@import url('https://fonts.googleapis.com/css?family=Roboto:100,300,400,500,700,900&display=swap');

*{
box-sizing: border-box;
}
body{
overflow: hidden;
display: flex;
<!-- background-color: #333; -->
}

.oe_login_form{
max-width: 350px;
justify-content: center;
align-items: center;
}

.oe_signup_form{
max-width: 350px;
height: auto;
justify-content: center;
align-items: center;
}

.login-Form_confirm{
margin-top: 5px;
width: 355px;
height: auto;
border-radius: 6px;
/* background: #ecf0f3; */
/* padding: 50px 25px 35px 25px;*/
}

.login-Form_validate{
margin-top: 5px;
padding: 14px 8px;
width: 355px;
height: auto;
/* background: #ecf0f3; */
border-radius: 6px;

/*
padding: 50px 35px 35px 35px;
box-shadow: 10px 10px 15px #cbced1,
-10px -10px 15px #cbced1;
*/

}

.sub-title{
    text-align: left;
    font-family: sans-serif;
    font-size: 18px;
    padding-top: 7px;
    <!-- letter-spacing: 3px; -->
}

.validate-button, .confirm-button{
    outline: none;
    border: none;
    cursor: pointer;
    font-family: sans-serif;
    letter-spacing: 1px;
    width: 100%;
    height: 40px;
    border-radius: 6px;
    box-shadow: 3px 3px 8px #cbced1,
    -3px -3px 8px white;
    color: white;
    background: #4F616B;
    /* background: #283682; */
    /* background: #63e06b; */
}


/* .confirm-button:hover{
    background-color: #E31837;
    transform: scale(1.1);
    transition-delay: 200ms;
    transition-duration: 1s;
}
*/

.confirm-button:active{
    background: yellowgreen;
}


/* .validate-button:hover{
    background-color: #E31837;
    transform: scale(1.1);
    transition-delay: 200ms;
    transition-duration: 1s;
}
*/

.validate-button:active{
    background: yellowgreen;
}

.form_fields{
    width: 100%;
    padding: 30px 5px 5px 5px;
}
.fields input{
    border: none;
    outline: none;
    background: none;
    color: #555;
    padding: 11px 3px 12px 3px;
    /* padding: 10px 10px 10px 10px; */
}
 .phone_no_signup, .username{
    margin-bottom: 10px;
    border-radius: 6px;
    box-shadow: 0px 0px 6px #cbced1, 0px 0px 6px #cbced1;
    /* box-shadow: inset 4px 4px 8px #cbced1,
    inset -4px -4px 8px #cbced1; */
    }



<!-- For svg and links  -->

.fields svg{
height: 20px;
margin: 0px 12px -3px 10px;
}

.link_acc{
color: #283682;
}


.link{
padding-top: 15px;
text-align: center;
}

/*
.link a{
text-decoration: none;
color: #aaa;
font-family: sans-serif;
}
*/



/* Media Queries */
@media only screen and (max-width: 600px) {
    /* Styles for small screens */
    .oe_login_form,
    .oe_signup_form,
    .login-Form_confirm,
    .login-Form_validate {
        max-width: 100%;
    }

    .login-Form_confirm,
    .login-Form_validate {
        width: 100%;
       /* font-size: 10px; */
        font-size: 14px;
    }

    .validate-button,
    .confirm-button {
        width: 100%;
        font-size: 15px;
    }
    .link_acc{
        font-size: 15px;
    }
}