create a resizable selectInput window in shiny app

Question

I saw a shiny app, here which uses a resizable selectInput but couldn't figure out how it's been developed. I wonder if anybody has any idea?

Answer 1

library(shiny)

css <- "select {resize: vertical; overflow: auto;}"

shinyApp(
  
  ui = fluidPage(
    tags$head(tags$style(HTML(css))),
    selectInput(
      "variable", "Variable:", names(mtcars), selectize = FALSE, size = 5L
    )
  ),
  
  server = function(input, output) {
    
  }
  
)