odoo18/addons_extensions/tabbar/static/src/scss/tabbar.scss

.tabbar {
    height: 30px;
    margin-left: 0px;
    width: 100%;
    display: flex;
    .tabbar_left {
        display: flex;
        overflow: hidden;
        flex: 1 1 0%;
        height: 100%;
    }
    .tabbar_right {
        display: flex;
        height: 100%;
        align-items: center;
        justify-content: center;
    }
}