diff --git a/index.html b/index.html
index 2a5e9214..214bfa9e 100644
--- a/index.html
+++ b/index.html
@@ -2951,14 +2951,15 @@
           </select>
         </div>
         <div id="templateTools">
-          <button id="templateHill" data-tip="Hill: small blob" class="noicon">H</button>
-          <button id="templatePit" data-tip="Pit: round depression" class="noicon">P</button>
-          <button id="templateRange" data-tip="Range: elongated elevation" class="noicon">R</button>
-          <button id="templateTrough" data-tip="Trough: elongated depression" class="noicon">T</button>
-          <button id="templateStrait" data-tip="Strait: centered vertical or horizontal depression" class="noicon">S</button>
-          <button id="templateAdd" data-tip="Add or subtract value from all heights in range" class="noicon">+</button>
-          <button id="templateMultiply" data-tip="Multiply all heights in range by factor" class="noicon">*</button>
-          <button id="templateSmooth" data-tip="Smooth the map replacing cell heights by an average values of its neighbors" class="noicon">~</button>
+          <button data-type="Hill" data-tip="Hill: small blob" class="noicon">H</button>
+          <button data-type="Pit" data-tip="Pit: round depression" class="noicon">P</button>
+          <button data-type="Range" data-tip="Range: elongated elevation" class="noicon">R</button>
+          <button data-type="Trough" data-tip="Trough: elongated depression" class="noicon">T</button>
+          <button data-type="Strait" data-tip="Strait: centered vertical or horizontal depression" class="noicon">S</button>
+          <button data-type="Insulate" data-tip="Insulate: lower cells near edges" class="noicon">I</button>
+          <button data-type="Add" data-tip="Add or subtract value from all heights in range" class="noicon">+</button>
+          <button data-type="Multiply" data-tip="Multiply all heights in range by factor" class="noicon">*</button>
+          <button data-type="Smooth" data-tip="Smooth the map replacing cell heights by an average values of its neighbors" class="noicon">~</button>
         </div>
         <div id="templateBody" data-changed="0" class="table" style="padding: 2px 0">
           <div data-type="Hill">
@@ -6110,7 +6111,7 @@
 
     <script src="modules/voronoi.js"></script>
     <script src="modules/heightmap-templates.js"></script>
-    <script src="modules/heightmap-generator.js"></script>
+    <script src="modules/heightmap-generator.js?v=21052020"></script>
     <script src="modules/ocean-layers.js"></script>
     <script src="modules/river-generator.js"></script>
     <script src="modules/lakes.js"></script>
@@ -6140,7 +6141,7 @@
     <script defer src="modules/ui/editors.js?v=18052022"></script>
     <script defer src="modules/ui/tools.js"></script>
     <script defer src="modules/ui/world-configurator.js"></script>
-    <script defer src="modules/ui/heightmap-editor.js"></script>
+    <script defer src="modules/ui/heightmap-editor.js?v=21052020"></script>
     <script defer src="modules/ui/provinces-editor.js?v=19052022"></script>
     <script defer src="modules/ui/biomes-editor.js?v=18052022"></script>
     <script defer src="modules/ui/namesbase-editor.js"></script>
diff --git a/modules/heightmap-generator.js b/modules/heightmap-generator.js
index 0723a34a..0f77e770 100644
--- a/modules/heightmap-generator.js
+++ b/modules/heightmap-generator.js
@@ -26,7 +26,7 @@ window.HeightmapGenerator = (function () {
         // load heightmap into image and render to canvas
         const img = new Image();
         img.src = `./heightmaps/${input.value}.png`;
-        img.onload = function () {
+        img.onload = () => {
           ctx.drawImage(img, 0, 0, cellsX, cellsY);
           const imageData = ctx.getImageData(0, 0, cellsX, cellsY);
           assignColorsToHeight(imageData.data);
@@ -61,6 +61,7 @@ window.HeightmapGenerator = (function () {
     if (a1 === "Range") return addRange(a2, a3, a4, a5);
     if (a1 === "Trough") return addTrough(a2, a3, a4, a5);
     if (a1 === "Strait") return addStrait(a2, a3);
+    if (a1 === "Insulate") return insulate(a2);
     if (a1 === "Add") return modify(a3, +a2, 1);
     if (a1 === "Multiply") return modify(a3, 0, +a2);
     if (a1 === "Smooth") return smooth(a2);
@@ -100,7 +101,7 @@ window.HeightmapGenerator = (function () {
     if (cells === 100000) return 0.93;
   }
 
