diff --git a/index.html b/index.html
new file mode 100644
index 0000000..52e968e
--- /dev/null
+++ b/index.html
@@ -0,0 +1,607 @@
+<html>
+<head>
+<title>Subnet Calculator</title>
+<script language="javascript" type="text/javascript">
+<!--
+
+var visibleColumns = {
+  subnet: true,
+  netmask: false,
+  range: true,
+  useable: true,
+  hosts: true,
+  divide: true,
+  join: true,
+};
+
+var curNetwork = 0;
+var curMask = 0;
+
+function updateNetwork()
+{
+  var newNetworkStr = document.forms['calc'].elements['network'].value;
+  var newMask = parseInt(document.forms['calc'].elements['netbits'].value);
+
+  var newNetwork = inet_aton(newNetworkStr);
+
+  if (newNetwork === null) {
+    alert('Invalid network address entered');
+    return;
+  }
+
+  var tmpNetwork = network_address(newNetwork, newMask);
+  if (newNetwork != tmpNetwork) {
+    alert('The network address entered is not on a network boundary for this mask.\nIt has been changed to '+inet_ntoa(tmpNetwork)+'.');
+    newNetwork = tmpNetwork;
+    document.forms['calc'].elements['network'].value = inet_ntoa(tmpNetwork);
+  }
+
+  if (newMask < 0 || newMask > 32) {
+    alert('The network mask you have entered is invalid');
+    return;
+  }
+
+  if (curMask == 0) {
+    curMask = newMask;
+    curNetwork = newNetwork;
+    startOver();
+  }
+  else if (curMask != newMask && confirm('You are changing the base network from /'+curMask+' to /'+newMask+'. This will reset any changes you have made. Proceed?')) {
+    curMask = newMask;
+    curNetwork = newNetwork;
+
+    startOver();
+  }
+  else {
+    document.forms['calc'].elements['netbits'].value = curMask;
+    curNetwork = newNetwork;
+
+    recreateTables();
+  }
+}
+
+function startOver()
+{
+  rootSubnet = [0, 0, null];
+
+  recreateTables();
+}
+
+function recreateTables()
+{
+  // Update header visibility
+  for (const name in visibleColumns) {
+    console.log(name)
+    document.getElementById(name + 'Header').style.display = visibleColumns[name] ? 'table-cell' : 'none';
+  }
+
+  var calcbody = document.getElementById('calcbody');
+  if (!calcbody) {
+    alert('Body not found');
+    return;
+  }
+
+  while (calcbody.hasChildNodes()) {
+    calcbody.removeChild(calcbody.firstChild);
+  }
+
+  updateNumChildren(rootSubnet);
+  updateDepthChildren(rootSubnet);
+
+  createRow(calcbody, rootSubnet, curNetwork, curMask, [curMask, rootSubnet[1], rootSubnet], rootSubnet[0]);
+
+  document.getElementById('joinHeader').colSpan = (rootSubnet[0] > 0 ? rootSubnet[0] : 1);
+//  document.getElementById('col_join').span = (rootSubnet[0] > 0 ? rootSubnet[0] : 1);
+
+  /* Create the bookmark hyperlink */
+  var link = document.getElementById('saveLink');
+  if (link) {
+    link.href = 'subnets.html?network='+inet_ntoa(curNetwork)+'&mask='+curMask+'&division='+binToAscii(nodeToString(rootSubnet));
+  }
+}
+
+function nodeToString(node)
+{
+  if (node[2]) {
+    return '1'+nodeToString(node[2][0])+nodeToString(node[2][1]);
+  }
+  else {
+    return '0';
+  }
+}
+
+function binToAscii(str)
+{
+  var curOut = '';
+  var curBit = 0;
+  var curChar = 0;
+
+  for (var i=0; i<str.length; i++) {
+    if (str.charAt(i) == '1') {
+      curChar |= 1<<curBit;
+    }
+    curBit++;
+    if (curBit > 3) {
+      curOut += curChar.toString(16);
+      curChar = 0;
+      curBit = 0;
+    }
+  }
+  if (curBit > 0) {
+    curOut += curChar.toString(16);
+  }
+  return str.length+'.'+curOut;
+}
+
+function asciiToBin(str)
+{
+  var re = /([0-9]+)\.([0-9a-f]+)/;
+  var res = re.exec(str);
+  var len = res[1];
+  var encoded = res[2];
+  var out = '';
+  for (var i=0; i< res[1]; i++) {
+    var ch = parseInt(res[2].charAt(Math.floor(i/4)), 16);
+    var pos = i % 4;
+    out += (ch & (1<<pos) ? '1' : '0');
+  }
+  return out;
+}
+
+function createRow(calcbody, node, address, mask, labels, depth)
+{
+  if (node[2]) {
+    var newlabels = labels;
