Vite's static asset handling from `app.html`

Describe the bug

When loading the fallback page, a blank white page is shown until the JS loads my stylesheet. This is very annoying if I am using a dark background-color, because the page flashes from the blank white page to my dark background color.

Because the stylesheet is imported in my root +layout.svelte, I expect SvelteKit to include it in the head element, but it doesn't.

Related: #1948

Reproduction

https://github.com/GitRowin/svelte-kit-fallback-flash

Logs

No response

System Info

System:
    OS: Windows 10 10.0.22621
    CPU: (12) x64 AMD Ryzen 5 2600X Six-Core Processor
    Memory: 8.46 GB / 15.94 GB
  Binaries:
    Node: 20.0.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 3.5.0 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 9.4.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.22621.1702.0), Chromium (113.0.1774.50)
    Internet Explorer: 11.0.22621.1
  npmPackages:
    @sveltejs/adapter-auto: ^2.1.0 => 2.1.0
    @sveltejs/adapter-static: ^2.0.2 => 2.0.2
    @sveltejs/kit: ^1.18.0 => 1.18.0
    svelte: ^3.59.1 => 3.59.1
    vite: ^4.3.8 => 4.3.8

Severity

annoyance

Additional Information

No response

Start with the linked reproduction and inspect app.html alongside the root +layout.svelte stylesheet import. Reproduce the fallback-page flash and trace when the stylesheet reaches the head. Done means the stylesheet is available before JavaScript loads, avoiding the blank white flash.