<form action="//css-tricks.us2.list-manage.com/subscribe/post?u=155f5a9ccc4e24c318130cace&amp;id=197f127a68" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank">
	<h2>Subscribe to our mailing list</h2>
	<div>
		<label for="mce-FNAME">First Name</label>
		<input type="text" name="FNAME" id="mce-FNAME">
	</div>
	<div>
		<label for="mce-EMAIL">Email Address</label>
		<input type="email" name="EMAIL" id="mce-EMAIL" title="The domain portion of the email address is invalid (the portion after the @)." pattern="^([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x22([^\x0d\x22\x5c\x80-\xff]|\x5c[\x00-\x7f])*\x22)(\x2e([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x22([^\x0d\x22\x5c\x80-\xff]|\x5c[\x00-\x7f])*\x22))*\x40([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x5b([^\x0d\x5b-\x5d\x80-\xff]|\x5c[\x00-\x7f])*\x5d)(\x2e([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x5b([^\x0d\x5b-\x5d\x80-\xff]|\x5c[\x00-\x7f])*\x5d))*(\.\w{2,})+$" required>
	</div>
    <div style="position: absolute; left: -5000px;" aria-hidden="true"><input type="text" name="b_f2d244c0df42a0431bd08ddea_aeaa9dd034" tabindex="-1" value=""></div>
    <div><input type="submit" value="Subscribe" name="subscribe" id="mc-embedded-subscribe" class="button"></div>
</form>
body {
	font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif;
	font-size: 112.5%;
	margin-left: auto;
	margin-right: auto;
	max-width: 40em;
	width: 88%;
}

/**
 * Form Styles
 */
label {
	display: block;
	font-weight: bold;
	margin-bottom: 0.5em;
}

.label-normal {
	font-weight: normal;
}

.pattern {
	color: #808080;
	font-size: 0.8em;
	font-weight: normal;
}

.supports-color .color,
.supports-date .date,
.supports-time .time,
.supports-month .mont {
	display: none;
}

input,
select {
	display: inline-block;
	font-size: 1em;
	margin-bottom: 1em;
	padding: 0.25em 0.5em;
	width: 100%;
}

[type="checkbox"],
[type="radio"] {
	margin-bottom: 0.5em;
	width: auto;
}

.button {
	background-color: #0088cc;
	border: 1px solid #0088cc;
	border-radius: 1px;
	color: #ffffff;
	display: inline-block;
	font-size: 0.9375em;
	font-weight: normal;
	line-height: 1.2;
	margin-right: 0.3125em;
	margin-bottom: 0.3125em;
	padding: 0.5em 0.6875em;
	width: auto;
}

.button:active,
.button:focus,
.button:hover {
	background-color: #005580;
	border-color: #005580;
	color: #ffffff;
	text-decoration: none;
}

.button:active {
	box-shadow: inset 0 0.15625em 0.25em rgba(0, 0, 0, 0.15), 0 1px 0.15625em rgba(0, 0, 0, 0.05);
}

/**
 * Errors
 */
.error {
	border-color: red;
}

.error-message {
	color: red;
	font-style: italic;
	margin-bottom: 1em;
}
// A Validity State Polyfill
;(function (window, document, undefined) {

	'use strict';

	// Make sure that ValidityState is supported in full (all features)
	var supported = function () {
		var input = document.createElement('input');
		return ('validity' in input && 'badInput' in input.validity && 'patternMismatch' in input.validity && 'rangeOverflow' in input.validity && 'rangeUnderflow' in input.validity && 'stepMismatch' in input.validity && 'tooLong' in input.validity && 'tooShort' in input.validity && 'typeMismatch' in input.validity && 'valid' in input.validity && 'valueMissing' in input.validity);
	};

	/**
	 * Generate the field validity object
	 * @param  {Node]} field The field to validate
	 * @return {Object}      The validity object
	 */
	var getValidityState = function (field) {

