*{ margin:0; padding:0;}
button:focus{ outline:none}
.btn{ border:0; background:#ccc; padding:10px 20px; cursor:pointer}
.btn.on{ background:#09C;}/*切换你按钮背景*/
.hide{ background:#09C; padding:20px; width:150px; display:none}
.hide.on{ display:block}/*内容显示与否*/