The borders fade from nearly-white ([strike]taken from the background colour of Baghira milk[/strike] taken from my current colourscheme - window backgrounds at 244 grey) at the centre to totally transparent at the edge, with a shadow so that the actual edge of the window is clear.
If anyone wants a version in some colour other than nearly-white, it should be possible to open the border PNGs in the GIMP and change things somehow.
IMHO it looks OK with or without blur on the edges, but I prefer it with (configure in beryl-settings).
I designed this to fit in with Baghira, milk mode (KDE) and Milke (GTK). See Screenshot 2 for GTK and QT apps (Sorry for the poor quality screenshot. Seems that ksnapshot makes poor jpegs compared with GIMP... I might make a proper screenshot later.).
The button pixmaps are lifted straight out of Baghira. The rest is my own work, so this is GPL.
The widget styles shown in the screenshot are Baghira for the Qt apps and and Milke for GTK apps (lower right). I think these are the best styles to use with this to achieve a consistent appearance.
If you vote "Bad", please say why. I'm still improving this.