		// Variables
		var type = field.getAttribute('type') || input.nodeName.toLowerCase();
		var isNum = type === 'number' || type === 'range';
		var length = field.value.length;
		var valid = true;

		// If radio group, get selected field
		if (field.type === 'radio' && field.name) {
			var group = document.getElementsByName(field.name);
			if (group.length > 0) {
				for (var i = 0; i < group.length; i++) {
					if (group[i].form === field.form && field.checked) {
						field = group[i];
						break;
					}
				}
			}
		}

		// Run validity checks
		var checkValidity = {
			badInput: (isNum && length > 0 && !/[-+]?[0-9]/.test(field.value)), // value of a number field is not a number
			patternMismatch: (field.hasAttribute('pattern') && length > 0 && new RegExp(field.getAttribute('pattern')).test(field.value) === false), // value does not conform to the pattern
			rangeOverflow: (field.hasAttribute('max') && isNum && field.value > 0 && Number(field.value) > Number(field.getAttribute('max'))), // value of a number field is higher than the max attribute
			rangeUnderflow: (field.hasAttribute('min') && isNum && field.value > 0 && Number(field.value) < Number(field.getAttribute('min'))), // value of a number field is lower than the min attribute
			stepMismatch: (isNum && ((field.hasAttribute('step') && field.getAttribute('step') !== 'any' && Number(field.value) % Number(field.getAttribute('step')) !== 0) || (!field.hasAttribute('step') && Number(field.value) % 1 !== 0))), // value of a number field does not conform to the stepattribute
			tooLong: (field.hasAttribute('maxLength') && field.getAttribute('maxLength') > 0 && length > parseInt(field.getAttribute('maxLength'), 10)), // the user has edited a too-long value in a field with maxlength
			tooShort: (field.hasAttribute('minLength') && field.getAttribute('minLength') > 0 && length > 0 && length < parseInt(field.getAttribute('minLength'), 10)), // the user has edited a too-short value in a field with minlength
			typeMismatch: (length > 0 && ((type === 'email' && !/^([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x22([^\x0d\x22\x5c\x80-\xff]|\x5c[\x00-\x7f])*\x22)(\x2e([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x22([^\x0d\x22\x5c\x80-\xff]|\x5c[\x00-\x7f])*\x22))*\x40([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x5b([^\x0d\x5b-\x5d\x80-\xff]|\x5c[\x00-\x7f])*\x5d)(\x2e([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x5b([^\x0d\x5b-\x5d\x80-\xff]|\x5c[\x00-\x7f])*\x5d))*$/.test(field.value)) || (type === 'url' && !/^(?:(?:https?|HTTPS?|ftp|FTP):\/\/)(?:\S+(?::\S*)?@)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-zA-Z\u00a1-\uffff0-9]-*)*[a-zA-Z\u00a1-\uffff0-9]+)(?:\.(?:[a-zA-Z\u00a1-\uffff0-9]-*)*[a-zA-Z\u00a1-\uffff0-9]+)*)(?::\d{2,5})?(?:[\/?#]\S*)?$/.test(field.value)))), // value of a email or URL field is not an email address or URL
			valueMissing: (field.hasAttribute('required') && (((type === 'checkbox' || type === 'radio') && !field.checked) || (type === 'select' && field.options[field.selectedIndex].value < 1) || (type !=='checkbox' && type !== 'radio' && type !=='select' && length < 1))) // required field without a value
		};

		// Check if any errors
		for (var key in checkValidity) {
			if (checkValidity.hasOwnProperty(key)) {
				// If there's an error, change valid value
				if (checkValidity[key]) {
					valid = false;
					break;
				}
			}
		}

		// Add valid property to validity object
		checkValidity.valid = valid;

		// Return object
		return checkValidity;

	};

	// If the full set of ValidityState features aren't supported, polyfill
	// if (!supported()) {
		Object.defineProperty(HTMLInputElement.prototype, 'validity', {
			get: function ValidityState() {
				return getValidityState(this);
			},
			configurable: true,
		});
	// }

