Align boxes next to each other using `conditionalPanel` with `bs4Dash`

Question

In shiny using bs4Dash , I want to have a box with different tabs in the main window and a smaller box with the control parameters next to it. And no, I don't want to use the controlbarMenu option if possible.

I took the example from https://stackoverflow.com/a/59074866/6583972 and rendered it in the very nice bs4Dash package - an extension on shinydashboard . Unfortunately I can't get the boxes to align side by side.

Here the code and depending on whether I work without or with fluidRow() there seems to be a bug (see pictures below):

library("shiny")
library("bs4Dash")

ui <- dashboardPage(
  dashboardHeader(title = "Referencing Box"),
  dashboardSidebar(
    sidebarMenu(
      id = "tabs",
      menuItem("First Tab", tabName =  "tab1",
               menuSubItem("Box", tabName = "box"))
    )
  ),
  dashboardBody(
    tabItem(
      tabName = "box",
      fluidRow( # with or without `fluidRow`
        tabBox(
          id = "tb",
          title = "Two Panels",
          width = 9,
          tabPanel(
            value = "p1",
            id = "p1",
            title = "Panel1"
          ),
          tabPanel(
            id = "p2",
            title = "Panel2"
          )
        ),
        conditionalPanel(
          condition = "input.tb == 'p1'",
          box(
            width = 3,
            id = "p3",
            title = "Conditional Panel"
          )
        )
      )  # with or without `fluidRow`
    )
  )
)

server <- function(input, output) { }
shinyApp(ui, server)