How can I separate 2 sidebar blocks from each other using a separator (space)?

[vexxy]

my additional.css style for this is:

#sidebar_container .underblock {background: transparent; height: 20px;}
#sidebar_container > ul {
    -moz-border-radius:0px;
    -webkit-border-radius:: 0px;
    -moz-box-shadow: none;
    background:transparent;
    border:0;
}
#sidebar_container .block {
    background-color:{vb:stylevar forum_sidebar_background.backgroundColor};
    border:{vb:stylevar forum_sidebar_border};
    -moz-border-radius:{vb:stylevar border_radius}; /* border_radius */
    -webkit-border-radius: {vb:stylevar border_radius}; /* border_radius */
    -moz-box-shadow:-2px 2px 2px {vb:stylevar shadow_color}; 
}

but there are no visible changes, looks the same :/