The standard login is really standard.

It's great for standard ERP systems, but custom ERP systems need a custom view:

To change the login view, simply use an external css file and set following styles:

.jvx #glasspane-login,
.jvx_valo #glasspane-login 
{
    background-image: url("images/login_background.jpg");
    background-size: cover;
}
 
.jvx .loginwindow .v-window-contents,
.jvx_valo .loginwindow .v-window-contents
{
    background: transparent;
}
 
.jvx .loginwindow,
.jvx_valo .loginwindow
{
    opacity: 0.75;
    background: #efefef;
}