style.css

#zen-tabbox-wrapper {
    padding-top: 36px
}

#TabsToolbar {
    padding: 0px !important;
    margin: 0px !important;
}

#zen-sidebar-icons-wrapper {
    display: none !important;
}

#navigator-toolbox {
    width: 100% !important;
    max-width: 100% !important;
    height: 50px !important;
    position: absolute !important;
    left: 0 !important;
    top: -8px !important;
}

.scrollbox-clip>scrollbox>slot {
    display: flex !important;
    flex-direction: row !important;
    justify-content: flex-start !important;
    flex-wrap: nowrap !important;
    flex: 1 !important;
    overflow-y: scroll;
    scrollbar-width: none;
}

.scrollbox-clip>scrollbox {
    flex: 1 !important;
    display: flex !important;
    ;
}

.scrollbox-clip>scrollbox {
    padding-left: 5px !important;
}

#TabsToolbar-customization-target {
    flex-direction: row !important;
    align-items: flex-start !important;
    flex: 1 !important;
}

#zen-workspaces-button {
    width: 40px !important;
    border-radius: 6px !important;
    margin-top: 5px !important;
    margin-left: 4px !important;
    margin-right: -4px !important;
    height: 27px !important;
}

#alltabs-button {
    display: none !important;
}

.tabbrowser-tab {
    max-width: 180px !important;
    margin: 0px 1px !important;
    min-height: 32px !important;
    height: 32px !important;
    min-width: 64px !important;
    background-color: color-mix(in srgb, var(--zen-primary-color) 15%, black 30%) !important;
    ;
    opacity: 1 !important;
    border-radius: 5px !important;
}

.tabbrowser-tab:hover,
.tabbrowser-tab[selected="true"],
.tabbrowser-tab[multiselected="true"] {
    background-color: color-mix(in srgb, var(--zen-primary-color) 40%, black 30%) !important;
    ;
}

.tabbrowser-tab[pinned="true"] {
    width: 38px !important;
    min-width: 38px !important;
}

#tabs-newtab-button {
    height: 32px !important;
}

#zen-sidebar-splitter {
    display: none !important;
}

#tabbrowser-tabbox {
    padding-left: 6px !important;
}

.menupopup-arrowscrollbox slot {
    display: flex !important;
    flex-direction: column !important;
}

@media (-moz-bool-pref: "zen.view.compact") {
    #navigator-toolbox {
        width: 100% !important;
        max-width: 100% !important;
        height: 50px !important;
        position: absolute !important;
        left: 0 !important;
        top: -4.5px !important;
        padding: 0px 0px !important;

    }

    #navigator-toolbox {
        & #titlebar {
            background: none !important;
            border: none !important;
        }
    }

    #tabbrowser-tabbox {
        padding-left: 0px !important;
    }

    #zen-tabbox-wrapper {
        padding-top: 0px
    }

    @media (-moz-bool-pref: "zen.view.compact.hide-toolbar") {
        html:has(#navigator-toolbox[zen-user-show]) #zen-appcontent-navbar-container {
            top: 44px !important;
        }

        html:has(#navigator-toolbox[zen-user-show]) #zen-tabbox-wrapper {
            padding-top: 38px
        }
    }
}