html, body, * {
    margin: 0;
    padding: 0;
}
.w1600 {
    width: 1600px;
    margin: 0 auto;
}
.flex {
    display: flex;
}
.flex-justify-between {
    display: flex;
    justify-content: space-between;
}
.flex-justify-around {
    display: flex;
    justify-content: space-around;
}
.flex-align-center {
    display: flex;
    align-items: center;
}
.flex-col {
    display: flex;
    flex-direction: column;
}
.flex-row {
    display: flex;
    flex-direction: row;
}
.flex-wrap {
    display: flex;
    flex-wrap: wrap;
}