WITChromeMenu style class has 13 sub classes, controlling the global appearance of the Drop Down menu, but also its behavior : change with caution.

Example (this document styles : extract of style sheet. Do not change values shown in red) :

/* WIT wrapping of Chrome CSS Drop Down Menu (courtesy of www.dynamicdrive.com)          */
.WITChromeMenu { 
/* Insert properties */
float:right;
}

/* Chrome CSS Drop Down menu bar          */
.chromestyle  { 
width: 100%;
font-weight: 100;
font-family:arial;
font-size:100%:
}

/* Chrome CSS Drop Down Menu          */
.chromestyle:after { 
/*Add margin between menu and rest of content in Firefox*/
content: ".";
display: block;
height: 0;
clear: both;
visibility: hidden;
}

/* Chrome CSS Drop Down menu : horizontal bar          */
.chromestyle ul { 
border: 1px solid #BBB;
width: 100%;
background: url(../extra/chromebg.gif) center center repeat-x; /*THEME CHANGE HERE*/
padding: 4px 0;
margin: 0;
font-size:100%;
text-align: left; /*set value to "left", "center", or "right"*/
}

/* Chrome CSS Drop Down Menu : horizontal bar elements list          */
.chromestyle ul li { 
display: inline;
}

/* Chrome CSS Drop Down Menu : horizontal bar links          */
.chromestyle ul li a { 
color: #494949;
padding: 4px 7px;
margin: 0;
text-decoration: none;
border-right: 1px solid #DADADA;
}

/* Chrome CSS Drop Down Menu : horizontal bar links, hovered          */
.chromestyle ul li a:hover { 
text-decoration: none;
background: url(../extra/chromebg-over.gif) -8px center repeat-x; /*THEME CHANGE HERE*/
}

/* Chrome CSS Drop Down Menu : horizontal bar links, visited          */
.chromestyle ul li a:visited { 
color: #494949;
}

/* Chrome CSS Drop Down Menu : trick...          */
.chromestyle ul li a[rel]:after { 
/*HTML to indicate drop down link*/
/*content: " v";
content: " " url(../extra/downimage.gif); /*uncomment this line to use an image instead*/
}

/* Chrome CSS Drop Down Menu : Dropdown pane          */
.dropmenudiv { 
border: 1px solid #BBB; /*THEME CHANGE HERE*/
border-bottom-width: 0;
font-size:90%;
line-height:18px;
text-align:left;
background-color: white;
color:grey;
width: 160px;
/* Do not change below */
position:absolute;
top: 0;z-index:100;
visibility: hidden;
filter: progid:DXImageTransform.Microsoft.Shadow(color=#CACACA,direction=135,strength=4); /*Add Shadow in IE. Remove if desired*/
}

/* Chrome CSS Drop Down Menu : dropdown pane links          */
.dropmenudiv a { 
width: auto;
display: block;
text-indent: 3px;
border-bottom: 1px solid #BBB; /*THEME CHANGE HERE*/
padding: 2px 2px;
text-decoration: none;
font-weight: 100;
color: #666666;
}

/* Chrome CSS Drop Down Menu : IE only hack          */
* html .dropmenudiv a { 
width: 100%;
}

/* Chrome CSS Drop Down Menu : dropdown link, hovered          */
.dropmenudiv a:hover { 
background-color: #F0F0F0;
text-decoration: none;
}

/* Chrome CSS Drop Down Menu : dropdown link, visited          */
.dropmenudiv a:visited { 
color: #666666;
}