input, button, select, textarea {
outline: none;
-webkit-appearance: none;
border-radius: 0;
}
outline: none;去掉chrome浏览器自带的点击input框出现边框情况-webkit-appearance: button;使元素标签看起来像个按钮样式，意思定义了按钮样式
-webkit-appearance: none;去掉按钮样式border-radius: 0;去掉圆角