Css .png来自闪亮应用程序中的knitr breakes flexdashboard

我使用以下代码制作了我的flex仪表板

---
title: "Offline navigation apps"
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: fill
runtime: shiny
---

```{r setup, include=FALSE}
library(flexdashboard)
library(knitr)
```

# Homepage

## Column {data-width=500}

### Introduction
<font size = "6">This dashboard compares reviews on Google Play between 8 different Offline navigation apps. It is divided between 6 main pages and each page shows different kind of analysis. </font><br><br>
<font size = "6">Idea behind this dashboard is easily compare Google Play review data between different apps. With few changes in the underlying code this dashboard can present review data on apps from other industries.</font><br><br>
<font size = "6">Please note that all data in this dashboard is shown only for app reviews with comments (scraped reviews). In other words, reviews without comments (users who have rated the app on a scale from 1 to 5 without leaving a comment) aren’t included in this report.</font><br><br>
<font size = "6">Please read user manual before exploring this dashboard. You can find user manual by clicking the following icon</font><br>
<a href="https://documentcloud.adobe.com/link/review?uri=urn:aaid:scds:US:82c45607-e381-4f1a-b88a-38ded829c139" target=_blank><center>
```{r dpi=10}
include_graphics("document-icon.png")
```
</center></a>
<br><font size = "6">If you like this dashboard or see a way to improve it, please visit my GitHub page by clicking below</font><br>
<a href="https://github.com/sapfa" target=_blank><center>
```{r dpi=10}
include_graphics("github-icon.png")
```
</center></a>

## Column {data-width=250}

### Info

<center><font size = "6"><b>DATA GATHERING METHODOLOGY:</b> <br>Web scraping<br><br>
<b>TIMELINE:</b> <br>15.06.2016 – 15.06.2020.<br><br>
<b>SAMPLE:</b> <br>8 offline navigation apps<br></font></center>


### List of apps with datasources
<b><font size = "6"><a href="https://play.google.com/store/apps/details?id=hr.mireo.arthur&hl=en" target=_blank>Genius Maps</a><br>
<a href="https://play.google.com/store/apps/details?id=com.tomtom.gplay.navapp&hl=en" target=_blank>TomTom</a><br>
<a href="https://play.google.com/store/apps/details?id=com.alk.copilot.mapviewer&hl=en" target=_blank>CoPilot</a><br>
<a href="https://play.google.com/store/apps/details?id=com.navfree.android.OSM.ALL&hl=en" target=_blank>Navmii</a><br>
<a href="https://play.google.com/store/apps/details?id=com.sygic.aura&hl=en" target=_blank>Sygic</a><br>
<a href="https://play.google.com/store/apps/details?id=com.mapswithme.maps.pro&hl=en" target=_blank>maps.me</a><br>
<a href="https://play.google.com/store/apps/details?id=com.waze&hl=en" target=_blank>Waze</a><br>
<a href="https://play.google.com/store/apps/details?id=com.here.app.maps&hl=en" target=_blank>Here</a></b></font>

及

有人知道问题的确切原因吗？我希望将图像保留在我的仪表板上

```{r dpi=10}
include_graphics("document-icon.png")
```

```{r dpi=10}
include_graphics("github-icon.png")
```