Font size in ioslides markdown presentation title page

问题

Trying to alter the default text size of the title page from an ioslides presentation but failing:

---
title: "My title is a bit too long to fully fit on the title page. I would really like to alter the font size to  provide a better fit. I have limited CSS skills to do so"
author: "My Name"
date: "29 March 2016"
output: 
  ioslides_presentation:
  css: slide.css
---

## R Markdown

This is an R Markdown presentation.

Where my style.css file is:

h1 { font-size: 12px;}

回答1:

First, spacing/indentation/tab is important in YAML (notice the additional tab on the css line):

output: 
  ioslides_presentation:
    css: slide.css

This is not perfect and hopefully somebody else can chime in, but you can adjust .title-slide class with hgroup and h1 tags with:

.title-slide hgroup h1 {
  font-size: 12px;
  letter-spacing: 0;
}

Note: You will want to modify letter-spacing to 0 (as opposed to the original rendered 3px) in the current example.

来源：https://stackoverflow.com/questions/36285680/font-size-in-ioslides-markdown-presentation-title-page