html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed, 
figure, figcaption, footer, header, hgroup, 
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
    margin: 0;
    padding: 0;
    border: 0;
    font-size: 100%;
    font: inherit;
    vertical-align: baseline;
}
/* HTML5 display-role reset for older browsers */
article, aside, details, figcaption, figure, 
footer, header, hgroup, menu, nav, section {
    display: block;
}

body {
    line-height: 1;
    color: white;
}

body, html, .page {
    height: 100%;
    overflow: hidden;
}

/* Les classes en dessous concernes les transitions */
:last-child {
    margin-bottom: 0;
}

.contenu{
    display:flex;
    flex-basis: auto;
    flex-direction: column;
    text-align: left;
    margin-top:10rem;
    margin-left: 25rem;
    margin-right: 25rem;
    position: static;
    z-index:1;
    background-color: white;
    color: blue;
    border-radius: 10px;
    padding-top: 0.5rem;
}

.collapsible {
    background: none; 
    color: inherit; 
    border: none; 
    padding: 0;  
    cursor: pointer; 
    outline: inherit;
    font-family: acumin-pro-wide, sans-serif;
    font-weight: 900;
    font-style: normal;
    font-size: 80px;
    line-height: inherit;
    margin: auto;
}

.collapsible:hover {
    color: blue;
}    

.why{
    display:flex;
    flex-basis: auto;
    flex-direction: column;
    text-align: left;
    background: rgba(255, 255, 255, 0.5);
    margin-top: 10rem; 
    margin-left: 15rem;
    margin-right: 15rem;
    position: static;
    padding: 2em;
    border-radius: 30px;
}

.contentcollapsible {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.2s ease-out;
}

.page {
    width: 100%;
}

.radio {
    display: none;
    visibility: hidden;
}

.check-label {
    position: sticky;
    border: 1px solid #333;
    color: white;
    background-color: red;
    cursor: pointer;
    display: inline-block;
    text-decoration: none;
    top: 25%;
}

.check-label:hover, .check-label:active {
    background: #555;
    color: #fff;
}
.check-label:focus {
    outline: thin dotted;
}

.section-container {
    -moz-transition: 0.66s all;
    -webkit-transition: 0.66s all;
    transition: 0.66s all;
    -moz-transform: translate(0%, 40%);
    -ms-transform: translate(0%, 40%);
    -o-transform: translate(0%, 40%);
    -webkit-transform: translate(0%, 40%);
    transform: translate(0%, 40%);
    height: 100%;
    opacity: 0;
    overflow: auto;
    position: fixed;
    width: 100%;
    z-index: 1;
}
.section-content {
    -moz-transition: 0.66s all;
    -webkit-transition: 0.66s all;
    transition: 0.66s all;
    visibility: hidden;
}

:checked + .section-container {
    -moz-transform: translate(0%, 0%);
    -ms-transform: translate(0%, 0%);
    -o-transform: translate(0%, 0%);
    -webkit-transform: translate(0%, 0%);
    transform: translate(0%, 0%);
    opacity: 1;
    z-index: 2;
}

:checked + .section-container .section-content {
    visibility: visible;
}

.transition-left {
    -moz-transform: translate(60%, 0%);
    -ms-transform: translate(60%, 0%);
    -o-transform: translate(60%, 0%);
    -webkit-transform: translate(60%, 0%);
    transform: translate(60%, 0%);
}

.transition-right {
    -moz-transform: translate(-60%, 0%);
    -ms-transform: translate(-60%, 0%);
    -o-transform: translate(-60%, 0%);
    -webkit-transform: translate(-60%, 0%);
    transform: translate(-60%, 0%);
}

/* Les classes en dessous concernes l'animation */
.bg-elem {
    display: none; /* élément invisible de base */
    position: fixed; /* position fixe donc ça ne bouge pas avec le scroll */
    z-index: 100;
}

/* pour que les images prennent la taille des div, tu donneras une classe au image dans les div pour le background */
.bg-elem img {
    max-width: 100%;
    max-height: 100%;
}

.show {
    display: flex;
    /*animation: fade-in .3s ease-out;*/
}

.hide {
    display: none;
    /*animation: fade-out .3s ease-out;*/
}

/* les animations : on indique de quel état on commence "from" et l'état final "to" */
@keyframes fade-in {
    from { opacity: 0; transform: translateX(-50%); }
    to { opacity: 1; transform: translateX(0); }
}

@keyframes fade-out {
    from { opacity: 1; }
    to { opacity: 0; transform: translateX(-100%); }
}