-  const addHill = function (count, height, rangeX, rangeY) {
+  const addHill = (count, height, rangeX, rangeY) => {
     count = getNumberInRange(count);
     const power = getBlobPower();
     while (count > 0) {
@@ -137,7 +138,7 @@ window.HeightmapGenerator = (function () {
     }
   };
 
-  const addPit = function (count, height, rangeX, rangeY) {
+  const addPit = (count, height, rangeX, rangeY) => {
     count = getNumberInRange(count);
     while (count > 0) {
       addOnePit();
@@ -173,7 +174,7 @@ window.HeightmapGenerator = (function () {
     }
   };
 
-  const addRange = function (count, height, rangeX, rangeY) {
+  const addRange = (count, height, rangeX, rangeY) => {
     count = getNumberInRange(count);
     const power = getLinePower();
     while (count > 0) {
@@ -259,7 +260,7 @@ window.HeightmapGenerator = (function () {
     }
   };
 
-  const addTrough = function (count, height, rangeX, rangeY) {
+  const addTrough = (count, height, rangeX, rangeY) => {
     count = getNumberInRange(count);
     const power = getLinePower();
     while (count > 0) {
@@ -354,7 +355,7 @@ window.HeightmapGenerator = (function () {
     }
   };
 
-  const addStrait = function (width, direction = "vertical") {
+  const addStrait = (width, direction = "vertical") => {
     width = Math.min(getNumberInRange(width), grid.cellsX / 3);
     if (width < 1 && P(width)) return;
     const used = new Uint8Array(cells.h.length);
@@ -407,7 +408,7 @@ window.HeightmapGenerator = (function () {
     }
   };
 
-  const modify = function (range, add, mult, power) {
+  const modify = (range, add, mult, power) => {
     const min = range === "land" ? 20 : range === "all" ? 0 : +range.split("-")[0];
     const max = range === "land" || range === "all" ? 100 : +range.split("-")[1];
     const isLand = min === 20;
@@ -422,14 +423,26 @@ window.HeightmapGenerator = (function () {
     });
   };
 
-  const smooth = function (fr = 2, add = 0) {
+  const smooth = (fr = 2, add = 0) => {
     cells.h = cells.h.map((h, i) => {
       const a = [h];
       cells.c[i].forEach(c => a.push(cells.h[c]));
+      if (fr === 1) return d3.mean(a) + add;
       return lim((h * (fr - 1) + d3.mean(a) + add) / fr);
     });
   };
 
+  const insulate = (fr = 2) => {
+    const power = fr * 2;
+    cells.h = cells.h.map((h, i) => {
+      const [x, y] = p[i];
+      const nx = (2 * x) / graphWidth - 1;
+      const ny = (2 * y) / graphHeight - 1;
+      const distance = (1 - nx ** power) * (1 - ny ** power); // 1 is center, 0 is edge
+      return h * distance;
+    });
+  };
+
   function getPointInRange(range, length) {
     if (typeof range !== "string") {
       ERROR && console.error("Range should be a string");
@@ -449,5 +462,5 @@ window.HeightmapGenerator = (function () {
     }
   }
 
-  return {generate, addHill, addRange, addTrough, addStrait, addPit, smooth, modify};
+  return {generate, addHill, addRange, addTrough, addStrait, addPit, smooth, modify, insulate};
 })();
diff --git a/modules/heightmap-templates.js b/modules/heightmap-templates.js
index bd371e10..0266ce39 100644
--- a/modules/heightmap-templates.js
+++ b/modules/heightmap-templates.js
@@ -119,7 +119,6 @@ window.HeightmapTemplates = (function () {
     Hill 3-4 60-85 20-80 0-5
     Hill 3-4 60-85 20-80 95-100`;
 
-
   const oldWorld = `Hill 4-6 20-40 15-85 30-45
     Hill 3-7 20-40 15-85 55-70
     Strait 2-7 vertical 0 0
@@ -170,5 +169,20 @@ window.HeightmapTemplates = (function () {
     Strait 3-7 vertical 0 0
     Trough 1-2 40-50 45-65 45-65`;
 
-  return {volcano, highIsland, lowIsland, continents, archipelago, atoll, mediterranean, peninsula, peninsula, pangea, isthmus, shattered, taklamakan, oldWorld};
+  return {
+    volcano,
+    highIsland,
+    lowIsland,
+    continents,
+    archipelago,
+    atoll,
+    mediterranean,
+    peninsula,
+    peninsula,
+    pangea,
+    isthmus,
+    shattered,
+    taklamakan,
+    oldWorld
+  };
 })();
diff --git a/modules/ui/heightmap-editor.js b/modules/ui/heightmap-editor.js
index fae944f3..8e11965b 100644
--- a/modules/ui/heightmap-editor.js
+++ b/modules/ui/heightmap-editor.js
@@ -34,19 +34,19 @@ function editHeightmap() {
   modules.editHeightmap = true;
 
