test/web_enterprise/static/src/legacy/scss/kanban_view.scss

.o_legacy_kanban_view {

    .o_column_quick_create .o_kanban_quick_create {
        input {
            &, &:focus, &:hover {
                background: transparent;
                border-bottom: 1px solid map-get($grays, '600');
            }
        }
    }
}