Why root-relative paths break in an app
On a web server, /css/style.css means "from the top of this site". Inside an APK built from HTML, your site lives at https://appassets.androidplatform.net/web/. The top of that origin is outside your files, so /css/style.css is not found and the page renders blank or unstyled. A relative path — css/style.css from the root, ../css/style.css from a sub-folder — works everywhere: on your server, on your disk and in the app.
What gets rewritten
src,href,poster,data-src,actionand every candidate insrcset.- CSS
url(), in<style>blocks, inline styles or a pasted stylesheet. http://localhost:…,127.0.0.1and LAN-IP URLs left over from a dev server.- Full URLs on your own domain, if you enter it.
Protocol-relative (//cdn…) and other external URLs are left alone. Paths built at runtime in JavaScript cannot be seen here; for bundled apps, fix them at the build step — base: './' in Vite, "homepage": "." in Create React App.
Questions people ask
Do I need relative paths for a URL-based app?
No. A URL app loads your live site from its real server, where root-relative paths are fine. Only bundled HTML and ZIP apps need them.
What should a page in a sub-folder use?
Paths that climb out of its folder: from blog/post.html, the stylesheet at css/style.css is ../css/style.css. Enter the file's location and the fixer works it out.