Phrase elements similar to <em></em> can not only improve the document structure, but also retain the expected visual style. But <small></small> is not very common in daily applications. The first impression is whether Taobao UED is neglecting this small issue?
Regarding <small></small>, the results of searching online are also fragmentary. Some say it is not recommended to use it, and some do not mention its name in the discarded tag. Fortunately, this is explained in detail in the book "Proficient in HTML Semantics, Standards and Styles".
<small>, like <hr><pre><sup><sub><i><b> and a group of brothers, are defined as representative elements. The W3C term is: for elements that can simply specify font information, without semantics. For example: <b>tags are undoubtedly replaced by <em> or <strong>; but <i>tags are difficult to say what is wrong with using them directly when you want to represent a paragraph of foreign language (convention in foreign language display), because when the user uses <span class=>...</span> to express a paragraph of italics, the space occupies a lot more than the former.
For the more complex <big><small>, the author of the book, Paul Haine, did not give a clear answer. In theory, they are purely representing elements and css should be used instead. But some of the industry's weighted figures (Joe Clark) suggest using them to achieve visual effects weighted by importance. The result of the discussion is: there must be gains and losses, and specific issues must be analyzed in detail.
Back to this code on Taobao, the <small></small> tag is a link to skip navigation: <a class=invisible href=#Content>Skip navigation and toolbar</a>. I think that after thinking about it, Taobao UED adopted the same idea as the <i> tag. Instead of defining a <span class=skipNavigation></span> that occupies a lot of html space, it is better to use <small> directly. More importantly, the function of skipping navigation is for users, to be precise, for disabled users when using a reading browser or without a css style definition. The concise <small></small> may be more in line with the spirit of standardization.
The only question is that the <small> under the css naked run is indeed the following font, which shows its non-important intention. But for blind users, has the user experience changed to <small></small> to <strong></strong> more optimized for reading browsers?