style.css

*{
  margin: 0;
  padding: 0;
}

body{
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #10101E;
}

.datetime{
  color: #fff;
  background: #10101E;
  font-family: "Segoe UI", sans-serif;
  width: 340px;
  padding: 15px 10px;
  border: 3px solid #2E94E3;
  border-radius: 5px;
  -webkit-box-reflect: below 1px linear-gradient(transparent, rgba(255, 255, 255, 0.1));
  transition: 0.5s;
  transition-property: background, box-shadow;
}

.datetime:hover{
  background: #2E94E3;
  box-shadow: 0 0 30px #2E94E3;
}

.date{
  font-size: 20px;
  font-weight: 600;
  text-align: center;
  letter-spacing: 3px;
}

.time{
  font-size: 60px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.time span:not(:last-child){
  position: relative;
  margin: 0 6px;
  font-weight: 600;
  text-align: center;
  letter-spacing: 3px;
}

.time span:last-child{
  background: #2E94E3;
  font-size: 30px;
  font-weight: 600;
  text-transform: uppercase;
  margin-top: 10px;
  padding: 0 5px;
  border-radius: 3px;
}