tree-stype-tabs css fix

userChrome.css

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

/*
 * 1) open `about:support`, and open profile folder
 * 2) create folder `chrome`
 * 3) place this file inside using the filename `userChrome.css`
 */

#TabsToolbar {
	visibility: collapse !important;
}

#sidebar-header {
	display: none;
}