The reader and login pages use +layout@ breakouts to escape the (root) shell, so anything mounted in (root)/+layout.svelte never reaches them. ModeWatcher was mounted there and duplicated in login/+layout@.svelte, which left the reader's theme toggle inert: it flipped the store but nothing wrote .dark onto <html>. Mount both once at the top-level +layout.svelte instead, which every route inherits regardless of breakouts.
sv
Everything you need to build a Svelte project, powered by sv.
Creating a project
If you're seeing this, you've probably already done this step. Congrats!
# create a new project in the current directory
npx sv create
# create a new project in my-app
npx sv create my-app
Developing
Once you've created a project and installed dependencies with npm install (or pnpm install or yarn), start a development server:
npm run dev
# or start the server and open the app in a new browser tab
npm run dev -- --open
Building
To create a production version of your app:
npm run build
You can preview the production build with npm run preview.
To deploy your app, you may need to install an adapter for your target environment.