干掉H5audio音频标签的下载按钮
audio::-internal-media-controls-download-button {display:none;}
audio::-webkit-media-controls {overflow: hidden !important}
audio::-webkit-media-controls-enclosure {width: calc(100% + 32px);}
文章来自：http://www.cnblogs.com/qiuzhimutou/p/6690168.html