Pushed to git - this is actually just a big hack, so it'll only count curly bracket depth.
Example:
#main .ace-tm .ace_curly.ace_paren.ace_depth0 {
color: #FF79C6;
}
#main .ace-tm .ace_curly.ace_paren.ace_depth1 {
color: #C6FF79;
}
#main .ace-tm .ace_curly.ace_paren.ace_depth2 {
color: #79C6FF;
}