kableExtra: Change font size of table footnote - r-markdown

Question

I'd like for my font size in the footnotes to be smaller than the text in the table, but can't figure it out. Is there something similar to kable_styling where I can edit the text and color of rows in the table that can be used for footnotes? I am using RMarkdown to generate the HTML not LateX.
---
title: "Untitled"
output: html_document
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE )
library( kableExtra )
library( knitr )
```
```{r mtcars}
tab_mtcars <- knitr::kable( mtcars[ 1:5 , c( 1:4 )] , format = "html", col.names = c( "MPG", "CYL", "DISP" , "HP" ) , align = "lccc" , escape = F ) %>% kable_styling( full_width = T , bootstrap_options = c( "hover", "condensed" , "bordered"), position = "left") %>% add_header_above( c( "mtcars example" = 5 ) , bold = TRUE ) %>% footnote( general = c( "Here is the footnote where I would like font smaller than above" ), general_title = "Note: ", footnote_as_chunk = T )
```
`r tab_mtcars`

Answer 1

You could use the html <small> tag in the text for the general and general_title parameters of the kabaleExtra::footnote function. See example:
tab_mtcars <-
knitr::kable(
mtcars[1:5 , c(1:4)] ,
format = "html",
col.names = c("MPG", "CYL", "DISP" , "HP") ,
align = "lccc" ,
escape = F
) %>%
kable_styling(
full_width = T ,
bootstrap_options = c("hover", "condensed" , "bordered"),
position = "left"
) %>% add_header_above(c("mtcars example" = 5) , bold = TRUE) %>% footnote(
general = c(
"<small>Here is the footnote where I would like font smaller than above</small>"
),
general_title = "<small>Note: </small>",
footnote_as_chunk = T ,
escape = F
)

Answer 2

There doesn't seem to be a way to control that from kable() that I can see, so you could change the CSS styling. With your YAML as the following:
---
title: "Untitled"
output:
html_document:
css: style.css
---
and a style.css file in the same folder containing some css code:
tfoot {
font-size: 80%;
}