.parallax {
    height: 500px; /* fallback for older browsers */
    height: 100vh;
    overflow-x: hidden;
    overflow-y: auto;
    -webkit-perspective: 300px;
    perspective: 300px;
}

.parallax__group {
    position: relative;
    height: 500px; /* fallback for older browsers */
    height: 100vh;
    -webkit-transform-style: preserve-3d;
    transform-style: preserve-3d;
}

.parallax__layer {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
}

.parallax__layer--fore {
    -webkit-transform: translateZ(90px) scale(.7);
    transform: translateZ(90px) scale(.7);
    z-index: 1;
}

.parallax__layer--base {
    -webkit-transform: translateZ(0);
    transform: translateZ(0);
    z-index: 4;
}

.parallax__layer--back {
    -webkit-transform: translateZ(-300px) scale(2);
    transform: translateZ(-300px) scale(2);
    z-index: 3;
}

.parallax__layer--deep {
    -webkit-transform: translateZ(-600px) scale(3);
    transform: translateZ(-600px) scale(3);
    z-index: 2;
}

body, html {
    overflow: hidden;
}

body {
    font: 100% / 1.5 Arial;
}

* {
    margin:0;
    padding:0;
}

.parallax {
    font-size: 200%;
}

/* centre the content in the parallax layers */
.title {
    text-align: center;
    position: absolute;
    left: 50%;
    top: 50%;
    -webkit-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
}
#group1 {
    z-index: 5; /* slide over group 2 */
}
#group1 .parallax__layer--back {
    /*background: rgb(102,204,102);*/
    background: url('../img/varsVallee.jpg');
    background-position: center;
}

#group2 {
    z-index: 3; /* slide under groups 1 and 3 */
}
#group2 .parallax__layer--back {
    /*background: rgb(123,210,102);*/
    background: url('../img/lesMenuires.jpg');
    background-position: center;
}

#group3 {
    z-index: 4; /* slide over group 2 and 4 */
}
#group3 .parallax__layer--base {
    background: rgb(153,216,101);
}

#group4 {
    z-index: 2; /* slide under group 3 and 5 */
}
#group4 .parallax__layer--deep {
    /*background: rgb(184,223,101);*/
    background: url('../img/montBlanc.jpg');
    background-position: center;
}

#group5 {
    z-index: 3; /* slide over group 4 and 6 */
}
#group5 .parallax__layer--base {
    background: rgb(214,229,100);
}

#group6 {
    z-index: 2; /* slide under group 5 and 7 */
}
#group6 .parallax__layer--back {
    background: rgb(245,235,100);
}

#group7 {
    z-index: 3; /* slide over group 7 */
}
#group7 .parallax__layer--base {
    background: rgb(255,241,100);
}