Puntuado con 5 de 5 estrellas

An essential add-on. To fix what Firefox 25 broke create userstyle with the Stylish add-on containing the following:

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
.sidebar-placesTree treechildren::-moz-tree-row,
.placesTree treechildren::-moz-tree-row {
height: 1.3em !important;
border-width: 1px !important;
}


Source: http://www.ghacks.net/2013/11/05/firefox-reduce-line-height-list-elements-browser/

Esta valoración es de una versión anterior del complemento (0.7.20.1-signed).