})(window, document);


/*
 * classList.js: Cross-browser full element.classList implementation.
 * 1.1.20170427
 *
 * By Eli Grey, http://eligrey.com
 * License: Dedicated to the public domain.
 *   See https://github.com/eligrey/classList.js/blob/master/LICENSE.md
 */

/*global self, document, DOMException */

/*! @source http://purl.eligrey.com/github/classList.js/blob/master/classList.js */

if ("document" in self) {

// Full polyfill for browsers with no classList support
// Including IE < Edge missing SVGElement.classList
if (!("classList" in document.createElement("_")) 
	|| document.createElementNS && !("classList" in document.createElementNS("http://www.w3.org/2000/svg","g"))) {

(function (view) {

"use strict";

if (!('Element' in view)) return;

var
	  classListProp = "classList"
	, protoProp = "prototype"
	, elemCtrProto = view.Element[protoProp]
	, objCtr = Object
	, strTrim = String[protoProp].trim || function () {
		return this.replace(/^\s+|\s+$/g, "");
	}
	, arrIndexOf = Array[protoProp].indexOf || function (item) {
		var
			  i = 0
			, len = this.length
		;
		for (; i < len; i++) {
			if (i in this && this[i] === item) {
				return i;
			}
		}
		return -1;
	}
	// Vendors: please allow content code to instantiate DOMExceptions
	, DOMEx = function (type, message) {
		this.name = type;
		this.code = DOMException[type];
		this.message = message;
	}
	, checkTokenAndGetIndex = function (classList, token) {
		if (token === "") {
			throw new DOMEx(
				  "SYNTAX_ERR"
				, "An invalid or illegal string was specified"
			);
		}
		if (/\s/.test(token)) {
			throw new DOMEx(
				  "INVALID_CHARACTER_ERR"
				, "String contains an invalid character"
			);
		}
		return arrIndexOf.call(classList, token);
	}
	, ClassList = function (elem) {
		var
			  trimmedClasses = strTrim.call(elem.getAttribute("class") || "")
			, classes = trimmedClasses ? trimmedClasses.split(/\s+/) : []
			, i = 0
			, len = classes.length
		;
		for (; i < len; i++) {
			this.push(classes[i]);
		}
		this._updateClassName = function () {
			elem.setAttribute("class", this.toString());
		};
	}
	, classListProto = ClassList[protoProp] = []
	, classListGetter = function () {
		return new ClassList(this);
	}
;
// Most DOMException implementations don't allow calling DOMException's toString()
// on non-DOMExceptions. Error's toString() is sufficient here.
DOMEx[protoProp] = Error[protoProp];
classListProto.item = function (i) {
	return this[i] || null;
};
classListProto.contains = function (token) {
	token += "";
	return checkTokenAndGetIndex(this, token) !== -1;
};
classListProto.add = function () {
	var
		  tokens = arguments
		, i = 0
		, l = tokens.length
		, token
		, updated = false
	;
	do {
		token = tokens[i] + "";
		if (checkTokenAndGetIndex(this, token) === -1) {
			this.push(token);
			updated = true;
		}
	}
	while (++i < l);

	if (updated) {
		this._updateClassName();
	}
};
classListProto.remove = function () {
	var
		  tokens = arguments
		, i = 0
		, l = tokens.length
		, token
		, updated = false
		, index
	;
	do {
		token = tokens[i] + "";
		index = checkTokenAndGetIndex(this, token);
		while (index !== -1) {
			this.splice(index, 1);
			updated = true;
			index = checkTokenAndGetIndex(this, token);
		}
	}
	while (++i < l);

	if (updated) {
		this._updateClassName();
	}
};
classListProto.toggle = function (token, force) {
	token += "";

	var
		  result = this.contains(token)
		, method = result ?
			force !== true && "remove"
		:
			force !== false && "add"
	;

