CSSに関するソース
https://meyerweb.com/eric/tools/css/reset/
https://github.com/necolas/normalize.css/
http://ecss.io/
http://www.stubbornella.org/content/2010/06/25/the-media-object-saves-hundreds-of-lines-of-code/
https://philipwalton.github.io/solved-by-flexbox/
http://oocss.org/
https://developer.mozilla.org/en-US/docs/Web/CSS/calc
#css