Client-side less.js vs. Server-side compilation for dynamic theming

Styling Strategy for Runtime Flexibility

A project requires a mechanism to allow users to modify theme variables (such as primary colors) dynamically without requiring a full application rebuild or deployment. The current architecture evaluates two documented Less CSS processing methods.

Client-side compilation via less.js allows for runtime variable manipulation directly in the browser. However, this introduces a dependency on a JavaScript runtime for styles and may lead to a Flash of Unstyled Content (FOUC) during the initial page load.

Server-side compilation ensures faster initial rendering and removes the client-side runtime dependency by producing static .css files during the build process. This approach optimizes performance but eliminates the ability to change Less variables via JavaScript at runtime.

• Constraint: Need for live theme switching.
• Constraint: Requirement for minimized initial render latency.

Which approach is more sustainable for a production environment requiring both performance and dynamic styling? Are there documented methods to achieve runtime variable updates while utilizing server-side compiled CSS?