Adding a vertical dotted line to a shiny slider

I currently have two sliders that I use to reactively plot points on a plotly graph in shiny. The sliders are called "x" and "y". I then feed these values into an optimizer that gives me a solution. On my "x" and "y" sliders, I would like to add a vertical dotted line and text that tells the x-value and y-value of the optimized point. Note: I do not want this dotted line to be able to move from a user's input. The purpose of this line is to tell the user how much the current solution achieves on the current goal. I already know how to reactively update the slider, so I am mainly just looking for the aesthetic component of adding the line. If adding a line is too difficult, I wouldn't mind just a marker, as long as the intended information is conveyed.

Adding a line to the slider like this

A simplified version of my code looks like this.

library(shiny)
library(shinydashboard)
library(shinyjs)



ui <- fluidPage(

  shiny::sliderInput(inputId = 'x', 
                     label = "X Slider",
                     value = 0.9,
                     pre = paste("Goal x: "),
                     min = 0,
                     max = 1
  ),

  shiny::sliderInput(inputId = 'y', 
                     label = "Y Slider",
                     value = 0.5, 
                     pre = paste("Goal y: "),
                     min = 0,
                     max = 1
  )
)

server <- function(input, output) {}

shinyApp(ui = ui, server = server)