.text-center {
	text-align: center;
}
.container {
	width: 274px;
  margin-left: auto;
  margin-right: auto;
  border: 2px solid blue;
  padding: 0.5em;
}
input[type="button"] {
	width: 50px;
  height: 50px;
  font-weight: 600;
  font-size: 1.1rem;
}
#clear {
	width: 100%;
}
#output {
	height: 50px;
  width: 100%;
  font-size: 2rem;
}