.flex {
    margin: 30px;
    display: flex;
    flex-direction: row;
}
.flex_1 {
    flex: 1 1 auto;
    text-align: center;
}
.full_width {
    width: 100%;
}
.mx_auto {
    margin-left: auto;
    margin-right: auto;
}
.inline_block {
    display: inline-block;
}
.absolute {
    position: absolute;
}
.relative {
    position: relative;
}
.text_center {
    text-align: center;
}
.clear {
    clear: both;
}
.mt_20 {
    margin-top: 20px;
}
.mt_80 {
    margin-top: 80px;
}
.z-1 {
    z-index: 1;
}
.z-0 {
    z-index: 0;
}
.z-10 {
    z-index: 10;
}
.z-20 {
    z-index: 20;
}