* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

.main_div {
  width: 100%;
  height: 100vh;
  position: relative;
}

.box {
  width: 400px;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  padding: 50px;
  background: rgba(0, 0, 0, 0.8);
  border-radius: 10px;
}

.box h1 {
  margin-bottom: 25px;
  color: #fff;
  text-align: center;
  text-transform: capitalize;
}

.box .input-box {
  position: relative;
}

.box .input-box input {
  width: 100%;
  padding: 10px;
  font-size: 16px;
  letter-spacing: 1px;
  color: #fff;
  margin-bottom: 30px;
  border: none;
  border-bottom: 1px solid #fff;
  background: transparent;
  outline: none;
}

.box .input-box label {
  position: absolute;
  top: 0;
  left: 0;
  letter-spacing: 1px;
  padding: 10px 0;
  font-size: 16px;
  color: #fff;
  transition: 0.5s;
}

.box input[type="submit"] {
  background: transparent;
  border: none;
  outline: none;
  color: #fff;
  background: #03a9f4;
  padding: 9px 18px;
  border-radius: 5px;
  font-size: 14px;
}

.box .input-box input:focus ~ label,
.box .input-box input:valid ~ label {
  top: -20px;
  left: 0;
  font-size: 12px;
  color: #03a9f4;
}