Rmardown: Add horizontal scrollbar to avoid truncated output - css

Question

I am trying to print a large table in Rmarkdown and for some reason the output is split up which makes it hard to read.
I would like to add an horizontal scrollbar so it doesn't split. I managed to do it for the vertical axis, but not for the horizontal one.
Here is a sample of code:
---
title: "Test"
output: html_document
---
```{css, echo=FALSE}
.main-container {
max-width: 800px !important;
}
pre {
max-height: 800px !important;
overflow-y: auto !important;
overflow-x: scroll !important;
}
```
```{r}
mdl <- lm(data = iris, Petal.Width ~ Sepal.Length*Sepal.Width*Petal.Length*Species)
summary(mdl)
```
This is how the output looks like:
As you can see, the horizontal scroll bar shows-up but the output is still split-up. I tried with both overflow-x: scroll !important; and max-width: 500px !important; without success.
The problem persists even if I set the .main-container CSS to max-width: 1200px !important; so that there should in principle be enough space for the model to print without splitting-up.
This is what I'm looking for:
Update
As suggested by #Rorschach, I have added the options(width = 160) to the script. This solves the issue in the second case, that is, when the .main-container CSS max-width is large enough (e.g. 800px):
However, if the max-width is not large enough (e.g. 600px) the print is still messed-up:
---
title: "Test"
output: html_document
---
```{css, echo=FALSE}
.main-container {
max-width: 600px !important;
}
pre {
max-height: 800px !important;
overflow-y: auto !important;
overflow-x: scroll !important;
}
```
```{r setup}
options(width = 160)
```
```{r}
mdl <- lm(data = iris, Petal.Width ~ Sepal.Length*Sepal.Width*Petal.Length*Species)
summary(mdl)
```

Answer 1

Not an css expert but the following seems to do the trick:
---
title: "Test"
output: html_document
---
```{css, echo=FALSE}
.main-container {
max-width: 600px !important;
}
pre {
max-height: 800px !important;
overflow-y: auto !important;
overflow-x: scroll !important;
}
pre code {
white-space: pre
}
```
```{r}
options(width=160)
mdl <- lm(data = iris, Petal.Width ~ Sepal.Length*Sepal.Width*Petal.Length*Species)
summary(mdl)
```