* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.flex {
    display: flex;
    justify-content: center;
    align-items: center;
}

body {
    color: #333;
}

li {
    list-style: none;
}

a {
    text-decoration: none;
    color: #333;
}

img {
    vertical-align: middle;
}

input {
    outline: none;
    color: #333;
}

.fl {
    float: left;
}

.fr {
    float: right;
}


/* 清除浮动和塌陷 */

.clearfix::before,
.clearfix::after {
    content: '';
    display: table;
}

.clearfix::after {
    clear: both;
}