Hi there,
I also had that question and I did it with this code, I hope it helps you
/* Customizing WPForms */
#wpforms-129-field_2::placeholder, #wpforms-129-field_3::placeholder, #wpforms-129-field_4::placeholder, #wpforms-129-field_5::placeholder,
#wpforms-129-field_6, #wpforms-129-field_7::placeholder {
color: rgba(0, 0, 0, 0.7);
font-size: 16px;
font-weight: 400;
opacity: 1;
}
div.wpforms-container-full input[type=date]:focus, div.wpforms-container-full input[type=datetime]:focus, div.wpforms-container-full input[type=datetime-local]:focus, div.wpforms-container-full input[type=email]:focus, div.wpforms-container-full input[type=month]:focus, div.wpforms-container-full input[type=number]:focus, div.wpforms-container-full input[type=password]:focus, div.wpforms-container-full input[type=range]:focus, div.wpforms-container-full input[type=search]:focus, div.wpforms-container-full input[type=tel]:focus, div.wpforms-container-full input[type=text]:focus, div.wpforms-container-full input[type=time]:focus, div.wpforms-container-full input[type=url]:focus, div.wpforms-container-full input[type=week]:focus, div.wpforms-container-full select:focus, div.wpforms-container-full textarea:focus {
box-shadow: none !important;
}
div.wpforms-container-full input[type=submit]:focus:after, div.wpforms-container-full button[type=submit]:focus:after, div.wpforms-container-full .wpforms-page-button:focus:after {
border: none !important;
}
.wpforms-field-required ~ em, input.wpforms-error ~ em {
display: none !important;
}
.wpforms-field-required ~ em, input.wpforms-error ~ em {
display: none !important;
}
input[type="text"],
input[type="email"],
input[type="tel"],
select,
textarea {
background: none !important;
border-top: 0px !important;
border-left: 0px !important;
border-right: 0px !important;
}