--- title: m4 Macros and CSS | daily.dev description: A practical guide to using the m4 macro processor to manage CSS constants like theme colors, avoiding repetitive hard-coded values. Covers defining macros, the... canonical: https://daily.dev/posts/m4-macros-and-css-cevtfybjw twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: m4 Macros and CSS | daily.dev og:description: A practical guide to using the m4 macro processor to manage CSS constants like theme colors, avoiding repetitive hard-coded values. Covers defining macros, the... og:url: https://daily.dev/posts/m4-macros-and-css-cevtfybjw og:image: https://api.daily.dev/og/posts/cevtFyBJW.png og:image:alt: m4 Macros and CSS og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # m4 Macros and CSS **[Beej's Blog](https://daily.dev/sources/beej)** · 7 min read · 0 upvotes · 0 comments ## Summary A practical guide to using the m4 macro processor to manage CSS constants like theme colors, avoiding repetitive hard-coded values. Covers defining macros, the dnl directive, including external files, doing integer math with eval(), and applying m4 to HTML. Acknowledges modern alternatives like Less and Sass but highlights m4's advantages: lightweight, POSIX-standard, minimal dependencies, and easy to run. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Repeating Ourselves Less with M4](https://daily.dev/posts/repeating-ourselves-less-with-m4-meax6hzos) · Lobsters · 0 upvotes · 0 comments - [A pragmatic guide to modern CSS colours - part one](https://daily.dev/posts/a-pragmatic-guide-to-modern-css-colours---part-one-wffwwe3kn) · Piccalilli · 1 upvotes · 0 comments --- Tags: [#css](https://daily.dev/tags/css) [View this post on daily.dev](https://daily.dev/posts/m4-macros-and-css-cevtfybjw) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"m4 Macros and CSS","url":"https://daily.dev/posts/m4-macros-and-css-cevtfybjw","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/m4-macros-and-css-cevtfybjw"},"datePublished":"2026-03-31T12:28:09.507Z","dateModified":"2026-03-31T12:39:05.306Z","description":"A practical guide to using the m4 macro processor to manage CSS constants like theme colors, avoiding repetitive hard-coded values. Covers defining macros, the...","image":"https://media.daily.dev/image/upload/s--OHB84bZF--/f_auto/v1722860399/public/Placeholder%2010","thumbnailUrl":"https://media.daily.dev/image/upload/s--OHB84bZF--/f_auto/v1722860399/public/Placeholder%2010","isAccessibleForFree":true,"articleSection":"Beej's Blog","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Beej's Blog","logo":"https://media.daily.dev/image/upload/logos/placeholder.jpg","url":"https://daily.dev/sources/beej"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/m4-macros-and-css-cevtfybjw","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"css","timeRequired":"PT7M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Beej's Blog","item":"https://daily.dev/sources/beej"},{"@type":"ListItem","position":3,"name":"m4 Macros and CSS"}]} ```