PostCSS Import is a plugin for PostCSS that enables the use of @import statements within CSS files. It allows modularizing CSS by merging multiple stylesheets into a single processed output, improving maintainability and compatibility with modern front-end workflows.
The composer-asset-plugin is a Composer extension that allows developers to manage frontend dependencies (like npm and Bower packages) through Composer. This bridges the gap between PHP projects and JavaScript/CSS dependencies.