Windows Phone 8.1 supports transparent start screen tiles, and apps can make use of the backgroundColor=transparent setting in their manifest.
However, for Pinned sites either the <meta> tag in the HTML markup, or the browserconfig.xml should be used, containing the <TileColor> element. Is it possible to specify that the tile should be left transparent in this case? I tried using the value transparent or removing the element, but this results in the tile having black background.