我将按照如下方式进行操作，添加一个style标记并向.row元素添加自定义高度。

library(shiny)

ui <-  fluidPage(
  titlePanel("Navlist panel example"),
  tags$style(".row{height: 500px;} .row div:nth-child(1){height: 100%;}"),
  
  navlistPanel(
    "Header",
    tabPanel("First",
             h3("This is the first panel")),
    tabPanel("Second",
             h3("This is the second panel")),
    tabPanel("Third",
             h3("This is the third panel"))
  )
  
)

server <- function(input, output) {
}

shinyApp(ui, server)

PS：请注意，您的应用程序中可以有多行