fix(pc): close #62, get scrollBarWidth and paddingRight first

[BuptStEve]

Summary

add demos and fix #62

What kind of change does this PR introduce? (check at least one)

• [x] Bug fix
• [x] Docs

The PR fulfills these requirements:

• [x] When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

You have tested in the following platforms:

• [x] PC
• [x] iOS
• [x] Android