--- title: UI Toolkit: Themes and USS variables | daily.dev description: A walkthrough of building a scalable theme system in Unity's UI Toolkit using USS (Unity Style Sheets) variables. The approach separates structure (UXML) from... canonical: https://daily.dev/posts/ui-toolkit-themes-and-uss-variables-efpmswgar twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: UI Toolkit: Themes and USS variables | daily.dev og:description: A walkthrough of building a scalable theme system in Unity's UI Toolkit using USS (Unity Style Sheets) variables. The approach separates structure (UXML) from... og:url: https://daily.dev/posts/ui-toolkit-themes-and-uss-variables-efpmswgar og:image: https://api.daily.dev/og/posts/EfPmSWgAr.png og:image:alt: UI Toolkit: Themes and USS variables 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. # UI Toolkit: Themes and USS variables **[Unity](https://daily.dev/sources/unity)** · 8 min read · 0 upvotes · 0 comments ## Summary A walkthrough of building a scalable theme system in Unity's UI Toolkit using USS (Unity Style Sheets) variables. The approach separates structure (UXML) from styling, defines reusable USS variables in a shared style sheet, and creates separate light/dark theme style sheets that assign values to those variables. A small C# controller script swaps the active theme style sheet at runtime, causing UI Toolkit to automatically recalculate and update all dependent styles. The guide also covers reading USS variables from C# using the custom style API, and briefly introduces Theme Style Sheets (TSS) for panel-level theming in larger projects. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Hands-On UI Toolkit Tutorials For Unity Devs](https://daily.dev/posts/hands-on-ui-toolkit-tutorials-for-unity-devs-uiybcyb9o) · 80 LEVEL · 0 upvotes · 0 comments - [No-Hassle Visual Studio Code Theming: Building an Extension](https://daily.dev/posts/no-hassle-visual-studio-code-theming-building-an-extension-wyiwzoyp3) · CSS-Tricks · 2 upvotes · 0 comments --- Tags: [#c#](https://daily.dev/tags/c#), [#unity](https://daily.dev/tags/unity) [View this post on daily.dev](https://daily.dev/posts/ui-toolkit-themes-and-uss-variables-efpmswgar) ```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":"UI Toolkit: Themes and USS variables","url":"https://daily.dev/posts/ui-toolkit-themes-and-uss-variables-efpmswgar","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/ui-toolkit-themes-and-uss-variables-efpmswgar"},"datePublished":"2026-06-09T14:12:36.330Z","dateModified":"2026-06-09T14:12:54.086Z","description":"A walkthrough of building a scalable theme system in Unity's UI Toolkit using USS (Unity Style Sheets) variables. 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