+    newlabels.push(mask+1);
+    newlabels.push(node[2][0][1]);
+    newlabels.push(node[2][0]);
+    createRow(calcbody, node[2][0], address, mask+1, newlabels, depth-1);
+
+    newlabels = new Array();
+    newlabels.push(mask+1);
+    newlabels.push(node[2][1][1]);
+    newlabels.push(node[2][1]);
+    createRow(calcbody, node[2][1], address+subnet_addresses(mask+1), mask+1, newlabels, depth-1);
+  }
+  else {
+    var newRow = document.createElement('TR');
+    calcbody.appendChild(newRow);
+
+    /* subnet address */
+    if (visibleColumns.subnet) {
+      var newCell = document.createElement('TD');
+      newCell.appendChild(document.createTextNode(inet_ntoa(address)+'/'+mask));
+      newRow.appendChild(newCell);
+    }
+
+    var addressFirst = address;
+    var addressLast = subnet_last_address(address, mask);
+    var useableFirst = address + 1;
+    var useableLast = addressLast - 1;
+    var numHosts;
+    var addressRange;
+    var usaebleRange;
+
+    if (mask == 32) {
+      addressRange = inet_ntoa(addressFirst);
+      useableRange = addressRange;
+      numHosts = 1;
+    }
+    else {
+      addressRange = inet_ntoa(addressFirst)+' - '+inet_ntoa(addressLast);
+      if (mask == 31) {
+	useableRange = addressRange;
+	numHosts = 2;
+      }
+      else {
+	useableRange = inet_ntoa(useableFirst)+' - '+inet_ntoa(useableLast);
+	numHosts = (1 + useableLast - useableFirst);
+      }
+    }
+
+    /* netmask */
+    if (visibleColumns.netmask) {
+      var newCell = document.createElement('TD');
+      newCell.appendChild(document.createTextNode(inet_ntoa(subnet_netmask(mask))));
+      newRow.appendChild(newCell);
+    }
+
+    /* range of addresses */
+    if (visibleColumns.range) {
+      var newCell = document.createElement('TD');
+      newCell.appendChild(document.createTextNode(addressRange));
+      newRow.appendChild(newCell);
+    }
+
+    /* useable addresses */
+    if (visibleColumns.useable) {
+      var newCell = document.createElement('TD');
+      newCell.appendChild(document.createTextNode(useableRange));
+      newRow.appendChild(newCell);
+    }
+
+    /* Hosts */
+    if (visibleColumns.hosts) {
+      var newCell = document.createElement('TD');
+      newCell.appendChild(document.createTextNode(numHosts));
+      newRow.appendChild(newCell);
+    }
+
+    /* actions */
+
+    if (visibleColumns.divide) {
+      var newCell = document.createElement('TD');
+      newRow.appendChild(newCell);
+
+      if (mask == 32) {
+	var newLink = document.createElement('SPAN');
+	newLink.className = 'disabledAction';
+	newLink.appendChild(document.createTextNode('Divide'));
+	newCell.appendChild(newLink);
+      }
+      else {
+	var newLink = document.createElement('A');
+	newLink.href = '#';
+	newLink.onclick = function () { divide(node); return false; }
+	newLink.appendChild(document.createTextNode('Divide'));
+	newCell.appendChild(newLink);
+      }
+    }
+
+    if (visibleColumns.join) {
+      var colspan = depth - node[0];
+
+      for (var i=(labels.length/3)-1; i>=0; i--) {
+	var mask = labels[i*3];
+	var rowspan = labels[(i*3)+1];
+	var joinnode = labels[(i*3)+2];
+
+	var newCell = document.createElement('TD');
+	newCell.rowSpan = (rowspan > 1 ? rowspan : 1);
+	newCell.colSpan = (colspan > 1 ? colspan : 1);
+
+	if (i == (labels.length/3)-1) {
+	  newCell.className = 'maskSpan';
+	}
+	else {
+	  newCell.className = 'maskSpanJoinable';
+	  newCell.onclick = newJoin(joinnode);
+	  //	newCell.onmouseover = function() { window.status = joinnode[0]+'---'+joinnode[1]+'---'+joinnode[2]+'>>>>>'+node[2];}
+	}
+
+	var newImg = document.createElement('IMG');
+	newImg.src = 'img/'+mask+'.gif';
+	newCell.appendChild(newImg);
+	newRow.appendChild(newCell);
+
+	colspan = 1; // reset for subsequent cells
+      }
+    }
+  }
+
+}
+
+/* This is necessary because 'joinnode' changes during the scope of the caller */
+function newJoin(joinnode)
