Fix several bugs reported in v7.3

[stevenjoezhang]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines.
• Tests for the changes was maked (for bug fixes / features).
  • Muse | Mist have been tested.
  • Pisces | Gemini have been tested.
• Docs in NexT website have been added / updated (for features).

PR Type

What kind of change does this PR introduce?

• Bugfix.
• Feature.
• Code style update (formatting, local variables).
• Refactoring (no functional changes, no api changes).
• Build related changes.
• CI related changes.
• Documentation content changes.
• Other... Please describe:

What is the current behavior?

Issue resolved: N/A

What is the new behavior?

• Screenshots with this changes: N/A
• Link to demo site with this changes: N/A

How to use?

In NexT _config.yml:

...

Does this PR introduce a breaking change?

• Yes.
• No.

[ivan-nginx]

May I ask why u remove active-menu selector from backend and add it to frontend? Just try to force refresh browser (CTRL+SHIFT+R) and see what happen: in your variant menu will be selected not instantly.

[stevenjoezhang]

It's for PJAX and cache. Because menu items on every page is same, the only difference is the active one. So move the script to the front-end would be better.

Otherwise PJAX have to refresh the whole menu... and the animation (velocity & motion) have to play again... it's too complicated
That's why I decided to use front-end script to highlight the active one

[ivan-nginx]

PJAX don't work with backend?

[stevenjoezhang]

PJAX will load the whole page, and replace the specified elements, e.g. sidebar

[stevenjoezhang]

I did not change the style of RSS or Chat during the reconstruction of the font size. Now Chat looks normal but RSS lacks margin...

5px margin added