Fix:
```sh
$ yarn run vite build -c vite.sdk-assets-config.js
yarn run v1.22.18
$ C:\Users\MLM\Documents\GitHub\element\hydrogen-web\node_modules\.bin\vite build -c vite.sdk-assets-config.js
locally linked postcss
cleanUrl(id) C:/Users/MLM/Documents/GitHub/element/hydrogen-web/src/platform/web/ui/css/themes/element/theme.css C:/Users/MLM/Documents/GitHub/element/hydrogen-web/src/platform/web/ui/css/themes/element/theme.css?type=runtime
[build-themes] Could not load C:/Users/MLM/Documents/GitHub/element/hydrogen-web/src/platform/web/ui/css/themes/element/theme.css?variant=light: ENOENT: no such file or directory, open 'C:\Users\MLM\Documents\GitHub\element\C:\Users\MLM\Documents\GitHub\element\hydrogen-web\src\platform\web\ui\css\themes\element\theme.css'
error during build:
Error: Could not load C:/Users/MLM/Documents/GitHub/element/hydrogen-web/src/platform/web/ui/css/themes/element/theme.css?variant=light: ENOENT: no such file or directory, open 'C:\Users\MLM\Documents\GitHub\element\C:\Users\MLM\Documents\GitHub\element\hydrogen-web\src\platform\web\ui\css\themes\element\theme.css'
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
```
Regressed in:
https://github.com/vector-im/hydrogen-web/pull/769/files#diff-5432b565e86d2514c825ed9972c37ea19820bf12b5d8d3203fc9d4ea4654bd34L20 where the `const path = require('path');` was removed but we also started using `path` in more places which needed the same treatment.
When making the fix, we also have to make sure we don't also regress:
https://github.com/vector-im/hydrogen-web/pull/750