+{
+  return function() { join(joinnode) };
+}
+
+function divide(node)
+{
+  node[2] = new Array();
+  node[2][0] = [0, 0, null];
+  node[2][1] = [0, 0, null];
+  recreateTables();
+}
+
+function join(node)
+{
+  /* easy as pie */
+  node[2] = null;
+  recreateTables();
+}
+
+function updateNumChildren(node)
+{
+  if (node[2] == null) {
+    node[1] = 0;
+    return 1;
+  }
+  else {
+    node[1] = updateNumChildren(node[2][0]) + updateNumChildren(node[2][1]);
+    return node[1];
+  }
+}
+
+function updateDepthChildren(node)
+{
+  if (node[2] == null) {
+    node[0] = 0;
+    return 1;
+  }
+  else {
+    node[0] = updateDepthChildren(node[2][0]) + updateDepthChildren(node[2][1]);
+    return node[1];
+  }
+}
+
+
+var rootSubnet;
+
+// each node is Array:
+// [0] => depth of children, total number of visible children, children
+
+
+function inet_ntoa(addrint)
+{
+  return ((addrint >> 24) & 0xff)+'.'+
+    ((addrint >> 16) & 0xff)+'.'+
+    ((addrint >> 8) & 0xff)+'.'+
+    (addrint & 0xff);
+}
+
+function inet_aton(addrstr)
+{
+  var re = /^([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})$/;
+  var res = re.exec(addrstr);
+
+  if (res === null) {
+    return null;
+  }
+
+  for (var i=1; i<=4; i++) {
+    if (res[i] < 0 || res[i] > 255) {
+      return null;
+    }
+  }
+
+  return (res[1] << 24) | (res[2] << 16) | (res[3] << 8) | res[4];
+}
+
+function network_address(ip, mask)
+{
+  var maskbits = 0;
+  for (var i=31-mask; i>=0; i--) {
+    ip &= ~ 1<<i;
+  }
+  return ip;
+}
+
+function subnet_addresses(mask)
+{
+  return 2**(32-mask);
+}
+
+function subnet_last_address(subnet, mask)
+{
+  return subnet + subnet_addresses(mask) - 1;
+}
+
+function subnet_netmask(mask)
+{
+  return network_address(0xffffffff, mask);
+}
+
+
+function preloadSubnetImages()
+{
+  if (document.images) {
+    if (!document.preloadedImages) {
+      document.preloadedImages = new Array();
+    }
+
+    for (var i=0; i<=32; i++) {
+      var img = new Image();
+      img.src = 'img/'+i+'.gif';
+      document.preloadedImages.push(img);
+    }
+  }
+}
+
+
+function calcOnLoad()
+{
+  preloadSubnetImages();
+  args = parseQueryString();
+  if (args['network'] && args['mask'] && args['division']) {
+    document.forms['calc'].elements['network'].value = args['network'];
+    document.forms['calc'].elements['netbits'].value = args['mask'];
+    updateNetwork();
+    var division = asciiToBin(args['division']);
+    rootSubnet = [0, 0, null];
+    if (division != '0') {
+      loadNode(rootSubnet, division);
+    }
+    recreateTables();
+  }
+  else {
+    updateNetwork();
+  }
+}
+
+function loadNode(curNode, division)
+{
+  if (division.charAt(0) == '0') {
+    return division.substr(1);
+  }
+  else {
+    curNode[2] = new Array();
+    curNode[2][0] = [0, 0, null];
+    curNode[2][1] = [0, 0, null];
+
+    division = loadNode(curNode[2][0], division.substr(1));
+    division = loadNode(curNode[2][1], division);
+    return division;
+  }
+}
+
+
+function parseQueryString (str)
+{
+  str = str ? str : location.search;
+  var query = str.charAt(0) == '?' ? str.substring(1) : str;
+  var args = new Object();
+  if (query) {
+    var fields = query.split('&');
+    for (var f = 0; f < fields.length; f++) {
+      var field = fields[f].split('=');
+      args[unescape(field[0].replace(/\+/g, ' '))] = 
+	unescape(field[1].replace(/\+/g, ' '));
+    }
+  }
+  return args;
+}
+
+window.onload = calcOnLoad;
+
+function toggleColumn(cb)
+{
+  var colName = 'col_'+(cb.id.substr(3));
+//  var col = document.getElementById(colName);
+
+  visibleColumns[cb.id.substr(3)] = cb.checked;
+
+//  if (cb.checked) {
+//    col.style.display = 'table-column';
+//    col.style.visibility = 'visible';
+//  }
+//  else {
+//    col.style.display = 'none';
+//    col.style.visibility = 'collapse';
+//  }
+  recreateTables(); /* because IE draws lines all over the place with border-collapse */
