4月5日は着てる服を脱いで、全裸に(きゃー)なろうかと思います。
The idea behind this event is to promote Web Standards. Plain and simple. This includes proper use of (x)html, semantic markup, a good hierarchy structure, and of course, a good 'ol play on words. It's time to show off your <body>.
via: CSS Naked Day
Then on April 5th, simply remove all CSS from your website, stripping it entirely of its design.