Why there is a difference in a "class" attribute value of html tag when viewed in "Page Source" and using "Inspector", I am refering to new Microsoft site?

While inspecting the new Microsoft site source, I observed that the "class" attribute value of the "html" tag when seen in Page Source the value given by Tools/Web Developer/Inspect tool. Value with the tool indicates class="en-in js no-flexbox canvas no-touch backgroundsize cssanimations csstransforms csstransforms3d csstransitions fontface video audio svg inlinesvg" while that is given in Page Source is class="en-us no-js" The question is why different values are shown?