The following ZK Code shows how to change all the border color of the window
<zk>
<style>
.z-window-modal-hm, .z-window-modal-br,
.z-window-modal-cr, .z-window-modal-cl,
.z-window-modal-hr, .z-window-modal-tr,
.z-window-modal-hl { background-image:none; background-color
: #0C6BA8; }
.z-window-modal-icon { width: 20px; height: 16px;
border-width: 1px; border-style: solid; border-color: #0C6BA8
#0C6BA8 #0C6BA8 #0C6BA8; box-shadow: inset 0 1px 0 #0C6BA8,
inset -1px -1px 0 #0C6BA8, inset -1px -2px 0 #0C6BA8; }
.z-window-modal-close { background:url('../images/close.jpg')
transparent no-repeat 0 0; }
.z-window-modal-header, .z-window-modal-header-noborder {
padding-top : 1px; padding-right : -1px; padding-bottom : 1px;
padding-left : 0; margin-right: -4px; }
</style>
<window id="win" title=" " width="520px" height="490px"
border="normal" minimizable="false" mode="modal" maximizable="false"
closable="true" action="show: slideDown;hide: slideUp">
</window>
</zk>