r 中的滑动尺寸 slidy

Question

Using the default RStudio slidy html presentation template creates slides that have figures with fixed size (I believe 7 inches x 5 inches). When viewing on a larger/higher resolution screen, that can leave a lot of empty space (zooming only changes the size of the text, not the figure):

But adding knitr::opts_chunk$set(echo = FALSE, out.width = '100%') to an R chunk in order to auto-scale the figure size results in a figure that's too tall and requires scrolling to see all the content:

Using out.height='100%' instead of out.width='100%' seems to revert to the original size without changing the figure dimensions:

Is there a better way to control slide dimensions and/or the size of content on html slides other than manually specifying the size of content in inches? When I look at example slides online, they all fill the screen very nicely ( eg ). How does one go about actually accomplishing that? Or is the "solution" to just use PDF output?

For reference, here is the default slidy presentation code:

---
title: "Untitled"
author: "Author"
date: "`r Sys.Date()`"
output: slidy_presentation
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
```

## R Markdown

This is an R Markdown presentation. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see <http://rmarkdown.rstudio.com>.

When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document.

## Slide with Bullets

- Bullet 1
- Bullet 2
- Bullet 3

## Slide with R Output

```{r cars, echo = TRUE}
summary(cars)
```

## Slide with Plot

```{r pressure}
plot(pressure)
```

Answer 1

You can define a knitr hook to enclose the figure in a div tag with class myfigure :

```{r setup, include=FALSE}
knitr::knit_hooks$set(myfigure = function(before, options, envir) {
  if(before) {
    "<div class='myfigure'>"
  } else {
    "</div>"
  }
})
```

Then, using CSS, define the height of the elements having the myfigure class in the vh unit (percentage of the viewport):

```{css}
.myfigure { 
  height: 75vh;
}
```

Now use this stuff as follows:

```{r pressure, echo=FALSE, out.width="100%", out.height="100%", myfigure=TRUE}
plot(pressure)
```

Better, instead of using the same height for all elements having the myfigure class, you can define this hook which allows to set the height in the chunk options:

```{r setup, include=FALSE}
knitr::knit_hooks$set(myfigure = function(before, options, envir) {
  if(before) {
    sprintf("<div class='myfigure' style='height:%svh'>", options$myheight)
  } else {
    "</div>"
  }
})
```

And use this hook as follows (remove the above CSS chunk):

```{r pressure, echo=FALSE, out.width="100%", out.height="100%", myfigure=TRUE, myheight="75"}
plot(pressure)
```