Firefox userChrome.css

/* Place the sidebar on the right edge of the window  */
window > hbox {
   direction:rtl;
}
window > hbox > * {
   direction:ltr;
}

/* Make the Search box flex wider */ 
#search-container { 
   -moz-box-flex: 200 !important; 
}
#searchbar {
   -moz-box-flex: 200 !important;
}

/* Tabs Close Box None  */
.tabbrowser-tabs > stack {display: none;}

/* Change appearance of tabs */
tab{
   -moz-appearance: none !important;
   text-align: center !important;
   padding-top:1px !important;
   padding-bottom:0px !important;
   margin:0 !important;
   font-weight:normal !important;
}
/* Change appearance of inactive tabs */
tab:not([selected="true"]) {
   background-color: darkgray !important;
   color: dimgray !important;
}