   // add listeners
-  document.getElementById("paintBrushes").addEventListener("click", openBrushesPanel);
-  document.getElementById("applyTemplate").addEventListener("click", openTemplateEditor);
-  document.getElementById("convertImage").addEventListener("click", openImageConverter);
-  document.getElementById("heightmapPreview").addEventListener("click", toggleHeightmapPreview);
-  document.getElementById("heightmap3DView").addEventListener("click", changeViewMode);
-  document.getElementById("finalizeHeightmap").addEventListener("click", finalizeHeightmap);
-  document.getElementById("renderOcean").addEventListener("click", mockHeightmap);
-  document.getElementById("templateUndo").addEventListener("click", () => restoreHistory(edits.n - 1));
-  document.getElementById("templateRedo").addEventListener("click", () => restoreHistory(edits.n + 1));
+  byId("paintBrushes").on("click", openBrushesPanel);
+  byId("applyTemplate").on("click", openTemplateEditor);
+  byId("convertImage").on("click", openImageConverter);
+  byId("heightmapPreview").on("click", toggleHeightmapPreview);
+  byId("heightmap3DView").on("click", changeViewMode);
+  byId("finalizeHeightmap").on("click", finalizeHeightmap);
+  byId("renderOcean").on("click", mockHeightmap);
+  byId("templateUndo").on("click", () => restoreHistory(edits.n - 1));
+  byId("templateRedo").on("click", () => restoreHistory(edits.n + 1));
 
   function enterHeightmapEditMode(type) {
     editHeightmap.layers = Array.from(mapLayers.querySelectorAll("li:not(.buttonoff)")).map(node => node.id); // store layers preset
-    editHeightmap.layers.forEach(l => document.getElementById(l).click()); // turn off all layers
+    editHeightmap.layers.forEach(l => byId(l).click()); // turn off all layers
 
     customization = 1;
     closeDialogs();
@@ -113,7 +113,7 @@ function editHeightmap() {
     if (tooltip.dataset.main) showMainTip();
 
     // move radius circle if drag mode is active
-    const pressed = document.getElementById("brushesButtons").querySelector("button.pressed");
+    const pressed = byId("brushesButtons").querySelector("button.pressed");
     if (!pressed) return;
     moveCircle(p[0], p[1], brushRadius.valueAsNumber, "#333");
   }
@@ -137,7 +137,7 @@ function editHeightmap() {
   function finalizeHeightmap() {
     if (viewbox.select("#heights").selectAll("*").size() < 200)
       return tip("Insufficient land area! There should be at least 200 land cells to finalize the heightmap", null, "error");
-    if (document.getElementById("imageConverter").offsetParent) return tip("Please exit the Image Conversion mode first", null, "error");
+    if (byId("imageConverter").offsetParent) return tip("Please exit the Image Conversion mode first", null, "error");
 
     delete window.edits; // remove global variable
     redo.disabled = templateRedo.disabled = true;
@@ -145,7 +145,7 @@ function editHeightmap() {
 
     customization = 0;
     customizationMenu.style.display = "none";
-    if (document.getElementById("options").querySelector(".tab > button.active").id === "toolsTab") toolsContent.style.display = "block";
+    if (byId("options").querySelector(".tab > button.active").id === "toolsTab") toolsContent.style.display = "block";
     layersPreset.disabled = false;
     exitCustomization.style.display = "none"; // hide finalize button
     restoreDefaultEvents();
@@ -153,8 +153,8 @@ function editHeightmap() {
     closeDialogs();
     resetZoom();
 
-    if (document.getElementById("preview")) document.getElementById("preview").remove();
-    if (document.getElementById("canvas3d")) enterStandardView();
+    if (byId("preview")) byId("preview").remove();
+    if (byId("canvas3d")) enterStandardView();
 
     const mode = heightmapEditMode.innerHTML;
     if (mode === "erase") regenerateErasedData();
@@ -163,7 +163,7 @@ function editHeightmap() {
 
     // restore initial layers
     //viewbox.select("#heights").remove();
-    document.getElementById("heights").remove();
+    byId("heights").remove();
     turnButtonOff("toggleHeight");
     document
       .getElementById("mapLayers")
@@ -501,8 +501,8 @@ function editHeightmap() {
     redo.disabled = templateRedo.disabled = true;
     if (!noStat) {
       updateStatistics();
-      if (document.getElementById("preview")) drawHeightmapPreview(); // update heightmap preview if opened
-      if (document.getElementById("canvas3d")) ThreeD.redraw(); // update 3d heightmap preview if opened
+      if (byId("preview")) drawHeightmapPreview(); // update heightmap preview if opened
+      if (byId("canvas3d")) ThreeD.redraw(); // update 3d heightmap preview if opened
     }
   }
 
