Expected a valid CSS identifier

[sebastiandotdev]

Describe the bug

Hello team,

I try to use nested css in svelte 5 I get an error

Reproduction

https://stackblitz.com/~/github.com/castrogarciajs/todo-list-svelte

Logs

Internal server error: C:/Users/johan/OneDrive/Escritorio/todo-list-svelte/src/routes/+page.svelte:63:0 Expected a valid CSS identifier
  Plugin: vite-plugin-svelte
  File: C:/Users/johan/OneDrive/Escritorio/todo-list-svelte/src/routes/+page.svelte:63:0
  60 |    @media (--OSdark) {
  61 |      background-image: var(--gradient-15);
  62 |    }
     |      ^
  63 |  }
  64 |

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 Intel(R) Core(TM) i5-8300H CPU @ 2.30GHz
    Memory: 895.89 MB / 7.85 GB
  Binaries:
    Node: 20.9.0 - D:\nodejs\node.EXE
    npm: 10.1.0 - D:\nodejs\npm.CMD
    pnpm: 8.11.0 - ~\AppData\Local\pnpm\pnpm.EXE
  Browsers:
    Edge: Spartan (44.19041.3636.0), Chromium (119.0.2151.72)
    Internet Explorer: 11.0.19041.3636
  npmPackages:
    svelte: ^5.0.0-next.14 => 5.0.0-next.14

Severity

annoyance

[Conduitry]

Duplicate of #8587.