+}
+
+//-->
+</script>
+<link rel="icon" type="image/png" href="https://nibblecdn.com/logo/nibblegap.svg">
+<link rel="stylesheet" href="https://nibblecdn.com/css/dark.css" type="text/css" media="screen">
+<style type="text/css">
+
+H1		{
+ font-family: IBM Plex Mono,monospace;
+  font-size: 18pt;
+}
+
+P		{
+  font-family: IBM Plex Mono,monospace;
+  font-size: 75%;
+}
+
+.label {
+ font-family: IBM Plex Mono,monospace;
+  font-size: 60%;
+}
+  
+input, select, textarea {
+  border: 1px solid #ccc;
+}
+
+.calc {
+ font-family: IBM Plex Mono,monospace;
+  font-size: 80%;
+  border-collapse: collapse; 
+}
+
+.calc td, .calc th {
+border: 1px solid #d9534f;
+}
+
+.calc thead {
+  font-weight: bold;
+  background-color: #1D1F21;
+}
+
+.disabledAction {
+ color: #dddddd;
+}
+
+.maskSpan {
+  background-color: #fff;
+  text-align: right;
+}
+.maskSpanJoinable {
+  background-color: #fff;
+  text-align: right;
+ cursor: pointer;
+}
+
+.maskSpanRotate {
+ filter:progid:DXImageTransform.Microsoft.BasicImage(rotation=1);
+ background-color:green;
+}
+
+</style>
+</head>
+<body>
+<div class="page-header">
+                    <h1 class="title"><img style="vertical-align:middle" src="https://nibblecdn.com/logo/nibblegap.svg" alt="Subnet Calculator" width="30" height="30"> <a style="vertical-align:middle"> Subnet Calculator</a></h1></div>
+<table width="100%">
+<tr valign=top>
+<td>
+
+
+<p>Enter the network you wish to subnet:</p>
+
+<form name="calc" onsubmit="updateNetwork(); return false;">
+
+<table cellspacing="0">
+<tr>
+<td class="label">Network Address</td>
+<td class="label">Mask bits</td>
+</tr>
+<tr>
+<td><input type="text" name="network" size="15" maxlength="15" value="192.168.0.0"></td>
+<td>/<input type="text" name="netbits" size="2" maxlength="2" value="16"></td>
+<td><input class="btn btn-link" type="submit" value="Update">
+<input class="btn btn-link" type="button" value="Reset" onclick="if (confirm('This will reset all subnet divisions you have made. Proceed?')) startOver();">
+</td>
+</tr>
+</table>
+
+<p>Show columns: 
+<input type="checkbox" id="cb_subnet" checked onclick="toggleColumn(this)"><label for="cb_subnet">Subnet address</label>
+<input type="checkbox" id="cb_netmask" onclick="toggleColumn(this)"><label for="cb_netmask">Netmask</label>
+<input type="checkbox" id="cb_range" checked onclick="toggleColumn(this)"><label for="cb_range">Range of addresses</label>
+<input type="checkbox" id="cb_useable" checked onclick="toggleColumn(this)"><label for="cb_useable">Useable IPs</label>
+<input type="checkbox" id="cb_hosts" checked onclick="toggleColumn(this)"><label for="cb_hosts">Hosts</label>
+<input type="checkbox" id="cb_divide" checked onclick="toggleColumn(this)"><label for="cb_divide">Divide</label>
+<input type="checkbox" id="cb_join" checked onclick="toggleColumn(this)"><label for="cb_join">Join</label>
+</p>
+</form>
+<p>Click below to split and join subnets.<br>
+If you wish to save this subnetting for later, bookmark <a href="subnets.html" id="saveLink">this hyperlink</a>.</p>
+</td>
+</tr>
+</table>
+<br>
+<table class="calc" cellspacing="0" cellpadding="2">
+<thead>
+<tr>
+<th id="subnetHeader">Subnet address</th>
+<th id="netmaskHeader">Netmask</th>
+<th id="rangeHeader">Range of addresses</th>
+<th id="useableHeader">Useable IPs</th>
+<th id="hostsHeader">Hosts</th>
+<th id="divideHeader">Divide</th>
+<th id="joinHeader">Join</th>
+</tr>
+</thead>
+<tbody id="calcbody">
+<!--tr>
+<td>130.94.203.0/24</td>
+<td>130.94.203.0 - 130.94.203.255</td>
+<td>130.94.203.1 - 130.94.203.254 (254)</td>
+<td>Divide</td>
+</tr-->
+</tbody>
+</table>
+<br><br>
+<hr noshade color="#D5D8D7" size="1">
+<br><br>
+<div class="footer">
+<center><small><a href="https://nibbleorg.com" target="_blank">NibbleOrg</a> | <a href="https://nibbletools.com" target="_blank">other tools</a></small></center>
+</div>
+</body>
+</html>
