JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div id="container">
        <div id="left">
            <!--Logo -->
            <img src="../images/ABC_2013.png" alt="Test logo" height="202" width="190" />
            <!--Links -->
            <ul id="navlist">
                <li id="active"><a href="index.htm">HOME</a>
                </li>
                <li><a href="about.htm">ABOUT US</a>
                </li>
                <li><a href="gallery.htm">GALLERY</a>
                </li>
                <li><a href="services.htm">SERVICES</a>
                </li>
                <li><a href="contact.htm">CONTACT</a>
                </li>
            </ul>
        </div>
        <div id="mid">
             <h1> Contact</h1>

            <p>We love hearing from our customers! Use the form below to get in touch about any questions or comments you might have – we’ll reply as quickly as we possibly can. If you would like to talk to us about your eye's or anything you need, please use the form below:</p>
            <form>
                <fieldset id="pi">
                    <legend>Personal Information</legend>
                    <p>
                        <label for="first_name">First name:</label>
                        <input type="text" name="first name" id="first_name" autofocus required>
                        <br>
                    </p>
                    <p>
                        <label for="last_name">Last Name:</label>
                        <input type="text" name="Last Name" id="last_name" required>
                        <br>
                    </p>
                    <p>
                        <label for="email">Email:</label>
                        <input type="email" name="email" id="email" required>
                        <br>
                    </p>
                    <p>
                        <label for="phone">Phone:</label>
                        <input type="text" name="phone" id="phone">
                        <br>
                    </p>
            ...

JavaScript

<!-- Begin
<
script type = "text/javascript" > function _validate() 
    var emVal, fnVal, lnVal, phoneVal, addressVal;
    var _fname = document.getElementById('first_name').value;
    var _lname = document.getElementById('last_name').value;
    var _email = document.getElementById('email').value;
    var _phone = document.getElementById('phone').value;
    var _address = document.getElementById('address').value;
    var _lblError = document.getElementById('lblError');




    if (_email != "" || _email != null) {
        var b = _emailValidator(_email);
        if (b == false) {
            _lblError.innerHTML = "Invalid Email";
            emVal = false;
        } else {
            fnVal = true;
            if (_fname == "" || _fname == null) {
                _lblError.innerHTML = "Enter First Name";
                fnVal = false;
            } else {
                lnVal = true;
                if (_lname == "" || _lname == null) {
                    lblError.innerHTML = "Enter Last Name";
                    lnVal = false;
                } else {
                    phoneVal = true;
                    if (_phone == "" || _phone == null) {
                        lblError.innerHTML = "Enter Phone";
                        phoneVal = false;
                    } else {
                        addressVal = true;
                        if (_address == "" || _address == null) {
                            _lblError.innerHTML = "Enter your Address";
                            addressVal = false;
                        } else {
                            addressVal = true;
                            if (emVal == true && fnVal == true && lnVal == true && phoneVal == true && addressVal == true) {
                                postIt();
                            }

                        }
                    }
                }

            }


        }
    } else {
        _lblError.innerHTML = "Enter Email ID";
        emVal = false;
   ...