presentation, manner, personal expression
Style, in a general sense, can be defined in contrast to content: content refers to what is being said, while style refers to the way we are saying it. This distinction is easily seen, for example, in representational painting: there's more than one way to paint a tree. In music, however, there is no tree; music is by nature abstract, and a change in style is a change in content.
The meaning of style in music is very ambigous. It can broadly refer to genre, as in "jazz" or "classical," or to sub-genres like "Dixieland" and "doo-wop"; it can refer to a composer, as in "the style of Joni Mitchell, " or to a period, as in "Baroque." Musical styles can be defined by a general way of playing, such as "stride piano," or by the way an individual plays, as in "the style of Bill Evans"; they can be defined by a rhythm, such as "bossa nova," or by a purpose, such as "dance music."
Ambiguities aside, we can generally say that style refers to the manner in which something is presented. In a casting, the Style Card refers to presentation, to the way we portray ourselves or what's at hand. As style in music frequently refers to individual proclivities, the Style Card can also indicate expressing ourselves in an individual way.
To divine the meaning of this card in a casting, consider the Solfege Die it was drawn above or under.
Click here to learn more about the Compositional Cards as a whole.