@@ -516,8 +516,8 @@ function editHeightmap() {
     mockHeightmap();
     updateStatistics();
 
-    if (document.getElementById("preview")) drawHeightmapPreview(); // update heightmap preview if opened
-    if (document.getElementById("canvas3d")) ThreeD.redraw(); // update 3d heightmap preview if opened
+    if (byId("preview")) drawHeightmapPreview(); // update heightmap preview if opened
+    if (byId("canvas3d")) ThreeD.redraw(); // update 3d heightmap preview if opened
   }
 
   // restart edits from 1st step
@@ -543,31 +543,31 @@ function editHeightmap() {
     modules.openBrushesPanel = true;
 
     // add listeners
-    document.getElementById("brushesButtons").addEventListener("click", e => toggleBrushMode(e));
-    document.getElementById("changeOnlyLand").addEventListener("click", e => changeOnlyLandClick(e));
-    document.getElementById("undo").addEventListener("click", () => restoreHistory(edits.n - 1));
-    document.getElementById("redo").addEventListener("click", () => restoreHistory(edits.n + 1));
-    document.getElementById("rescaleShow").addEventListener("click", () => {
-      document.getElementById("modifyButtons").style.display = "none";
-      document.getElementById("rescaleSection").style.display = "block";
+    byId("brushesButtons").on("click", e => toggleBrushMode(e));
+    byId("changeOnlyLand").on("click", e => changeOnlyLandClick(e));
+    byId("undo").on("click", () => restoreHistory(edits.n - 1));
+    byId("redo").on("click", () => restoreHistory(edits.n + 1));
+    byId("rescaleShow").on("click", () => {
+      byId("modifyButtons").style.display = "none";
+      byId("rescaleSection").style.display = "block";
     });
-    document.getElementById("rescaleHide").addEventListener("click", () => {
-      document.getElementById("modifyButtons").style.display = "block";
-      document.getElementById("rescaleSection").style.display = "none";
+    byId("rescaleHide").on("click", () => {
+      byId("modifyButtons").style.display = "block";
+      byId("rescaleSection").style.display = "none";
     });
-    document.getElementById("rescaler").addEventListener("change", e => rescale(e.target.valueAsNumber));
-    document.getElementById("rescaleCondShow").addEventListener("click", () => {
-      document.getElementById("modifyButtons").style.display = "none";
-      document.getElementById("rescaleCondSection").style.display = "block";
+    byId("rescaler").on("change", e => rescale(e.target.valueAsNumber));
+    byId("rescaleCondShow").on("click", () => {
+      byId("modifyButtons").style.display = "none";
+      byId("rescaleCondSection").style.display = "block";
     });
-    document.getElementById("rescaleCondHide").addEventListener("click", () => {
-      document.getElementById("modifyButtons").style.display = "block";
-      document.getElementById("rescaleCondSection").style.display = "none";
+    byId("rescaleCondHide").on("click", () => {
+      byId("modifyButtons").style.display = "block";
+      byId("rescaleCondSection").style.display = "none";
     });
-    document.getElementById("rescaleExecute").addEventListener("click", rescaleWithCondition);
-    document.getElementById("smoothHeights").addEventListener("click", smoothAllHeights);
-    document.getElementById("disruptHeights").addEventListener("click", disruptAllHeights);
-    document.getElementById("brushClear").addEventListener("click", startFromScratch);
+    byId("rescaleExecute").on("click", rescaleWithCondition);
+    byId("smoothHeights").on("click", smoothAllHeights);
+    byId("disruptHeights").on("click", disruptAllHeights);
+    byId("brushClear").on("click", startFromScratch);
 
     function exitBrushMode() {
       const pressed = document.querySelector("#brushesButtons > button.pressed");
@@ -576,7 +576,7 @@ function editHeightmap() {
 
       viewbox.style("cursor", "default").on(".drag", null);
       removeCircle();
-      document.getElementById("brushesSliders").style.display = "none";
+      byId("brushesSliders").style.display = "none";
     }
 
