html5实现的简单进度条效果，进度条非常简单漂亮，无需任何图片，经测试效果相当不错，完全依靠JS代码和HTML5实现。-html5 achieve the effect of a simple progress bar, the progress bar is very simple and beautiful, without any pictures, tested the effect is quite good, fully rely on JS code and HTML5 impl