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

@-moz-document url(chrome://browser/content/browser.xul) 
{

  tabbrowser[treestyletab-mode="vertical"] .tabbrowser-tab {
    -moz-border-image: none !important;
    }

  tabbrowser[treestyletab-mode="vertical"] .tab-close-button {
    border: none !important;
    border-width: 0px 0px 0px 0px !important;
    background-image: none !important;
    -moz-border-image: none !important;
    }

  tabbrowser[treestyletab-mode="vertical"] .tab-image-left {
    display: none !important;
    width: 0px !important;
    }
}