Why is the layout of a graph from visnetwork in html too small - html

Question

When I render the example-Rmd below, it looks like this (with Chrome, not really a difference to Firefox):
The figure is way too small and if I look at the "real" graphs I need, the height is too small and the ratio height-width is even worse.
Here is a reproducible example:
---
title: "Untitled"
author: "author"
date: "9 Mai 2018"
output: html_document
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```
## Example
Here is a line of text...................................................................................................................................................................................................................................................................
```{r echo=FALSE}
require(visNetwork, quietly = TRUE)
# minimal example
nodes <- data.frame(id = 1:20)
edges <- data.frame(from = sample(c(1:20), 10), to = sample(c(1:20), 10))
visNetwork(nodes, edges, width = "100%", height = "100%") %>%
visNodes() %>%
visOptions(highlightNearest = TRUE) %>%
visInteraction(navigationButtons = TRUE,
dragNodes = FALSE,
dragView = FALSE, zoomView = FALSE) %>%
visEdges(arrows = 'to')
```
Here is another line of text....................................................................................................................................................................................................................................................................

Answer 1

I expected to fix it using some chunk options, such as out.height or fig.height but for some reason they don't.
However you can set a fixed height for the widget itself, simply passing a number to the height argument that will be interpreted as pixels:
```{r echo=FALSE}
require(visNetwork, quietly = TRUE)
# minimal example
nodes <- data.frame(id = 1:20)
edges <- data.frame(from = sample(c(1:20), 10), to = sample(c(1:20), 10))
visNetwork(nodes, edges, width = "100%", height = 700) %>%
visNodes() %>%
visOptions(highlightNearest = TRUE) %>%
visInteraction(navigationButtons = TRUE,
dragNodes = FALSE,
dragView = FALSE, zoomView = FALSE) %>%
visEdges(arrows = 'to')
```