Message box button styles in "classic" themes

Steps to Reproduce

run messagebox.zul using breeze/sapphire/silvertail

Actual Result

Breeze: not centered, no spacing between buttons

Sapphire/Silvertail: no spacing between buttons

Expected Result

centered and some spacing

Debug Info

Root Cause

missing css styles in zk.wcs

Workaround

.z-messagebox-buttons {
	text-align: center;
}
.z-messagebox-buttons>* {
	margin: 0 2px;
}