20 November, 2014 When to use @extend; when to use a mixin Written by Harry Roberts on CSS Wizardry. Table of Contents When to use @extend When to use a mixin tl;dr tl;dr;tl;dr This is a question I get asked a lot by my clients: When should we use a mixin, and when should we use @extend? There’s an old rule of thumb which states that mixins without arguments are bad—that mixins which just duplicat