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

/* HIDE FAVICON/CLOSE BUTTON WHEN NOT HOVERED */
.tabbrowser-tab:not(:hover) > .tab-close-button,
.tabbrowser-tab:not(:hover) > .tab-icon-image,
.tabbrowser-tab[first-tab="true"][last-tab="true"] > .tab-icon-image {
opacity: 0.0 !important;
}
/* SHOW CLOSE BUTTON ON HOVER AND THROBBER IF BUSY */
.tabbrowser-tab:hover > .tab-close-button,
.tabbrowser-tab[busy] > .tab-icon-image,
.tabbrowser-tab[first-tab="true"][last-tab="true"][busy] > .tab-icon-image {
opacity: 1.0 !important;
}

/* TAB TITLE MARGINS */
.tabbrowser-tab .tab-text,
.tabbrowser-tab[first-tab="true"][last-tab="true"]:hover > .tab-text {
margin-left: -12px !important;
margin-right: -12px !important;
}

/* TAB TITLE MARGINS ON HOVER (OR IF BUSY) */
.tabbrowser-tab:hover > .tab-text,
.tabbrowser-tab[busy] > .tab-text,
.tabbrowser-tab[first-tab="true"][last-tab="true"][busy] > .tab-text,
.tabbrowser-tab[first-tab="true"][last-tab="true"][busy]:hover > .tab-text {
margin-left: 5px !important;
margin-right: 5px !important;
}