Flexdashboard中Shiny滑块显示过小，请求修复为正常尺寸

问题原因 #

你在flexdashboard的.sidebar列中嵌套了Shiny原生的sidebarPanel()组件，这会引发样式冲突——flexdashboard的侧边栏容器本身已自带布局样式，sidebarPanel()的内边距和容器规则会把滑块挤压成迷你尺寸。

修复方案 #

直接移除sidebarPanel()，将sliderInput()直接放在侧边栏的代码块中即可恢复正常样式。同时清理代码中重复的图表定义和渲染逻辑，避免冗余：

修复后的完整代码：

---
title: "Test App"
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: fill
runtime: shiny
---

```{r setup, include=FALSE}
library(flexdashboard)
library(shiny)
library(tidyverse)
library(shinyjs)
library(shinyWidgets)

# Data Set 1
df <- data.frame( 
  cyl = c("4","6","8"),
  Multiplier = c(2,4,6)
)

# Data Set 2
df1 <- mtcars
df1$cyl <- as.factor(df1$cyl)

Column {.sidebar} #

useShinyjs(rmd = TRUE)

selectInput("clusterNum",
  label = h4("Charts"),
  choices = list("Chart1" = "Chart1", "Chart2" = "Chart2"),
  selected = "Chart1"
)

# 移除sidebarPanel，直接放置sliderInput
sliderInput("integer", "Integer:",
            min = 0, max = 8,
            value = 1)

Column {data-width=650} #

Chart #

# First chart
Chart1 <- ggplot(df1, aes(x = wt, y = mpg)) +
  geom_point()

# 合并重复的Chart2逻辑
Chart2 <- reactive({
  dplyr::left_join(df, df1, by = "cyl") %>%
    dplyr::mutate(mpg_new = mpg * Multiplier * input$integer) %>%
    ggplot(aes(x = wt, y = mpg_new)) +
    geom_point()
})

# 只保留一份renderPlot
renderPlot({
  switch(input$clusterNum,
         "Chart1" = Chart1,
         "Chart2" = Chart2()
  )
})

### 额外说明
- flexdashboard的侧边栏通过`Column {.sidebar}`定义，无需再使用Shiny的`sidebarPanel()`，两者布局系统不兼容会导致样式异常。
- 原代码中重复定义了`Chart2`和两次`renderPlot`，清理后可避免逻辑冗余，提升运行效率。

内容的提问来源于stack exchange，提问作者silent_hunter