R markdown ioslides - change kable font size with CSS

Question

I'm trying to fit a large table on one slide. I'm using kable. I tried {.smaller} but it's not quite enough so I thought I'd use a .css but it isn't working either.

I created a sample presentation to illustrate the problem. I tried knitting it and it shows up the same way as in my other presentation (which is quite long which is why I excluded it here)

My code:

---
title: "test"
author: "Test Author"
date: "5 Februar 2018"
output: 
  ioslides_presentation:
    test: presentation.css
---

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


## Test slide

{r}
table <- data.frame(
  index=1:10,
  long_text=c("long text here: asdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf")
)
kable(table)


## Test slide css {.test}

{r}
table <- data.frame(
  index=1:10,
  long_text=c("long text here: asdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf")
)
kable(table)

And my .css:

.test{
   font-size: 50%;
}

Answer 1

You can do this by modifying the css table and td attributes.

Result:

Example CSS and Code:

presentation.css

table.rmdtable td, table th {
    font-size: 40%;
    padding: 1em 0.5em;
    line-height: 18px;
}

rmarkdownfile

---
title: "test"
author: "Test Author"
date: "5 Februar 2018"
output: 
  ioslides_presentation:
    css: presentation.css
---

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

## Test slide

```{r}
table <- data.frame(
  index=1:10,
  long_text=c("long text here: asdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf")
)
kable(table)
```

## Test slide css {.test}

```{r}
table <- data.frame(
  index=1:10,
  long_text=c("long text here: asdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasfasdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf",
    "long text here: asdfghhjoqweqwrqwrqwrasf")
)

kable(table)
```

Explanation

My recommendation is you open the presentation in your browser, for example, chrome. Launch the development tools and play with the css attributes. You can then build this into your presentation .css file.

Recommended Reading:

Rather than modifying the overall slide deck formatting. I'd recommend you read up on applying css formatting to specific slides. For example only your two test slides.

https://bookdown.org/yihui/rmarkdown/custom-css-1.html#slide-ids-and-classes

I hope this points you in the right direction.