The winter bash "snowflake" icon in the top nav is missing when the "full site" is rendered on my iPhone 5 using both chrome and safari. All Stack Exchange sites affected.
I'm looking at the same page simultaneously on desktop and mobile and the desktop has a little "2" in a light blue square to the left of the stack exchange drop down, but my mobile shows nothing there.
Having clicked the little "2" on desktop, the snowflake then appears instead. Still nothing on mobile.
A possible cause is that on the desktop, there are a couple of inches of space to the left of the drop down, but on mobile it is almost hard against the left edge - there may be more room for it to render there.