The file does not exist http://garudareiga.github.io/theme/css/main.css I think it is necessary to checkin on github
Edited
You need to change the file index.html
Of <link rel="stylesheet" href="/theme/css/main.css">
To <link rel="stylesheet" href="theme/css/main.css">
And all links removes "/" start
Otherwise he will for http://garudareiga.github.io instead of http://garudareiga.github.io/devblog/
http://www.coffeecup.com/help/articles/absolute-vs-relative-pathslinks/