feat(theme): improve navbar alignment

[yorunning]

调整navbar对齐方式，确保navbar-center位于页面正中心。

before

after

[Mister-Hope]

Nice catch about the alignment, but I doubt this is a proper solution. Maybe you should try to edit the site title text length to see whether it still align well.

from your edits, you are making the center and right box becomes a horizontal flex one, but I don’t think this means the center is at the center.

So if you do think your fix is valid, please provide a hidden site title screenshots and a pretty lone one. Or you may reorganize the layout through options (e.g. reverse their sorting to see if it works well.)

[yorunning]

please provide a hidden site title screenshots

before:

after:

and a pretty lone one.

before:

after:

Or you may reorganize the layout through options (e.g. reverse their sorting to see if it works well.)

尝试改变navbarLayout布局、删减项目、颠倒顺序显示都正常。但是标题过长（宽度超过页面1/3）并不能正真的居中，属于是极端情况。

before:

after:

[Mister-Hope]

Thanks for the detailed reply. Are the extra div really needed? I think it's possible to move styles into the original container.

So my concern is why is a extra div being added?

BTW this reply is not necessary, I will check it myself before merging if you are too busy to reply this.

[yorunning]

So my concern is why is a extra div being added?

You are right. This is the simplest repair I know.

[Mister-Hope]

Thanks for contribution