//! Nothing is built here. The file exists because `links` in Cargo.toml
//! requires it, and `links` is what makes two copies of this renderer in one
//! dependency graph a resolver error rather than a silent second copy.
//!
//! This crate decides class names. Two versions in one build means the
//! stylesheet a build script generates and the markup the runtime emits can
//! come off different vocabularies and still compile: one build.rs run writing
//! layout.css from one version and tables.css from another.
//!
//! The guard only bites between versions that both declare `links`.