HTMLify

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: sans-serif;
}

body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: cyan;
}

.calendar {
  background-color: white;
  width: 40%;
  text-align: center;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
  overflow: hidden;
}

.month {
  margin: 0;
  background-color: blue;
  color: #fff;
  font-weight: bold;
  padding: 10px;
  margin-bottom: 10px;
}

.day {
  font-size: 20px;
  color: darkgray;
}

.day-number {
  font-size: 80px;
  margin: 0;
  font-weight: bold;
}

.year {
  margin: 20px 0;
  font-size: 20px;
  color: darkgray;
  font-weight: 500;
}