@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

#search-container #searchbar
{
max-width: 150px !important;
min-width: 150px !important;
-moz-margin-end: -80px !important;
}
#search-container #searchbar:hover
{
max-width: 300px !important;
min-width: 300px !important;
-moz-margin-end: -45px !important;
}