.lt-form .form-fields {
    max-width: 590px;
    margin: 0 auto;
    position: relative;
}
.lt-form .form-fields:before,
.lt-form .form-fields:after {
    content: '';
    position: absolute;
    width: 190px;
    top: -25px;
    bottom: -25px;
    background-image: url(https://fs.getcourse.ru/fileservice/file/download/a/732704/sc/312/h/9b31a7f8700fdffb56f8fb5360f8d69d.png);
    background-repeat: no-repeat;
    background-size: contain;
    background-position: center;
}
.lt-form .form-fields:before {
    right: calc(100% + 13px);
}
.lt-form .form-fields:after {
    left: calc(100% + 13px);
    transform: scaleX(-1);
}
.lt-form .part-userField {
    margin-bottom: 50px !important;
}
.lt-form .part-userField .f-input {
    height: auto;
    padding: 15px 20px;
    border: 1px solid #F0F0F0;
    background: #F2F2F2;
    -webkit-box-shadow: 0px 4px 4px 0px rgba(0, 0, 0, 0.15) inset;
    box-shadow: 0px 4px 4px 0px rgba(0, 0, 0, 0.15) inset;
    color: inherit;
    transition: .3s;
}
.lt-form .part-userField .f-input:focus,
.lt-form .part-userField .f-input:focus-visible {
    outline: none;
    border-color: #404040; 
}

@media (max-width: 1199px) {
    .lt-form .form-fields {
        max-width: 500px;
    }
    .lt-form .part-userField {
        margin-bottom: 30px !important;
    }
}

@media (max-width: 767px) {
    .lt-form .part-userField {
        margin-bottom: 5vw !important;
    }
    .lt-form .part-userField .f-input {
        padding: 4vw 5vw;
        font-size: 100%;
    }
    .lt-form .form-fields {
        max-width: 75vw;
    }
    .lt-form .form-fields:before, .lt-form .form-fields:after {
        width: 45vw;
        top: -5vw;
        bottom: -5vw;
    }
    .lt-form .form-fields:before {
        right: 98%;
    }
    .lt-form .form-fields:after {
        left: 98%;
    }
    .lt-form button.btn.f-btn.btn-success {
        width: 75vw;
    }
}