JSFiddle - React, Tailwind, and code Playground
HTML
<form method="POST" name="myform" onsubmit="return check_agree()">
<table class="mama_checkout">
<colgroup>
<col width="100">
<col width="250">
</colgroup>
<tbody><tr>
<td>Full Name:</td> <td><input type="text" name="name" value=""></td>
</tr><tr>
<td>Country of Residence:</td> <td><select name="country"><option value="AF">Afghanistan</option><option value="AX">Aland Islands</option><option value="AL">Albania</option><option value="DZ">Algeria</option><option value="AS">American Samoa</option><option value="AD">Andorra</option><option value="AO">Angola</option><option value="AI">Anguilla</option><option value="AQ">Antarctica</option><option value="AG">Antigua and Barbuda</option><option value="AR">Argentina</option><option value="AM">Armenia</option><option value="AW">Aruba</option><option value="AU">Australia</option><option value="AT">Austria</option><option value="AZ">Azerbaijan</option><option value="BS">Bahamas</option><option value="BH">Bahrain</option><option value="BD">Bangladesh</option><option value="BB">Barbados</option><option value="BY">Belarus</option><option value="BE">Belgium</option><option value="BZ">Belize</option><option value="BJ">Benin</option><option value="BM">Bermuda</option><option value="BT">Bhutan</option><option value="BO">Bolivia</option><option value="BA">Bosnia and Herzegovina</option><option value="BW">Botswana</option><option value="BV">Bouvet Island</option><option value="BR">Brazil</option><option value="IO">British Indian Ocean Territory</option><option value="BN">Brunei Darussalam</option><option value="BG">Bulgaria</option><option value="BF">Burkina Faso</option><option value="BI">Burundi</option><option value="KH">Cambodia</option><option value="CM">Cameroon</option><option value="CA">Canada</option><option value="CV">Cape Verde</option><option value="KY">Cayman islands</option><option value="CF">Central African Republic</option><option value="TD">Chad</option><option...
CSS
body {height: 400%; width: 100%; position: absolute;}
JavaScript
$(document).ready(function(){
//to lock
$('#lock').click(function(){
$('form').css('position','relative').prepend($('<div class="mask" style="position:absolute;z-index:9000;height:100%;width:100%;background-image:url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAadEVYdFNvZnR3YXJlAFBhaW50Lk5FVCB2My41LjEwMPRyoQAAAA1JREFUGFdj+P//PwMACPwC/ohfBuAAAAAASUVORK5CYII=);"></div>')).find('input,textarea,select').attr('tabindex','-1');
});
//to unlock:
$('#unlock').click(function(){
$('form *').removeAttr('tabindex').filter('.mask').remove();
});
});