Reduce layout shifts with classic scrollbars #1054

Is your feature request related to a problem? Please describe.

There's a little different of layout among pages have y-scrollbar or not in wide screen device like desktop.
For example, if I switch pages like https://vitepress.vuejs.org/guide/theme-search.html and pages like https://vitepress.vuejs.org/guide/markdown.html , there will be a little quake , cause some components' width changed.

Describe the solution you'd like

overwrite css rule... but many place to adjust, not only #VPContent

Describe alternatives you've considered

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the docs.
• Read the Contributing Guidelines.
• Check that there isn't already an issue that asks for the same feature to avoid creating a duplicate.