style.css

@import url('https://fonts.googleapis.com/css?family=Oswald:400,700%7cPoppins:300,400,400i,600,600i,700,800,900');
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family:'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}
body {
    display: flex;
    height: 100vh;
    justify-content: center;
    align-items: center;
    padding: 10px;
    background: linear-gradient(135deg, #e67181, rgba(187, 85, 182, 0.6));
}
.container {
    max-width: 700px;
    width: 100%;
    background: #fff
    padding: 25px 30px;
    border-radius: 5px;
}
.container .title {
    font-size: 25px;
    font-weight: 500;
    position: relative;
}
.container .title::before {
    content: ' ';
    position: absolute;
    left: 0;
    bottom: 0;
    height: 3px;
    width: 30px;
    background: linear-gradient (135deg, #71b7e6, #9b58);
}
.container form .user-details 
    display: flex;
    flex-wrap: wrap;
}
form user-details .input-box {
    margin-bottom: 15px;
    width: calc(100% / 2 - 20px);
}
.user-details .input-box .details {
    display: block;
    font-weight: 500;
    margin-bottom: 5px;
}
.user-details .input-box input {
    height: 45px;
    width: 100%;
    outline: none;
    border-radius: 5px;
    border: 1px solid #ccc;
    padding-left: 15px;
    font-size: 16px;
    border-bottom-width: 2p;
    transition: all 0.3s ease;
}
user-details input-box input:focus,
.user-details .input-box input:valid {
    border-color: #9b59b6
}
form .gender-details .gender-title {
    font-size: 20px;
    font-weight: 500;
}

form .gender-details .category {
    display: flex;
    width: 80%;
    margin: 14px 0;
    justify-content: space-between;
}
.gender-details .category label {
    display: flex;
    align-items: center;
}
gender-details .category .dot {
    height: 18px;
    width: 18px;
    background: red;
    border-radius: 50%;
    margin-right: 10px;
    border: 5px solid transparent;
    transition: all 0.3s ease;
}

#dot-1:checked~.category label.one,
#dot-2:checked~.category label.two,
#dot-3:checked~.category label .three {
    border-color: #d9d9d9;
    background: #9b59b6;
}
form input[type="radio"] {
    display: none;
}
form .button {
    height: 45px;
    margin: 45px 0;
}
form .button input {
    height: 100%;
    width: 100%;
    outline: none;
    color: #fff;
    border: none;
    font-size: 18px;
    font-weight: 500;
    border-radius: 5px;
    letter-spacing: 1px;
    background: linear-gradient(135deg, #71b7e6,#9b59b6);
}
form .button input:hover {
    background: linear-gradient(-135deg, #71b7e6, #9b59b6);
}
@media (max-width: 584px) {
    .container {
        max-width: 100%;
    }
    form .user-details .input-box {
        margin-bottom: 15px;
        width: 100%;
    }
    form gender-details .category {
        width: 100%;
    }
    .container form .user-details {
        max-height: 300px;
        overflow-y: scroll;
    }
    .user-details::-webkit-scrollbar-button {
        width: 0%;
    }
}