Shiny splitLayout and selectInput issue

Here is a potential fix. It appears that the parent div of the dropdown menu has an overflow: auto style, which blocks the dropdown menu. Changing to visible fixes it.

library(shiny)

server <- function(input, session, output) {

  output$select_1 <- renderUI({
    selectInput("select_input","select", choices = LETTERS)
  })

}

ui <- fluidPage(
  splitLayout(
    uiOutput("select_1"),
    tags$head(tags$style(HTML("
                              .shiny-split-layout > div {
                                overflow: visible;
                              }
                              ")))
  )
)

shinyApp(ui = ui, server = server)

I tried the solution of @Xiongbing Jin, but that didn't fully resolve the issue for me, but pushed my to this solution:

# in ui.R
splitLayout(
  tags$head(tags$style(HTML(".shiny-split-layout > div {overflow: visible;}"))),
  cellWidths = c("0%","50%", "50%"), # note the 0% here at position zero...
  selectInput("A", label = "A LBL",),
  selectInput("B", label = "B LBL")
)