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CSS Tricks: running elements

Having the current chapter name and number displayed in each page margin is useful in many situations: quickly turning the pages and checking the current chapter, printing a page and knowing in which part of the book it is, remembering the general topic of a long paragraph when reading a complex essay…

Chapter title and page number in the top margin of the document
The chapter title and page numbre in the page top margin

You can put this information in your documents by defining a named string and using it in your page margins:

@page {
 @top-left { content: string(chapter) }
 @top-right { content: counter(page) }
h2 { string-set: chapter content(text) } 

The string-set property also gives the possibility to include counters in the text that will appear in the margin:

html {
 counter-set: chapter-number;
h2 {
 counter-increment: chapter-number;
 string-set: chapter counter(chapter-number) ". " content(text);
Chapter counter next to the title in the top margin of the document
The chapter counter with its related chapter title in the page margin

Of course, it’s possible to alternate the position of the chapter on left and right pages, and to remove it from some pages using named pages!

Learn more about page margins: