Bring comments into a scrollable section

Some articles, like the old "var," may not be very attractive to read. We just know that 'var' should not be used, rather than reading a lot about it. However, one may intend to read it, especially when an interview is coming up.

Jumping into the article for the first time can feel overwhelming; it appears to be a long read because of the lengthy scrollbar.


But actually it ends half way and the rest half of it are just comments.


The feature request is to place the comments in a scrollable section so that the page's scrollbar accurately reflects the length of the article.

首先检查文章页面布局和评论渲染，然后复现旧版 "var" 文章中的长滚动条。完成的标准是：评论占据独立的可滚动区域，并且页面滚动条反映文章内容，而不是完整的评论列表。

由索引模型根据 Issue 内容生成。