:root {
    --index: calc(1vw + 1vh);
    /*//--text: #fff;*/
    /*// --transition: transform .75s cubic-bezier(.075, .5, 0, 1);*/
}

.main-header {
    position: relative;
}

.main-header::after {
    content: '';
    position: absolute;
    z-index: 100;
    width: 100%;
    height: calc(var(--index) * 10);
    /*//background-image: url(../img/ground.png);*/
    background-size: cover;
    background-repeat: no-repeat;
    background-position: center;
    bottom: calc(var(--index) * -4.5);
}

.layers {
    height: 100vh;
    /*height: 2000px;*/
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    overflow: hidden;
    position: relative;
}

.layer {
    height: 100%;
    width: 100%;
    position: absolute;
    background-size: cover;
    background-position: center;
    will-change: transform;
    z-index: 2;
    transition: var(--transition);
}

/*4*/
.layers__base {
    transform: translate3d(0, calc(var(--scrollTop) / 1.6), 0);
    z-index: 0;
}

/*3*/
.layers__middle3 {
    transform: translate3d(0, calc(var(--scrollTop) / 2.5), 0);
    z-index: 10;
}

/*2*/
.layers__middle2 {
    transform: translate3d(0, calc(var(--scrollTop) / 3.5), 0);
    z-index: 20;
}

/*1*/
.layers__front {
    transform: translate3d(0, calc(var(--scrollTop) / 7.0), 0);
    z-index: 30;
}

.layer__header {
    margin-top: calc(var(--index) * -8);
    z-index: 25;
    text-align: center;
    transform: translate3d(0, calc(var(--scrollTop) * .65), 0);
    transition: var(--transition);
    will-change: transform;
}

.layers__title {
    font-family: Arial, Helvetica, sans-serif;
    font-size: calc(var(--index) * 2.25);
    line-height: calc(var(--index) * 2.25);
    letter-spacing: calc(var(--index) / 3.5);
    color: #ffffff;
    text-transform: uppercase;
    /*opacity: .9;*/
    font-weight: 900;
    text-align: center;
    text-shadow: 0 .25rem 1rem rgba(0, 51, 153, .25), 0 .125rem .125rem rgba(0, 51, 153, .25);
}

.layers__caption {
    font-family: Arial, Helvetica, sans-serif;
    font-size: calc(var(--index) * 0.65);
    line-height: calc(var(--index) * 1.185);
    letter-spacing: calc(var(--index) * 0.35);
    margin-top: calc(var(--index) * 0.30);
    color: #ffffff;
    text-transform: uppercase;
    opacity: .95;
    font-weight: 900;
    text-align: center;
    text-shadow: 0 .25rem 1rem rgba(0, 51, 153, .5), 0 .125rem .125rem rgba(0, 51, 153, .5);
}