Reading through the wiki here and here, you'd have to do the following:
- Create and specify a custom
.css file in the YAML header of your .Rmd file like so:
---
title: "Presentation Ninja"
subtitle: "with xaringan"
author: "Yihui Xie"
date: "2016/12/12"
output:
xaringan::moon_reader:
css: ["default", "my-theme.css"]
lib_dir: libs
nature:
highlightStyle: github
highlightLines: true
---
- Within your
my-theme.css file, have something like:
.inverse, .hljs-github {
background-image: url(https://upload.wikimedia.org/wikipedia/commons/3/39/Naruto_Shiki_Fujin.svg); /* Change this to the url of the image you want as your background */
background-size: cover;
}
To me it seems the .inverse and .hljs-github classes should cover all your slides.