understand CSS, you first need to understand the concept of “styles” for graphic and Web design.

Smart designers have long used what’s known as “style sheets” to design books, Web sites and more.

A style sheet is a master reference that tells a software to render all elements of the same kind in the same style–to make all second-level headers bold, for instance, or to make all paragraph text a certain font.

The benefit to styling a document this way rather than styling each element individually is the ability to make universal changes throughout your document. So instead of making the same change thousands of times, you only have to make it once. This means not only can you avoid that laborious process of styling each element individually, you won’t have to undo that design line by line if you ever want to change it.

How to Get Into Your CSS in Pressbooks

Pressbooks allows you to customize your CSS to get a design unique to you. It also lets you customize CSS differently for your different outputs: Web book, ebook and PDF (print) book.

To customize your CSS, you must first apply the “Custom CSS” theme. To do this, go to Appearance / Themes / Custom CSS and click Activate.

Custom CSS theme in Pressbooks

Before you can customize your CSS, you’ll need to choose and activate the Custom CSS theme.

Next, click on Edit CSS on the left dashboard. (Important Note: This option will not appear until you’ve activated the Custom CSS theme.)

Don’t worry. You don’t have to start from scratch–you can tell the Custom CSS  to “inherit” the styles of a pre-built theme.

CSS screen Pressbooks

You can create different CSS stylings for each of your book’s outputs.

Specify the theme you’d like to start with for the Web, ebook and PDF versions of your book.

If this isn’t clear yet, this video may help walk you through it.

How to Customize Your Book’s CSS

If there’s something you want to adapt in Pressbooks, chances are you can do so in the CSS.

Here are just a few examples of elements you can modify using CSS:

  • font family
  • font color and size
  • paragraph spacing
  • text alignment
  • what length of word is considered a widow or orphan

This chapter on CSS in our User Guide gives more information on how to customize these elements using CSS.

Where to Learn CSS

You may want more help learning CSS to get the specific adjustments you need.

We don’t give lessons in CSS, but there are many places that do. A few we recommend are Codeacademy (free) and (not free).

Finding Someone to Help With CSS is a self-service platform, but there are many professionals who will lay out your book for you using Pressbooks if it’s more than you want to take on.

Handsome Formatting and Interbridge are two such book-design companies we recommend.


Aug. 28, 2018 Update: We’ve changed the way you can access and edit your CSS in Pressbooks. Current step-by-step instructions are now located in this User Guide chapter