2008-12-24 ■ css 幾何学模様を描く〜CSSテクニック〜 http://www.stylish-style.com/csstec/ultimate/border-deco-ex.html スタイルシートテクニック/CSS tips http://www.stylish-style.com/csstec/csstec-top.html CSS tutorial - Using borders to produce angled shapes http://www.howtocreate.co.uk/tutorials/css/slopes