Não é possível fechar páginas no Firefox depois de ocultar a barra de guias

Question

No meu style.css (que afeta a aparência do Firefox), escondi a barra de guias usando

    display: none !important;

qual deve ocultar apenas a barra de guias. Mas agora quando eu vou fechar as abas (usando "d" no vimperator) eu recebo este erro:

    TypeError: this.selectedItem is null

que parece ser alguma forma de JS ou jQuery. O Firefox realmente precisa dessa barra de abas? Meu navegador é praticamente inutilizável com o CSS ativado. Se alguém sabe como consertar isso é ótimo

Aqui está o CSS que, acredito, está causando o problema

       /* TABS */
.tabbrowser-tab[fadein]:not([pinned]) { min-width: 100px !important; max-width: /*180px*/ 100% !important; }
tab {
    font-family: var(--tab-fonts) !important;
    height:1px !important; min-height: 1px !important;
    font-size: var(--tab-font-size); text-shadow: none !important; text-align: left /* center | left */ !important;
}

.tabbrowser-tab label { padding: 0 22px 0 22px !important; display: none !important;  }

#tabbrowser-tabs .tabbrowser-tab[pinned]            { width: 1px !important; }
#tabbrowser-tabs .tabbrowser-tab[pinned] label      { display: none !important; }

#tabbrowser-tabs .tabbrowser-tab .tab-icon-image {
    margin: 0 -10px 0 16px !important;
    width: var(--tab-icon-size) !important;
    height: 1px !important;
}

.tab-icon-image {
    display: none !important;
}

.tabbrowser-tab *, .tabs-newtab-button * {
    background: #7E9C7A!important; list-style-image: none !important;
    margin: 0 0 0 0 !important; padding: 0 0 0 0 !important;
    -moz-appearance: none !important;
}

#tabbrowser-tabs .tabbrowser-tab[pinned] .tab-stack { height: 1px !important; width: 100% !important; }
#tabbrowser-tabs .tabbrowser-arrowscrollbox .box-inherit.scrollbox-innerbox { max-height: 1px !important; }
.scrollbutton-up, .scrollbutton-down { border: none !important; }

#tabbrowser-tabs[overflow]:not([positionpinnedtabs]) { -moz-padding-start: 20px !important; }

.tabbrowser-tab[selected="true"] .tab-stack {
            background-color: #FFFFFF!important;
    border-radius: 0px !important; position: relative !important;
    /*border-top: 1px solid #dc52a5 !important;/**/
}
.tabbrowser-tab[selected="true"]:before { /* Left Triangle (of selected tab) */
    content: '' !important; display: var(--tab-triangle);
    position: absolute !important; top: 0 !important; left: var(--tab-overlap) !important;
    width: 0 !important; height: 0 !important;
    border: none !important; z-index: 2 !important;

    /*border-left: calc(var(--tab-height)/2) solid var(--bg-dark) !important;
    border-top: calc((var(--tab-height)/2) - var(--tab-triangle-correction)) solid var(--bg-light) !important;
    border-bottom: calc((var(--tab-height)/2) + var(--tab-triangle-correction)) solid var(--bg-light) !important;/**/
    /**/border-top: var(--tab-height) solid  #7E9C7A !important;
    border-right: calc(var(--tab-height)/2) solid  #7E9C7A !important;/**/
}
.tabbrowser-tab[selected="true"]:after { /* Right Triangle (of selected tab) */
    content: '' !important; display: var(--tab-triangle);
    position: absolute !important; top: 0 !important; right: var(--tab-overlap) !important;
    width: 0 !important; height: 0 !important;
    border: none !important; z-index: 0 !important;

    /*border-right: calc(var(--tab-height)/2) solid var(--bg-dark) !important;
    border-top: calc((var(--tab-height)/2) - var(--tab-triangle-correction)) solid var(--bg-light) !important;
    border-bottom: calc((var(--tab-height)/2) + var(--tab-triangle-correction)) solid var(--bg-light) !important;/**/
    /**/border-top: var(--tab-height) solid #7E9C7A !important;
    border-left: calc(var(--tab-height)/2) solid #7E9C7A !important;/**/
}



#TabsToolbar, #tabbrowser-tabs {
    -moz-appearance: none !important;
    height: 1px !important; width: 0px !important;
    margin: 0 var(--tab-strip-margin) !important;
    background-color: #7E9C7A!important;
    display: none !important;

    /* --- Uncomment the line below to attach the url-bar to the tab-bar [EXPERIMENTAL] (Require a line in "#nav-bar" above) --- */
    /*margin-left: 150px !important;/**/
}
#TabsToolbar::after { display: none !important; }
.tabbrowser-tab::before, .tabbrowser-tab::after { background: none !important; }