# Performance & offline Void ships prefetch-on-hover by default so on-site pages feel instant after the first load. A light-weight service worker (`sw.js`) caches static assets and CDN resources for repeat visits and full offline coverage. ## Asset modes `theme.void.assets.mode` controls how the three lazy-loaded libraries (highlight.js, KaTeX, Mermaid) are referenced at runtime: | Mode | Default | Behaviour | |------|---------|-----------| | `cdn` | **Yes** | Today's runtime CDN loading — deterministic, no build-time network. | | `local` | opt-in | Vendors the libraries into `site//` at build; the built site is fully self-hosted and offline-capable for code blocks and math. | | `bundle` | opt-in | Like `local`, but all three JS bundles are concatenated into a single file (`void-offline.js`). CSS stays per-library because the dual hljs theme toggle cannot be combined. | Every downloaded asset is validated — a failed download logs a warning and the affected component falls back to its CDN URL instead of leaving a broken local reference. ## Inline critical CSS `theme.void.assets.inline_critical_css: true` (requires `mode: local` or `bundle`) inlines the vendored highlight.js theme stylesheets as `