site/_src/_includes/form-contact.html

<form id="form-contact" class="js-parsley" action="//formspree.io/{{ site.email.contact }}" method="POST" accept-charset="UTF-8">
    <p class="form-group">
        <input class="form-control" type="text" id="name" name="name" required>
        <label class="form-label" for="name">Your Name</label>
    </p>
    <p class="form-group">
        <input class="form-control" type="email" id="email" name="_replyto" required>
        <label class="form-label" for="email">Your Email</label>
    </p>
    <p class="form-group">
        <textarea class="form-control" id="comment" name="comment" rows="1" required></textarea>
        <label class="form-label" for="comment">Your Message</label>
    </p>
    <p class="form-group">
        <input class="btn btn-primary" type="submit" value="Send">
    </p>

    <div class="alert alert-success animation-slide-in-from-bottom hide">
        <svg class="alert__icon icon icon-success">
            <use xlink:href="/assets/img/sprite.svg#icon-success"></use>
        </svg>
        <p>
            <strong class="alert__title">Great to hear you’re interested!</strong>
            We’ll get in touch soon.
        </p>
    </div>
    <div class="alert alert-danger hide">
        <svg class="alert__icon icon icon-fail">
            <use xlink:href="/assets/img/sprite.svg#icon-fail"></use>
        </svg>
        <p>
            <strong class="alert__title">Ops, there was an error</strong>
            Would you mind trying again?
        </p>
    </div>

    <input type="hidden" name="_subject" value="New contact form submission" />
</form>