	if (method) {
		this[method](token);
	}

	if (force === true || force === false) {
		return force;
	} else {
		return !result;
	}
};
classListProto.toString = function () {
	return this.join(" ");
};

if (objCtr.defineProperty) {
	var classListPropDesc = {
		  get: classListGetter
		, enumerable: true
		, configurable: true
	};
	try {
		objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
	} catch (ex) { // IE 8 doesn't support enumerable:true
		// adding undefined to fight this issue https://github.com/eligrey/classList.js/issues/36
		// modernie IE8-MSW7 machine has IE8 8.0.6001.18702 and is affected
		if (ex.number === undefined || ex.number === -0x7FF5EC54) {
			classListPropDesc.enumerable = false;
			objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
		}
	}
} else if (objCtr[protoProp].__defineGetter__) {
	elemCtrProto.__defineGetter__(classListProp, classListGetter);
}

}(self));

}

// There is full or partial native classList support, so just check if we need
// to normalize the add/remove and toggle APIs.

(function () {
	"use strict";

	var testElement = document.createElement("_");

	testElement.classList.add("c1", "c2");

	// Polyfill for IE 10/11 and Firefox <26, where classList.add and
	// classList.remove exist but support only one argument at a time.
	if (!testElement.classList.contains("c2")) {
		var createMethod = function(method) {
			var original = DOMTokenList.prototype[method];

			DOMTokenList.prototype[method] = function(token) {
				var i, len = arguments.length;

				for (i = 0; i < len; i++) {
					token = arguments[i];
					original.call(this, token);
				}
			};
		};
		createMethod('add');
		createMethod('remove');
	}

	testElement.classList.toggle("c3", false);

	// Polyfill for IE 10 and Firefox <24, where classList.toggle does not
	// support the second argument.
	if (testElement.classList.contains("c3")) {
		var _toggle = DOMTokenList.prototype.toggle;

		DOMTokenList.prototype.toggle = function(token, force) {
			if (1 in arguments && !this.contains(token) === !force) {
				return force;
			} else {
				return _toggle.call(this, token);
			}
		};

	}

	testElement = null;
}());

}


// Add the novalidate attribute when the JS loads
var forms = document.querySelectorAll('.validate');
for (var i = 0; i < forms.length; i++) {
    forms[i].setAttribute('novalidate', true);
}


// Validate the field
var hasError = function (field) {

    // Don't validate submits, buttons, file and reset inputs, and disabled fields
    if (field.disabled || field.type === 'file' || field.type === 'reset' || field.type === 'submit' || field.type === 'button') return;

    // Get validity
    var validity = field.validity;

    // If valid, return null
    if (validity.valid) return;

    // If field is required and empty
    if (validity.valueMissing) return 'Please fill out this field.';

    // If not the right type
    if (validity.typeMismatch) {

        // Email
        if (field.type === 'email') return 'Please enter an email address.';

        // URL
        if (field.type === 'url') return 'Please enter a URL.';

    }

    // If too short
    if (validity.tooShort) return 'Please lengthen this text to ' + field.getAttribute('minLength') + ' characters or more. You are currently using ' + field.value.length + ' characters.';

    // If too long
    if (validity.tooLong) return 'Please shorten this text to no more than ' + field.getAttribute('maxLength') + ' characters. You are currently using ' + field.value.length + ' characters.';

    // If pattern doesn't match
    if (validity.patternMismatch) {

        // If pattern info is included, return custom error
        if (field.hasAttribute('title')) return field.getAttribute('title');

        // Otherwise, generic error
        return 'Please match the requested format.';

    }

    // If number input isn't a number
    if (validity.badInput) return 'Please enter a number.';

    // If a number value doesn't match the step interval
    if (validity.stepMismatch) return 'Please select a valid value.';

    // If a number field is over the max
    if (validity.rangeOverflow) return 'Please select a value that is no more than ' + field.getAttribute('max') + '.';

