Using Secure Fields leaves you complete control over the styling of your payment form. The card number and CVV fields can be styled individually. For example:

var secureFields = new SecureFields();
var styles = {
    // set style to all elements, JSON accepted too
    "*": "border: 2px solid black;
      background-color: blue; padding: .65em .5em",

    // or with JSON
    //'*': {
    //    border: '2px solid black',
    //    padding: '.65em .5em'       
    //    backgroundColor: 'blue',  // background-color
    //    backgroundImage: 'none',  // background-image
    //    boxSizing: 'border-box',  // box-sizing
    //    WebkitBoxShadow: 'none',  // -webkit-box-shadow
    //    WebkitAppearance: 'none'  // -webkit-appearance
    //}

    // ::hover on all elements
    "*::hover": "-webkit-box-shadow: none;
      -ms-box-shadow: none; -moz-appearance: none; ",

    // set style to one of the elements
    cardNumber: "font-weight: bold;",
    cvv: "color: green;",

    // setting style based on CSS classes (see 'Toggled classes')
    "cardNumber.valid:hover": "background-color: green;",
    "cardNumber.invalid:hover": "background-color: red;",

    // pseudoselectors
    '*:focus': 'border: 1px solid #66AFE9',
    '*:hover': 'border: 1px solid #66AFE9',
    '*::placeholder': 'color: #999999',
    '*:-ms-input-placeholder': 'color: #999999' // thanks MS :( 
};

secureFields.initPay(
     "your merchantId", {
         cardNumber: "cardNumberPlaceholder",
         cvv: "cvvPlaceholder"
     },{
         styles: styles,
         focus: "cardNumber" // or secureFields.focus("cardNumber");
     }
 );

Dynamic styling

The individual fields can also be styled dynamically:

// the card number field
secureFields.setStyle("cardNumber", "border: 1px solid #ccc");

// the CVV field
secureFields.setStyle("cvv", "border: 1px solid #ccc")

Toggled CSS classes

The Secure Fields automatically toggles CSS classes on the input fields based on various user input. For example use "cardNumber.valid:hover": "background-color: green;" to apply different style based classes.

Class name	Description
`valid`	When the field contains valid input.
`invalid`	When the field contains invalid input. For example a wrong card number or CVV Code.
`empty`	When the field is empty.
`identified`	When a supported brand (for example Visa or Mastercard) was detected when typing in the card number field.

Advanced initialization

The initPay / initRegister function allows to set the input type, placeholder value and which field to be focused right from the beginning. The (random) example from below ensures the following:

The CVV field gets initial focus
The CVV field's input type gets set to tel
The placeholder value will be enter your cvv

secureFields.initPay(
    merchantId,
    {
        cardNumber: "cardNumberPlaceholder",
        cvv:  {
            placeholderElementId: "cvvPlaceholder",
            inputType: "tel",
            placeholder: "enter your cvv"
        }
    },{
        styles: styles,
        focus: "cvv"
    }
);

Setting up payment methods

By default all credit cards available in your merchant setup will be accepted. Use the paymentMethods option if there's a need to accept only a subset of card types

secureFields.initPay(
    merchantId,
    {
        cardNumber: "cardNumberPlaceholder",
        cvv:  "cvvPlaceholder"
    },{
        styles: styles,
        paymentMethods: ["ECA", "VIS"]  // allowing MC and Visa only
    }
);

Supported payment methods are: VIS, ECA, AMX, DIN, DIS, JCB, ELO, CUP

Web fonts

Web fonts are supported via the standard @font-face CSS rule. Because of security concerns it is not permitted to link external resources. So, in order to get custom fonts, you need to:

Contact [email protected] and provide the font files (woff, woof2, ttf etc). The files will be uploaded into your merchant id hosted files space.
Reference the font files, by name (no path) in the styles section of the initPay or initRegister call:

var styles = {
    // setting the font-family to both fields
    "*": "font-family: Metamorphous;",
    "@font-face": {
        "*": {
            fontFamily: "Metamorphous",
            fontStyle: "normal",
            fontWeight: 400,
            src: "url('metamorphous.woff2') format('woff2')"
        }        
    }
}