https://stackoverflow.com/questions/54627038/will-whitespace-or-wrap-be-ignored-between-two-block-elements-in-html
块级和行级元素的空格合并问题https://developer.mozilla.org/en-US/docs/Web/CSS/white-space
可折叠字符 https://msdn.microsoft.com/en-us/library/dn918341.aspx
字符编码 https://www.fileformat.info/info/unicode/char/000d/index.htm
UseAge: [03]