body {
  margin: 10px;
  font-family: Arial, sans-serif;
}

h1 {
  font-size: 24px;
}

p {
  font-size: 16px;
}

/* Chrome, Safari, Edge, Opera */
input::-webkit-outer-spin-button,
input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

/* Fx */
input[type=number] {
  -moz-appearance: textfield;
}

#label {
  display: block;
  margin-bottom: 10px;
}

#month {
  -webkit-appearance: none;
  background-color: transparent;  /* Fx */
  color: black;  /* iOS Safari */
}

#month, #day, #year {
  border: 0;
  font-size: 16px;  /* Prevent zooming on iOS Safari */
}

#day, #year {
  width: 50px;
  margin-left: 5px;
}

#underline {
  display: block;
  width: 220px;
  height: 10px;
  border-bottom: 1px solid lightgray;
}

#tell-me {
  width: 100px;
  height: 40px;
  font-size: 16px;
}

#wikipedia-link {
  display: block;
  font-size: smaller;
}

.error {
  color: red;
}