This test has
<meta name="viewport" content="width = 380"> tag.
This is a paragraph that is supposed to take the entire width (whatever that may be) of the browser canvas and even wrap to the next line. Obviously, since no width has been defined on anything, the browser must have some clever way of handling this paragraph, or it’ll be unreadable. Right now I feel that the different between browser experiences will mainly depend on handling this issue. And this span is supposed to span 50% of the paragraph.