body{
    height: 100%;
    padding: 0;
    margin: 0;
}

div{
    box-sizing: border-box;
}

/*包含以下五种的链接*/
a {
    text-decoration: none;
}
/*正常的未被访问过的链接*/
a:link {
    text-decoration: none;
}
/*已经访问过的链接*/
a:visited {
    text-decoration: none;
}
/*鼠标划过(停留)的链接*/
a:hover {
    text-decoration: none;
}
/* 正在点击的链接，鼠标在元素上按下还没有松开*/
a:active {
    text-decoration: none;
}
/* 获得焦点的时候 鼠标松开时显示的颜色*/
a:focus {
    text-decoration: none;
}

.flex-between{
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.flex-around{
    display: flex;
    justify-content: space-around;
    align-items: center;
}
.flex-start{
    display: flex;
    justify-content: flex-start;
    align-items: center;
}
.flex-end{
    display: flex;
    justify-content: flex-end;
    align-items: center;
}
.flex-center{
    display: flex!important;
    justify-content: center!important;
    align-items: center;
}
.flex-col{
    flex-direction: column;
}
/*  -- 内外边距 -- */

.margin-0 {
    margin: 0;
}

.margin-xs {
    margin: 10px;
}

.margin-sm {
    margin: 20px;
}

.margin {
    margin: 30px;
}

.margin-lg {
    margin: 40px;
}

.margin-xl {
    margin: 50px;
}

.margin-top-xs {
    margin-top: 10px;
}

.margin-top-sm {
    margin-top: 20px;
}

.margin-top {
    margin-top: 30px;
}

.margin-top-lg {
    margin-top: 40px;
}

.margin-top-xl {
    margin-top: 50px;
}

.margin-right-xs {
    margin-right: 10px;
}

.margin-right-sm {
    margin-right: 20px;
}

.margin-right {
    margin-right: 30px;
}

.margin-right-lg {
    margin-right: 40px;
}

.margin-right-xl {
    margin-right: 50px;
}

.margin-bottom-xs {
    margin-bottom: 10px;
}

.margin-bottom-sm {
    margin-bottom: 20px;
}

.margin-bottom {
    margin-bottom: 30px;
}

.margin-bottom-lg {
    margin-bottom: 40px;
}

.margin-bottom-xl {
    margin-bottom: 50px;
}

.margin-left-xs {
    margin-left: 10px;
}

.margin-left-sm {
    margin-left: 20px;
}

.margin-left {
    margin-left: 30px;
}

.margin-left-lg {
    margin-left: 40px;
}

.margin-left-xl {
    margin-left: 50px;
}

.margin-lr-xs {
    margin-left: 10px;
    margin-right: 10px;
}

.margin-lr-sm {
    margin-left: 20px;
    margin-right: 20px;
}

.margin-lr {
    margin-left: 30px;
    margin-right: 30px;
}

.margin-lr-lg {
    margin-left: 40px;
    margin-right: 40px;
}

.margin-lr-xl {
    margin-left: 50px;
    margin-right: 50px;
}

.margin-tb-xs {
    margin-top: 10px;
    margin-bottom: 10px;
}

.margin-tb-sm {
    margin-top: 20px;
    margin-bottom: 20px;
}

.margin-tb {
    margin-top: 30px;
    margin-bottom: 30px;
}

.margin-tb-lg {
    margin-top: 40px;
    margin-bottom: 40px;
}

.margin-tb-xl {
    margin-top: 50px;
    margin-bottom: 50px;
}