Color change in beamer at R markdown

Question

Esteemed,

I'm having trouble putting together a beamer presentation. I would like to put the title, the footer and the items in green tones.

I appreciate any help.

title: "long title"
date: "10/10/2020"
output: 
  beamer_presentation:
    theme: "CambridgeUS"
    keep_tex: true
header-includes:
  - \AtBeginDocument{\title[short title]{"long title"}}
  - \AtBeginDocument{\author[author1; author2; author3; author4]{author1\\author2\\author3\\author4}}
  - \addtobeamertemplate{headline}{\includegraphics[width=\paperwidth,height=2cm,page=2]{img.png}}
 
---
# Introduction   

* text1;  

* text2;  
 
* text3;

* text4.

Answer 1

Something like the following should do it. You can use the \definecolor function in the xcolor package to define named colors that can be used in setbeamercolor and setbeamertemplate declarations. I didn't have the image you were trying to include, so I removed that line from the code below. I'm also not sure what footer you are talking about.

---
title: "long title"
date: "10/10/2020"
output: 
  beamer_presentation:
  theme: "CambridgeUS"
keep_tex: true
header-includes:
  - \AtBeginDocument{\title[short title]{"long title"}}
  - \AtBeginDocument{\author[author1; author2; author3; author4]{author1\\author2\\author3\\author4}}
  - \usepackage{xcolor}
  - \definecolor{olive}{rgb}{0.3, 0.4, .1}
  - \setbeamercolor{itemize/enumerate body}{fg=olive}
  - \setbeamercolor{title}{fg=green}
  - \setbeamercolor{frametitle}{fg=green}
  - \setbeamertemplate{itemize item}{\color{green}$\blacktriangleright$}
  - \setbeamertemplate{itemize subitem}{\color{green}$\blacktriangleright$}


---


# Introduction   

* text1;  

* text2;  

* text3;

* text4.

There are a couple of useful resources this wikibook identifies a number of different elements whose colors can be set with the setbeamercolor declaration. I also made use of this post in my answer.