Cross-document View Transitions: the CSS that replaces the router

Auditing a static Astro project to remove the ClientRouter component — it had no JS state to preserve between pages. One CSS rule in the global stylesheet is all it takes:

src/styles/global.css

@view-transition {
  navigation: auto;
}

That's it. The browser intercepts navigation, captures the current document's visual state, loads the next page in background, and runs a native cross-fade. No JavaScript. No router. No extra config. All modern browsers support it natively; Baseline 2026.

Shared element transitions between pages

The real power isn't the global fade — it's morphing specific elements across documents. Give the same view-transition-name to matching elements in both pages, and the browser animates the transition between them automatically:

src/styles/global.css

/* Post listing page */
.post-card img {
  view-transition-name: post-hero;
}

/_Post detail page_/
.hero-image {
view-transition-name: post-hero;
}

The name acts as an anchor between the two documents. The browser finds the pair and builds the animation. Zero JavaScript.

When ClientRouter is still the right call

Pure CSS vs ClientRouter

Pure CSS @view-transition is enough when...

Your site is a static MPA with no shared JS state between pages.
You only need navigation animations (fade, image morph).
You want zero JavaScript in the layout shell.

Use ClientRouter when...

You need to preserve audio/video players across page changes.
You use reactive stores (nanostores, Zustand) that shouldn't reset.
You need programmatic control over when and how the transition starts.

If you were using ClientRouter purely for enter/exit animations, this CSS replaces it at zero cost. The full trade-off breakdown is in the ClientRouter in Astro 6 TIL. If transitions don't show up on mobile, the debugging View Transitions on mobile TIL covers the full diagnostic system.

…g CO₂