Change the line height of the post title in HUGO-Xmin theme

With R blogdown package, it is easy to build a personal website. I like the style of the yihui/hugo-xmin theme for its simplicity. I built a site with the R blogdown package in my folder 'c:/test' on the Windows OS:

install.packages('blogdown')
setwd('c:/test')
blogdown::new_site(theme='yihui/hugo-xmin')

and I wrote the following text into a .md file in c:/test/content/post/ folder:

---
title: "Summer Holiday in Southern France (VIII): Return to Nice (Videos) 带着俩娃游南法 (第十天): 重返尼斯 (视频)"
author: dapeng
date: "2017-08-17 15:22:06"
slug: summer-holiday-in-southern-france-viii-return-to-nice-videos
categories: [cn]
tags: 
  - cn
---

my text.

Then I previewed the site:

blogdown::serve_site()

However, the post title looks like this:

I was wondering how to change the line height in the title, which is too small by default. I added a line-heightcommand in /themes/hugo-xmin/static/css/style.css like this:

.menu, .article-meta, footer { text-align: center; }
.title { font-size: 1.1em; }
footer a { text-decoration: none; }
hr {
  border-style: dashed;
  line-height: 5em;
  color: #ddd;
}

But it did not work.

Thanks for help!