a {
    text-decoration: none;//去掉下划线
    color: inherit;
    -webkit-user-select: none;
    -moz-user-select: none;
    user-select: none;
    -webkit-appearance: none;
    -webkit-text-size-adjust: none;
    -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
    -webkit-touch-callout: none;
    border-bottom: none;//去掉下边框（用text-decoration: none;没有用是时候加上）；
    display: block;
    width: 100%;
    height: 40px;
}