     const dragBrushThrottled = throttle(dragBrush, 100);
@@ -586,7 +586,7 @@ function editHeightmap() {
         return;
       }
       exitBrushMode();
-      document.getElementById("brushesSliders").style.display = "block";
+      byId("brushesSliders").style.display = "block";
       e.target.classList.add("pressed");
       viewbox.style("cursor", "crosshair").call(d3.drag().on("start", dragBrushThrottled));
     }
@@ -644,21 +644,15 @@ function editHeightmap() {
       const land = changeOnlyLand.checked;
       grid.cells.h = grid.cells.h.map(h => (land && (h < 20 || h + v < 20) ? h : lim(h + v)));
       updateHeightmap();
-      document.getElementById("rescaler").value = 0;
+      byId("rescaler").value = 0;
     }
 
     function rescaleWithCondition() {
       const range = rescaleLower.value + "-" + rescaleHigher.value;
       const operator = conditionSign.value;
       const operand = rescaleModifier.valueAsNumber;
-      if (Number.isNaN(operand)) {
-        tip("Operand should be a number", false, "error");
-        return;
-      }
-      if ((operator === "add" || operator === "subtract") && !Number.isInteger(operand)) {
-        tip("Operand should be an integer", false, "error");
-        return;
-      }
+      if (Number.isNaN(operand)) return tip("Operand should be a number", false, "error");
+      if ((operator === "add" || operator === "subtract") && !Number.isInteger(operand)) return tip("Operand should be an integer", false, "error");
 
       if (operator === "multiply") HeightmapGenerator.modify(range, 0, operand, 0);
       else if (operator === "divide") HeightmapGenerator.modify(range, 0, 1 / operand, 0);
@@ -697,7 +691,7 @@ function editHeightmap() {
 
   function openTemplateEditor() {
     if ($("#templateEditor").is(":visible")) return;
-    const body = document.getElementById("templateBody");
+    const body = byId("templateBody");
 
     $("#templateEditor").dialog({
       title: "Template Editor",
@@ -713,7 +707,7 @@ function editHeightmap() {
     $("#templateBody").sortable({items: "> div", handle: ".icon-resize-vertical", containment: "#templateBody", axis: "y"});
 
     // add listeners
-    body.addEventListener("click", function (ev) {
+    body.on("click", function (ev) {
       const el = ev.target;
       if (el.classList.contains("icon-check")) {
         el.classList.remove("icon-check");
@@ -734,27 +728,27 @@ function editHeightmap() {
       }
     });
 
-    document.getElementById("templateTools").addEventListener("click", e => addStepOnClick(e));
-    document.getElementById("templateSelect").addEventListener("change", e => selectTemplate(e));
-    document.getElementById("templateRun").addEventListener("click", executeTemplate);
-    document.getElementById("templateSave").addEventListener("click", downloadTemplate);
-    document.getElementById("templateLoad").addEventListener("click", () => templateToLoad.click());
-    document.getElementById("templateToLoad").addEventListener("change", function () {
+    byId("templateTools").on("click", addStepOnClick);
+    byId("templateSelect").on("change", selectTemplate);
+    byId("templateRun").on("click", executeTemplate);
+    byId("templateSave").on("click", downloadTemplate);
+    byId("templateLoad").on("click", () => templateToLoad.click());
+    byId("templateToLoad").on("change", function () {
       uploadFile(this, uploadTemplate);
     });
 
     function addStepOnClick(e) {
       if (e.target.tagName !== "BUTTON") return;
-      const type = e.target.id.replace("template", "");
-      document.getElementById("templateBody").dataset.changed = 1;
+      const type = e.target.dataset.type;
+      byId("templateBody").dataset.changed = 1;
       addStep(type);
     }
 
     function addStep(type, count, dist, arg4, arg5) {
-      const body = document.getElementById("templateBody");
+      const body = byId("templateBody");
       body.insertAdjacentHTML("beforeend", getStepHTML(type, count, dist, arg4, arg5));
       const elDist = body.querySelector("div:last-child").querySelector(".templateDist");
-      if (elDist) elDist.addEventListener("change", setRange);
+      if (elDist) elDist.on("change", setRange);
       if (dist && elDist && elDist.tagName === "SELECT") {
         for (const o of elDist.options) {
           if (o.value === dist) elDist.value = dist;
@@ -769,36 +763,56 @@ function editHeightmap() {
     }
 
     function getStepHTML(type, count, arg3, arg4, arg5) {
-      const Trash = `<i class="icon-trash-empty pointer" data-tip="Click to remove the step"></i>`;
-      const Hide = `<div class="icon-check" data-tip="Click to skip the step"></div>`;
-      const Reorder = `<i class="icon-resize-vertical" data-tip="Drag to reorder"></i>`;
-      const common = `<div data-type="${type}">${Hide}<div style="width:4em">${type}</div>${Trash}${Reorder}`;
+      const Trash = /* html */ `<i class="icon-trash-empty pointer" data-tip="Click to remove the step"></i>`;
+      const Hide = /* html */ `<div class="icon-check" data-tip="Click to skip the step"></div>`;
+      const Reorder = /* html */ `<i class="icon-resize-vertical" data-tip="Drag to reorder"></i>`;
+      const common = /* html */ `<div data-type="${type}">${Hide}<div style="width:4em">${type}</div>${Trash}${Reorder}`;
 
