Firefox userChrome.css for showing close button on tabs on hover and left hand side

userChrome.css

//@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
//@-moz-document url(chrome://browser/content/browser.xul){

	#TabsToolbar #tabbrowser-tabs .tabbrowser-tab:not([pinned]) .tab-close-button {
	  -moz-box-ordinal-group: 0 !important;
	  -moz-margin-start:-4px !important;
	  -moz-margin-end:4px !important;
	}
    
    .tabbrowser-tab:not(:hover) .tab-close-button{ display:none; }
    .tabbrowser-tab:not([pinned]):hover .tab-close-button{ display:block !important; }

    //}