styles.css

:root {
  --bg-color: rgb(23, 5, 31);
  --blue: #1c87c5;
  --pink: #ff0095;
  --red: #f52929;
  --margenta: #6e14a1;
  --otp-desp-color: #c5b9b9;
}

body {
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: var(--bg-color);
}
.otp {
  background: rgba(45, 19, 80, 0.3);
  box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.37);
  backdrop-filter: blur(3px);
  -webkit-backdrop-filter: blur(3px);
  border-radius: 10px;
  border: 2px solid rgba(255, 255, 255, 0.4);
  width: 60vw;
  height: 70vh;
  margin: 6% auto;
  text-align: center;
  color: #eee;
}

.otp .otp-title {
  margin: 40px 0;
  font-size: 2.3rem;
}

.otp .otp-desp {
  font-size: 1.3rem;
  color: var(--otp-desp-color);
}

.digit-group{
  display: flex;
  justify-content: center;
  align-items: center;
}

.digit-group input {
  background-color: transparent;
  width: 50px;
  height: 80px;
  border: 2px solid var(--otp-desp-color);
  line-height: 50px;
  text-align: center;
  font-size: 30px;
  font-weight: 200;
  color: #eee;
  margin: 50px 15px;
  overflow: hidden;
  border-radius: 5px;
}

.otp-btn{
  border: 1px solid var(--bg-color);
  width: 20%;
  height: 8%;
  background-color: var(--otp-desp-color);
  border-radius: 10px;
  color: var(--bg-color);
  cursor: pointer;
  box-shadow: inset 2px -2px 8px rgb(34, 34, 34);
}

.circle {
  position: absolute;
  border-radius: 50%;
}

.circle:nth-child(1) {
  background: var(--red);
  filter: blur(130px);
  -webkit-filter: blur(70px);
  left: -5vw;
  top: -5vh;
  height: 250px;
  width: 250px;
}
.circle:nth-child(2) {
  background-color: var(--margenta);
  filter: blur(130px);
  -webkit-filter: blur(40px);
  right: 13vw;
  top: 10vh;
  height: 150px;
  width: 150px;
}
.circle:nth-child(3) {
  background-color: var(--pink);
  filter: blur(130px);
  -webkit-filter: blur(40px);
  left: 10vw;
  bottom: 5vh;
  height: 250px;
  width: 250px;
}
.circle:nth-child(4) {
  background-color: var(--blue);
  filter: blur(130px);
  -webkit-filter: blur(90px);
  right: -5vw;
  bottom: -10vh;
  height: 325px;
  width: 325px;
}

@media only screen and (max-width: 600px) {
  .otp{
    width: 90vw;
  }
  .digit-group input{
    height: 40px;
    width: 25px;
    font-size: 20px;
    margin: 30px 5px;
  }
}