-      const TempY = `<span>y:<input class="templateY" data-tip="Placement range percentage along Y axis (minY-maxY)" value=${arg5 || "20-80"}></span>`;
-      const TempX = `<span>x:<input class="templateX" data-tip="Placement range percentage along X axis (minX-maxX)" value=${arg4 || "15-85"}></span>`;
-      const Height = `<span>h:<input class="templateHeight" data-tip="Blob maximum height, use hyphen to get a random number in range" value=${
-        arg3 || "40-50"
-      }></span>`;
-      const Count = `<span>n:<input class="templateCount" data-tip="Blobs to add, use hyphen to get a random number in range" value=${count || "1-2"}></span>`;
-      const blob = `${common}${TempY}${TempX}${Height}${Count}</div>`;
+      const TempY = /* html */ `<span>y:<input class="templateY" data-tip="Placement range percentage along Y axis (minY-maxY)"
+        value=${arg5 || "20-80"}></span>`;
+
+      const TempX = /* html */ `<span>x:<input class="templateX" data-tip="Placement range percentage along X axis (minX-maxX)"
+        value=${arg4 || "15-85"}></span>`;
+
+      const Height = /* html */ `<span>h:<input class="templateHeight" data-tip="Blob maximum height, use hyphen to get a random number in range"
+        value=${arg3 || "40-50"}></span>`;
+
+      const Count = /* html */ `<span>n:<input class="templateCount" data-tip="Blobs to add, use hyphen to get a random number in range"
+        value=${count || "1-2"}></span>`;
+
+      if (type === "Hill" || type === "Pit" || type === "Range" || type === "Trough") return /* html */ `${common}${TempY}${TempX}${Height}${Count}</div>`;
 
-      if (type === "Hill" || type === "Pit" || type === "Range" || type === "Trough") return blob;
       if (type === "Strait")
-        return `${common}<span>d:<select class="templateDist" data-tip="Strait direction"><option value="vertical" selected>vertical</option><option value="horizontal">horizontal</option></select></span><span>w:<input class="templateCount" data-tip="Strait width, use hyphen to get a random number in range" value=${
-          count || "2-7"
-        }></span></div>`;
+        return /* html */ `${common}<span>d:<select class="templateDist" data-tip="Strait direction">
+            <option value="vertical" selected>vertical</option>
+            <option value="horizontal">horizontal</option>
+          </select></span>
+          <span>w:<input class="templateCount" data-tip="Strait width, use hyphen to get a random number in range" value=${count || "2-7"}></span></div>`;
+
+      if (type === "Insulate")
+        return /* html */ `${common}<span>f:<input class="templateCount" data-tip="Set insulation power. 1 - full insulation, 2 - half-insulation, etc." type="number" min=1 max=10
+          value=${count || 2}></span></div>`;
+
       if (type === "Add")
-        return `${common}<span>to:<select class="templateDist" data-tip="Change only land or all cells"><option value="all" selected>all cells</option><option value="land">land only</option><option value="interval">interval</option></select></span><span>v:<input class="templateCount" data-tip="Add value to height of all cells (negative values are allowed)" type="number" value=${
-          count || -10
-        } min=-100 max=100 step=1></span></div>`;
+        return /* html */ `${common}<span>to:<select class="templateDist" data-tip="Change only land or all cells">
+            <option value="all" selected>all cells</option>
+            <option value="land">land only</option>
+            <option value="interval">interval</option>
+          </select></span>
+          <span>v:<input class="templateCount" data-tip="Add value to height of all cells (negative values are allowed)"
+            type="number" value=${count || -10} min=-100 max=100 step=1></span></div>`;
+
       if (type === "Multiply")
-        return `${common}<span>to:<select class="templateDist" data-tip="Change only land or all cells"><option value="all" selected>all cells</option><option value="land">land only</option><option value="interval">interval</option></select></span><span>v:<input class="templateCount" data-tip="Multiply all cells Height by the value" type="number" value=${
-          count || 1.1
-        } min=0 max=10 step=.1></span></div>`;
+        return /* html */ `${common}<span>to:<select class="templateDist" data-tip="Change only land or all cells">
+            <option value="all" selected>all cells</option>
+            <option value="land">land only</option><option value="interval">interval</option>
+          </select></span>
+          <span>v:<input class="templateCount" data-tip="Multiply all cells Height by the value" type="number"
+          value=${count || 1.1} min=0 max=10 step=.1></span></div>`;
+
       if (type === "Smooth")
-        return `${common}<span>f:<input class="templateCount" data-tip="Set smooth fraction. 1 - full smooth, 2 - half-smooth, etc." type="number" min=1 max=10 value=${
-          count || 2
-        }></span></div>`;
+        return /* html */ `${common}<span>f:<input class="templateCount" data-tip="Set smooth fraction. 1 - full smooth, 2 - half-smooth, etc." type="number" min=1 max=10
+          value=${count || 2}></span></div>`;
     }
 