    // If a number field is below the min
    if (validity.rangeUnderflow) return 'Please select a value that is no less than ' + field.getAttribute('min') + '.';

    // If all else fails, return a generic catchall error
    return 'The value you entered for this field is invalid.';

};


// Show an error message
var showError = function (field, error) {

    // Add error class to field
    field.classList.add('error');
  
    // If the field is a radio button and part of a group, error all and get the last item in the group
    if (field.type === 'radio' && field.name) {
        var group = field.form.querySelectorAll('[name="' + field.name + '"]');
        if (group.length > 0) {
            for (var i = 0; i < group.length; i++) {
                group[i].classList.add('error');
            }
            field = group[group.length - 1];
        }
    }

    // Get field id or name
    var id = field.id || field.name;
    if (!id) return;

    // Check if error message field already exists
    // If not, create one
    var message = field.form.querySelector('.error-message#error-for-' + id );
    if (!message) {
        message = document.createElement('div');
        message.className = 'error-message';
        message.id = 'error-for-' + id;
        
        // If the field is a radio button or checkbox, insert error after the label
        var label;
        if (field.type === 'radio' || field.type ==='checkbox') {
            label = field.form.querySelector('label[for="' + id + '"]') || field.parentNode;
            if (label) {
                label.parentNode.insertBefore( message, label.nextSibling );
            }
        }

        // Otherwise, insert it after the field
        if (!label) {
            field.parentNode.insertBefore( message, field.nextSibling );
        }

    }
    
    // Add ARIA role to the field
    field.setAttribute('aria-describedby', 'error-for-' + id);

    // Update error message
    message.innerHTML = error;

    // Show error message
    message.style.display = 'block';
    message.style.visibility = 'visible';

};


// Remove the error message
var removeError = function (field) {

    // Remove error class to field
    field.classList.remove('error');
    
    // Remove ARIA role from the field
    field.removeAttribute('aria-describedby');

    // If the field is a radio button and part of a group, remove error from all and get the last item in the group
    if (field.type === 'radio' && field.name) {
        var group = field.form.querySelectorAll('[name="' + field.name + '"]');
        if (group.length > 0) {
            for (var i = 0; i < group.length; i++) {
                group[i].classList.remove('error');
            }
            field = group[group.length - 1];
        }
    }

    // Get field id or name
    var id = field.id || field.name;
    if (!id) return;
    

    // Check if an error message is in the DOM
    var message = field.form.querySelector('.error-message#error-for-' + id + '');
    if (!message) return;

    // If so, hide it
    message.innerHTML = '';
    message.style.display = 'none';
    message.style.visibility = 'hidden';

};


// Listen to all blur events
document.addEventListener('blur', function (event) {

    // Only run if the field is in a form to be validated
    if (!event.target.form.classList.contains('validate')) return;

    // Validate the field
    var error = hasError(event.target);
  
    // If there's an error, show it
    if (error) {
        showError(event.target, error);
        return;
    }

    // Otherwise, remove any existing error message
    removeError(event.target);

}, true);


// Check all fields on submit
document.addEventListener('submit', function (event) {

    // Only run on forms flagged for validation
    if (!event.target.classList.contains('validate')) return;

    // Prevent form from submitting
    event.preventDefault();

    // Get all of the form elements
    var fields = event.target.elements;

    // Validate each field
    // Store the first field with an error to a variable so we can bring it into focus later
    var error, hasErrors;
    for (var i = 0; i < fields.length; i++) {
        error = hasError(fields[i]);
        if (error) {
            showError(fields[i], error);
            if (!hasErrors) {
                hasErrors = fields[i];
            }
        }
    }

    // If there are errrors, don't submit form and focus on first element with error
    if (hasErrors) {
        hasErrors.focus();
    }

    // Otherwise, let the form submit normally
    // You could also bolt in an Ajax form submit process here

}, false);

External CSS

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External JavaScript

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