body {
  font-family: Arial;
  background-color: hsl(0, 21%, 91%);
  text-align: center;
  padding-top: 50px;
}
.container {
  background: yellow;
  padding: 20px;
  border-radius: 8px;
  width: 500px;
  margin: auto;
}
input {
  padding: 10px;
  width: 70%;
}
button {
  padding: 10px;
}
li {
  text-align: left;
  margin-top: 10px;
  cursor: pointer;
}
.completed {
  text-decoration: line-through;
  color: rgb(171, 3, 3);
}