Dirty workaround of `firefox-gnome-theme` for `Tree Style Tab`

append-this-on-setting-css.css

@media not (prefers-color-scheme: dark) {
    :root[color-scheme="system-color"][data-user-agent*="Linux"] tab-item:not(.active):not(.bundled-active):not(.highlighted), :root[color-scheme="system-color"][data-user-agent*="Linux"] .after-tabs button, :root[color-scheme="system-color"][data-user-agent*="Linux"] .after-tabs [role="button"], :root[color-scheme="system-color"][data-user-agent*="Linux"] #subpanel-selector-anchor, :root[color-scheme="system-color"][data-user-agent*="Linux"] #background {
    --toolbar-non-lwt-bgcolor: welp !important;
    --toolbar-non-lwt-textcolor: welp !important;
  }
  
:root.simulate-svg-context-fill tab-item:not(.collapsed) tab-twisty::before {
  background: var(--in-content-tab-color) !important;
  }

tree-style-tab.css

@media (-moz-bool-pref: "gnomeTheme.extensions.treeStyleTab") {
    :root {
        --delay: 0s;
        --transition-time: 0.2s;
        --positionX1: 0;
        --positionX2: absolute;

        --before-width: 100px;
        --after-width: 200px;
        /* --after-width: 350px; */
    }
    
    #tabbrowser-tabs {
        display: none !important;
    }

    #browser {
        position: relative;
    }
    
    #tabbrowser-tabbox {
        z-index: 0 !important;
    }
    
    #navigator-toolbox {
        z-index: 10 !important;
    }

    #sidebar-box:not([lwt-sidebar]){
        appearance: unset !important;
    }

    #sidebar-box[sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"] {
        min-width: var(--before-width) !important;
        max-width: var(--before-width) !important;
    }

    #sidebar-box[sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
        visibility: collapse;
        display: none;
    }

    #sidebar-box[sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar {
        position: var(--positionX2);
        left: var(--positionX1);
        top: 0;
        height: 100%;
        z-index: 1 !important;
    }

    #sidebar-box[sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar,
    #sidebar-box[sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"] {
        transition: width var(--transition-time) ease var(--delay);
    }

    #sidebar-box[sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"]:not(:hover) #sidebar {
        width: var(--before-width) !important;
    }

    @media (width >= 1200px) {
        #sidebar-box[sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"]:hover #sidebar {
            width: var(--after-width) !important;
        }
    }

    [sidebarcommand*="treestyletab_piro_sakura_ne_jp-sidebar-action"] ~ #sidebar-splitter {
        display: none;
    }
}