Anton Bobylev

Pug’s template inheritance is a powerful feature that allows you to split complex page template structures into smaller, simpler files. However, if you chain many, many templates together, you can make things a lot more complicated for yourself.

Note that only named blocks and mixin definitions can appear at the top (unindented) level of a child template. This is important! Parent templates define a page’s overall structure, and child templates can only append, prepend, or replace specific blocks of markup and logic. If a child template tried to add content outside of a block, Pug would have no way of knowing where to put it in the final page.

GOOD:

extends ./layout.pug

block content
  div some content

BAD:

extends ./layout.pug

block content
div this content isn't inside a block