.pinlogin .pinlogin-field {
    box-sizing: border-box;
    display: inline-block;
    width: 60px;
    height: 60px;
    padding: 5px;
    margin: 0 10px;
    border: 1px solid #ccc;
    -webkit-border-radius: 2px;
    -moz-border-radius: 2px;
    border-radius: 2px;
    text-align: center;
    font-size: 1.75rem;
}

    .pinlogin .pinlogin-field:first-of-type {
        margin-left: 0;
    }

    .pinlogin .pinlogin-field:last-of-type {
        margin-right: 0;
    }

    .pinlogin .pinlogin-field:read-only {
        border: 1px solid #ddd;
        background: #fafafa;
        cursor: default;
    }

    .pinlogin .pinlogin-field.invalid {
        border: 1px solid red;
        color: red;
    }