Mixing of 你 and 您 a stylistic device?
Mixing 您 and 你 is a bad practice. I am not aware of any fashionable usage of the mix, not even in net-speak. Your example is just loosely reviewed.
One rare case where you may see both words in one dialog is when the speaker uses 您 for the listener while uses 你 as a reference to a general 2nd person (similar to &quot;one&quot; in English). In this case 您 and 你 refer to different persons and the mix is not about style. E.g.

“他9点才来。这么重要的事，你怎么能迟到两个钟头呢？您觉得呢？”
&quot;He didn't show up until 9. How could one be late for 2 hours for such an important event?! What do you say?&quot;