我通过Google Developer Tools找到了此代码：
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" class=" js canvas canvastext geolocation crosswindowmessaging websqldatabase no-indexeddb hashchange historymanagement draganddrop websockets rgba hsla multiplebgs backgroundsize borderimage borderradius Boxshadow opacity cssanimations csscolumns cssgradients cssreflections csstransforms no-csstransforms3d csstransitions video audio localstorage sessionstorage webworkers applicationcache svg smil svgclippaths no-opera no-mozilla webkit fontface"> </html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> </html>
显然这些类是用Javascript生成的.
但为什么？为什么这么多的hss根元素的CSS类？
