* {
  box-sizing: border-box;
}
body {
  text-align: center;
  margin: 0;
  font-family: 'Poppins', sans-serif;
}
.select-birthday {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-bottom: 1px solid #ddd;
  padding: 15px 0 8px;
  position: relative;
}
.select-birthday__text {
  font-size: 21px;
  color: #232323;
}
.select-birthday__day,
.select-birthday__month,
.select-birthday__year {
  font-size: 14px;
  text-transform: capitalize;
  border-color: #c7c7c7;
  color: #555;
}
.select-birthday > *:not(.age) {
  margin: 0 8px;
}
.age {
  font-size: 30px;
  font-weight: 600;
  color: #222;
  position: absolute;
  bottom: -1px;
  transform: translateY(100%);
  left: 0;
  right: 0;
  padding: 60px 10px;
}
.age.bg {
  background-color: #fafafa;
}