* {
	margin: auto;
	padding: 0;
	box-sizing: border-box;
}


body {
	width: auto;
    background: #000000;
	position: relative;
	text-align: center;
	padding: 50px;
	margin: 5% 25% 25% 15%;
	border-radius: 100px;
	border: 5px solid white;
	font-family: cursive;
}

label
{
    display:inline-flex;
    width: auto;
	font-family: cursive;
	color:#ffffff;
}
header, p, h1, h3, a {
	width: auto;
    background: #000000;
	position: relative;
	text-align: center;
	color: white;
	padding: 2em;
	margin: 5% 25% 25% 15%;
	border-radius: 100px;
	border: 5px solid white;
	font-family: cursive;
}
.btn {
	background: none;
	width: 500px;
	height: 100px;
	border: 4px solid #ffffff;
	font-size: 20px;
	font-weight: bold;
	color: #ffffff;
	transition: .4s linear;
	position: center;
	top: 30px;
	left: 10px;
	cursor: pointer;
	font-family: cursive;
	border-radius: 10px;
	flex:auto;
}

.btn:hover {
	color: rgb(0, 0, 0);
}

.btn::before {
	content: "";
	position: absolute;
	width: 0px;
	height: 45px;
	top: 0px;
	left: 0px;
	background-color: #ffffff;
	z-index: -1;
	transition: .4s linear;
	border-radius: 0px 0px 10px 0px;
}

.btn:hover::before {
	width: 195px;
}

.cadre {
	scroll-behavior: smooth;
	display: flex;
	color: rgb(240, 240, 240);
	width: 300px;
	padding: 20px 200px 50px 20px;
	background-color: #000000;
	border: 2px solid rgb(255, 255, 255);
	border-radius: 20px;
	font-family: Arial, Helvetica, sans-serif;
	scroll-behavior: smooth;
}

a {
	color: white;
}

input {
	color: rgb(0, 0, 0);
	border-radius: 5px;
	padding: 5px 10px 5px 10px;
}

.env {
	color: rgb(255, 255, 255);
	display: flex;
	background-color: transparent;
	border-radius: none;
	border: none;
	position: relative;
	top: -2px;
	left: 0px;
	width: 195px;
	height: 45px;
	text-align: center;
	display: block;
    width: center;
	font-family: cursive;
}

.env :hover {
	color: white;
}

.env::before {
	color: black;
}
.truc-a-centrer { 
position: absolute; /* postulat de départ */ 
top: 50%; left: 50%; /* à 50%/50% du parent référent */ 
transform: translate(-50%, -50%); /* décalage de 50% de sa propre taille */ 
}    
section {
	display: flex;
	flex-direction: column;
  }