     function setRange(event) {
@@ -813,7 +827,7 @@ function editHeightmap() {
     }
 
     function selectTemplate(e) {
-      const body = document.getElementById("templateBody");
+      const body = byId("templateBody");
       const steps = body.querySelectorAll("div").length;
       const changed = +body.getAttribute("data-changed");
       const template = e.target.value;
@@ -839,7 +853,7 @@ function editHeightmap() {
     }
 
     function changeTemplate(template) {
-      const body = document.getElementById("templateBody");
+      const body = byId("templateBody");
       body.setAttribute("data-changed", 0);
       body.innerHTML = "";
 
@@ -856,11 +870,11 @@ function editHeightmap() {
     }
 
     function executeTemplate() {
-      const body = document.getElementById("templateBody");
+      const body = byId("templateBody");
       const steps = body.querySelectorAll("#templateBody > div");
       if (!steps.length) return;
 
-      const {addHill, addPit, addRange, addTrough, addStrait, modify, smooth} = HeightmapGenerator;
+      const {addHill, addPit, addRange, addTrough, addStrait, modify, smooth, insulate} = HeightmapGenerator;
       grid.cells.h = new Uint8Array(grid.cells.i.length); // clean all heights
 
       for (const step of steps) {
@@ -878,6 +892,7 @@ function editHeightmap() {
         else if (type === "Range") addRange(count, height, x, y);
         else if (type === "Trough") addTrough(count, height, x, y);
         else if (type === "Strait") addStrait(count, dist);
+        else if (type === "Insulate") insulate(+count);
         else if (type === "Add") modify(dist, +count, 1);
         else if (type === "Multiply") modify(dist, 0, +count);
         else if (type === "Smooth") smooth(+count);
@@ -887,12 +902,12 @@ function editHeightmap() {
 
       updateStatistics();
       mockHeightmap();
-      if (document.getElementById("preview")) drawHeightmapPreview(); // update heightmap preview if opened
-      if (document.getElementById("canvas3d")) ThreeD.redraw(); // update 3d heightmap preview if opened
+      if (byId("preview")) drawHeightmapPreview(); // update heightmap preview if opened
+      if (byId("canvas3d")) ThreeD.redraw(); // update 3d heightmap preview if opened
     }
 
     function downloadTemplate() {
-      const body = document.getElementById("templateBody");
+      const body = byId("templateBody");
       body.dataset.changed = 0;
       const steps = body.querySelectorAll("#templateBody > div");
       if (!steps.length) return;
@@ -977,18 +992,18 @@ function editHeightmap() {
     })();
 
     // add listeners
-    document.getElementById("convertImageLoad").addEventListener("click", () => imageToLoad.click());
-    document.getElementById("imageToLoad").addEventListener("change", loadImage);
-    document.getElementById("convertAutoLum").addEventListener("click", () => autoAssing("lum"));
-    document.getElementById("convertAutoHue").addEventListener("click", () => autoAssing("hue"));
-    document.getElementById("convertAutoFMG").addEventListener("click", () => autoAssing("scheme"));
-    document.getElementById("convertColorsButton").addEventListener("click", setConvertColorsNumber);
-    document.getElementById("convertComplete").addEventListener("click", applyConversion);
-    document.getElementById("convertCancel").addEventListener("click", cancelConversion);
-    document.getElementById("convertOverlay").addEventListener("input", function () {
+    byId("convertImageLoad").on("click", () => imageToLoad.click());
+    byId("imageToLoad").on("change", loadImage);
+    byId("convertAutoLum").on("click", () => autoAssing("lum"));
+    byId("convertAutoHue").on("click", () => autoAssing("hue"));
+    byId("convertAutoFMG").on("click", () => autoAssing("scheme"));
+    byId("convertColorsButton").on("click", setConvertColorsNumber);
+    byId("convertComplete").on("click", applyConversion);
+    byId("convertCancel").on("click", cancelConversion);
+    byId("convertOverlay").on("input", function () {
       setOverlayOpacity(this.value);
     });
-    document.getElementById("convertOverlayNumber").addEventListener("input", function () {
+    byId("convertOverlayNumber").on("input", function () {
       setOverlayOpacity(this.value);
     });
 
