body {
  background-color: #bccee0;
  font-family: Arial, Helvetica, sans-serif;
  text-align: center;
}

label {
  display: inline;
  background: linear-gradient(45deg, #19adff, transparent);
  font-size: 1.2rem;
}

input {
  margin: 0.5rem;
  height: 1.5rem;
  font-size: inherit;
  font-weight: 100;
  border-radius: 7px;
}

#check-number {
  display: block;
  margin: 0.5rem;
  height: 2rem;
  font-size: inherit;
  margin-left: 47%;
  border-radius: 10px;
  border: 2px solid cornflowerblue;
  background: transparent;
  color: #19adff;
  cursor: pointer;
}
#check-number:hover {
  color: #022c43;
  border-radius: #022c43;
}

#output-box {
  display: inline;
  margin-left: 3%;
  line-height: 2;
  font-size: larger;
  background: linear-gradient(45deg, #19adff, transparent);
}