You've checked something wrong. 243 KB is size of checkout copy not including .git directory. Here is fresh checkout:
$ du --apparent-size -hcs *
1.3K 404.html
8.7K CHANGELOG.md
5.6K CONTRIBUTING.md
1.1K LICENSE.md
2.6K README.md
1.1K apple-touch-icon-precomposed.png
416 browserconfig.xml
603 crossdomain.xml
17K css
49K doc
766 favicon.ico
206 humans.txt
4.0K img
1.8K index.html
118K js
78 robots.txt
6.7K tile-wide.png
14K tile.png
232K total
$ du --apparent-size -hcs .
13M .
13M total