@@ -1012,7 +1027,7 @@ function editHeightmap() {
       document.body.appendChild(img);
 
       img.onload = function () {
-        const ctx = document.getElementById("canvas").getContext("2d");
+        const ctx = byId("canvas").getContext("2d");
         ctx.drawImage(img, 0, 0, graphWidth, graphHeight);
         heightsFromImage(+convertColors.value);
         resetZoom();
@@ -1023,7 +1038,7 @@ function editHeightmap() {
     }
 
     function heightsFromImage(count) {
-      const sourceImage = document.getElementById("canvas");
+      const sourceImage = byId("canvas");
       const sampleCanvas = document.createElement("canvas");
       sampleCanvas.width = grid.cellsX;
       sampleCanvas.height = grid.cellsY;
@@ -1062,7 +1077,7 @@ function editHeightmap() {
         .attr("class", "color-div")
         .on("click", colorClicked);
 
-      document.getElementById("colorsUnassignedNumber").innerHTML = colors.length;
+      byId("colorsUnassignedNumber").innerHTML = colors.length;
     }
 
     function mapClicked() {
@@ -1119,8 +1134,8 @@ function editHeightmap() {
         colorsAssigned.appendChild(selectedColor);
         colorsAssigned.style.display = "block";
 
-        document.getElementById("colorsUnassignedNumber").innerHTML = colorsUnassigned.childElementCount - 2;
-        document.getElementById("colorsAssignedNumber").innerHTML = colorsAssigned.childElementCount - 2;
+        byId("colorsUnassignedNumber").innerHTML = colorsUnassigned.childElementCount - 2;
+        byId("colorsAssignedNumber").innerHTML = colorsAssigned.childElementCount - 2;
       }
     }
 
@@ -1187,7 +1202,7 @@ function editHeightmap() {
 
       colorsAssigned.style.display = "block";
       colorsUnassigned.style.display = "none";
-      document.getElementById("colorsAssignedNumber").innerHTML = colorsAssigned.childElementCount - 2;
+      byId("colorsAssignedNumber").innerHTML = colorsAssigned.childElementCount - 2;
     }
 
     function setConvertColorsNumber() {
@@ -1203,7 +1218,7 @@ function editHeightmap() {
 
     function setOverlayOpacity(v) {
       convertOverlay.value = convertOverlayNumber.value = v;
-      document.getElementById("canvas").style.opacity = v;
+      byId("canvas").style.opacity = v;
     }
 
     function applyConversion() {
@@ -1230,10 +1245,10 @@ function editHeightmap() {
     }
 
     function restoreImageConverterState() {
-      const canvas = document.getElementById("canvas");
+      const canvas = byId("canvas");
       if (canvas) canvas.remove();
 
-      const image = document.getElementById("imageToConvert");
+      const image = byId("imageToConvert");
       if (image) image.remove();
 
       d3.select("#imageConverter").selectAll("div.color-div").remove();
@@ -1275,8 +1290,8 @@ function editHeightmap() {
   }
 
   function toggleHeightmapPreview() {
-    if (document.getElementById("preview")) {
-      document.getElementById("preview").remove();
+    if (byId("preview")) {
+      byId("preview").remove();
       return;
     }
     const preview = document.createElement("canvas");
@@ -1284,13 +1299,13 @@ function editHeightmap() {
     preview.width = grid.cellsX;
     preview.height = grid.cellsY;
     document.body.insertBefore(preview, optionsContainer);
-    preview.addEventListener("mouseover", () => tip("Heightmap preview. Click to download a screen-sized image"));
-    preview.addEventListener("click", downloadPreview);
+    preview.on("mouseover", () => tip("Heightmap preview. Click to download a screen-sized image"));
+    preview.on("click", downloadPreview);
     drawHeightmapPreview();
   }
 
   function drawHeightmapPreview() {
-    const ctx = document.getElementById("preview").getContext("2d");
+    const ctx = byId("preview").getContext("2d");
     const imageData = ctx.createImageData(grid.cellsX, grid.cellsY);
 
     grid.cells.h.forEach((height, i) => {
@@ -1306,7 +1321,7 @@ function editHeightmap() {
   }
 
   function downloadPreview() {
-    const preview = document.getElementById("preview");
+    const preview = byId("preview");
     const dataURL = preview.toDataURL("image/png");
 
     const img = new Image();