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template: overrides/main.html
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# Upgrading to 4.x

## Highlights

Material for MkDocs 4 fixes incorrect layout on Chinese systems. The fix
includes a mandatory change of the base font-size from `10px` to `20px` which
means all `rem` values needed to be updated. Within the theme, `px` to `rem` 
calculation is now encapsulated in a new function called `px2rem` which is part
of the SASS code base.

If you use Material for MkDocs with custom CSS that is based on `rem` values,
note that those values must now be divided by 2. Now, `1.0rem` doesn't map to
`10px`, but `20px`. To learn more about the problem and implications, please
refer to [the issue][1] in which the problem was discovered and fixed.

  [1]: https://github.com/squidfunk/mkdocs-material/issues/911

## How to upgrade

### Changes to `mkdocs.yml`

None.

### Changes to `*.html` files

None.
