index.css

body{
	background-color: #2980B9;
}

h1{
	font-size: 30px;
	color: #5CCDC9;
	position: relative;
	left:50%;
}

ul{
	display: inline-block;
	text-align: left;
	padding: 50px;
}
ul li{
	margin: 10px;
	font-size: 24px;
	font-weight: 500;
	color: #5CCDC9;
}
.text_field{
	position: relative;
	left:45%;
	top: 60%;
}
.but{
	position: relative;
	top: 40%;
	left:45%;
}

.conteiner{
	display: flex;
	flex-direction: column;
	height: 100%;
	width: 50%;
	margin: 0 auto;
	justify-content: center;
	top: 50%;
}
.centred{
	height: 60%;
	display: flex;
	flex-direction: column;
}
.conteiner .list{
	flex: 1;
	position: relative;
}
.conteiner .list ul{
	position: absolute;
	left: 0;
	top: 70px;
	right: 0;
	bottom: 0;
	overflow: auto;
}

.conteiner .list ul li:nth-child(2n+1){
	background-color: #fff;
}


input[type="checkbox"]:checked + label {
	text-decoration: line-through;
  }