R Shiny fluidRow columns. One line on mobile?

Question

Here are two numeric input form fields. On a big screen browser the fields are side by side, which is what I want.

However, when I simulate an iPhone SE using Chrome > Inspect > Dimensions iPhone SE 375 x 667 the fields are now on separate rows even though it appears that there is enough space to keep them on the same row. This occurs even if the labels are one character and the form fields are 10px in length.

How is it possible to keep the two fields on the same row on mobile, such as an iPhone SE?

library("shiny") 
library("shinyWidgets")

form_field_width <- "80px"

ui <- shinyUI(fluidPage(
  fluidRow(
    column(2, HTML('<b>AAA</b>')),
    column(3, autonumericInput(
      inputId = "gas", 
      label = NULL, 
      value = 50, 
      currencySymbol = "$",
      currencySymbolPlacement = "p",
      decimalPlaces = 0,
      minimumValue = 0,
      maximumValue = 5000,
      width = form_field_width)
    ),
    column(2, HTML('<b>BBBB</b>')), 
    column(3, autonumericInput(
      inputId = "grocery", 
      label = NULL, 
      value = 2000, 
      currencySymbol = "$",
      currencySymbolPlacement = "p",
      decimalPlaces = 0,
      minimumValue = 0,
      maximumValue = 9000,
      width = form_field_width)
    ))
))

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

shinyApp(ui, server)