screen and ( min--moz-device-pixel-ratio: 2), only screen and ( -o-min-device-pixel-ratio: 2/1), only screen and ( min-device-pixel-ratio: 2), only screen and ( min-resolution: 2dppx) { CSS code } 要對應各家瀏覽器,必須要寫這麼多行 你也可以用Sass或一些編輯器外掛來幫你補瀏覽器前綴詞(prefix)
查詢瀏覽器支援度 http://caniuse.com/ • 查詢device-pixel-ratio http://bjango.com/articles/min-device-pixel-ratio/ • The Current State of HTML5 Forms http://www.wufoo.com/html5