SOURCE

<div class="day-text-container">
  <div class="day-text">
    10
  </div>
  <div class="day-text2">
    天
  </div>
</div>

.day-text-container {
  margin-top: 28px;
  display: flex;
  justify-content: center;
  align-items: flex-end;
  border: 1px solid blue;
}

.day-text {
  color: #44b6fe;
  font-size: 84px;
  line-height: 84px;
  font-weight: bold;
  border: 1px solid blue;
}

.day-text2 {
  color: #44b6fe;
  font-size: 36px;
  line-height: 36px;
  border: 1px solid red;
}