navbar menu may exceeds the screen

[likui628]

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

If there are many navbar menus or the users have a low-resolution screen,
it is supposed that the navbar menus may succeed the screen height.

Describe the solution you'd like

add max-height and overflow-y properties
https://github.com/vuejs/vitepress/blob/main/src/client/theme-default/components/VPMenu.vue

.VPMenu {
  /** +++ **/
  max-height: 90vh;
  overflow-y: scroll;
 / ** +++ **/
  border-radius: 12px;
  padding: 12px;
  min-width: 128px;
  border: 1px solid var(--vp-c-divider-light);
  background-color: var(--vp-c-bg);
  box-shadow: var(--vp-shadow-3);
  transition: background-color 0.5s;
}

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.

[brc-dd]

Just realized that this is on Vue docs too. Patched it to look like this:

The max-height thing will work better with calc(100vh - var(--vp-nav-height-desktop)) (also it needs to be added only for desktops min-width: 768px). On mobiles it still works fine. Feel free to create a PR or I'll make once I get some time.