<! if opt.wayland_compositor == "river" then !>
/* GTK is to retarded to realize that some compositors that don't implement deprecated
* protocols do not want client-side decoration. We completely disable titlebars here to compensate. */
headerbar.titlebar.default-decoration {
    background: transparent;
    padding: 0;
    margin: 0 0 -17px 0;
    border: 0;
    min-height: 0;
    font-size: 0;
    box-shadow: none;
}

window.csd,
window.csd decoration {
    box-shadow: none;
}
<! end !>