R shiny bigger window

Can you guys help me, how not to need to scroll, or make the window of the application bigger, so you can see the slider bars and plots at once? Or that slidebar and the plot will be side by side.see picture

Here is the code:

library(deSolve)
library(shiny)


ui <- verticalLayout(

  titlePanel("Zvolte údaje"),


  sliderInput(inputId = "time_values", label = "Počet dnů", value = 10, min = 1, max = 100),
  sliderInput(inputId = "beta", label ="Míra nákazy", value = 0.05, min = 0, max = 1, step = 0.01),
  sliderInput(inputId = "gamma", label ="Míra uzdravení", value = 0.5, min = 0, max = 1, step = 0.1),


  (plotOutput("plot"))
)

server <- function(input, output) {
  sir_equations <- function(time, variables, parameters) {
    with(as.list(c(variables, parameters)), {
      dS <- -beta * I * S
      dI <-  beta * I * S - gamma * I
      dR <-  gamma * I
      return(list(c(dS, dI, dR)))
    })
  }

  initial_values <-  c(S = 1000, I = 1, R = 0)

  sir_values_1 <- reactiveValues(val = data.frame())

  observe({
    sir_values_1$val <- as.data.frame(ode(
      y = initial_values,
      times = seq(0, input$time_values),
      func = sir_equations,
      parms = c(beta=input$beta, gamma=input$gamma) 
    ))
  })

  output$plot <- renderPlot({
    with(sir_values_1$val, {
    plot(sir_values_1$val$time, sir_values_1$val$S, type = "l", col = "blue",
         xlab = "Doba (dny)", ylab = "Počet lidí")
    lines(sir_values_1$val$time, sir_values_1$val$I, col = "red")
    lines(sir_values_1$val$time, sir_values_1$val$R, col = "green")
    legend("right", c("zdraví", "nakažení", "uzdravení"),
           col = c("blue", "red", "green"), lty = 1, bty = "n")
    })
  })
}

shinyApp(ui = ui, server = server)

Thank you