diff --git a/css/editor.css b/css/editor.css
index f9b5ecb..d376623 100644
--- a/css/editor.css
+++ b/css/editor.css
@@ -23,7 +23,6 @@ body {
   appearance: none;
   border: none;
   outline: none;
-  resize: none;
   max-width: 100%;
   min-width: 15%;
   color: var(--input-number);
@@ -34,7 +33,7 @@ body {
   justify-content: center;
   background: var(--history-accent-2);
   height: 100%;
-  /* cursor: ew-resize; */
+  cursor: ew-resize;
 }
 
 .output {
diff --git a/html/index.html b/html/index.html
index 00286ba..f8f6de9 100644
--- a/html/index.html
+++ b/html/index.html
@@ -28,7 +28,7 @@ <h1 class="no-show">
           contenteditable="plaintext-only"
           spellcheck="false"
         ></div>
-        <div class="separator"></div>
+        <div id="separator" class="separator"></div>
         <div
           id="output"
           class="output"
diff --git a/js/editor.js b/js/editor.js
index 95d24a3..c16ded5 100644
--- a/js/editor.js
+++ b/js/editor.js
@@ -21,6 +21,12 @@ let homeCurrency;
 let showHelp = false;
 let evaluatedValues = []; // All evaluated expressions by line
 let docId;
+let calculator;
+let separators;
+let startX;
+let editorWidthBefore;
+let outputWidthBefore;
+
 document.addEventListener("DOMContentLoaded", init);
 
 export async function setupHomeCurrency() {
@@ -262,6 +268,7 @@ function createHistoryElements() {
 
     const separatorElement = document.createElement("div");
     separatorElement.className = "separator";
+    separatorElement.id = "separator";
 
     historyItemsElement.appendChild(historyItemEditor);
     historyItemsElement.appendChild(separatorElement);
@@ -369,6 +376,12 @@ function setupListeners() {
   helpOverlayTables.addEventListener("click", onOverlayClick, false);
   var calculatorHistory = document.getElementById("calculator-history");
   calculatorHistory.addEventListener("click", onHistoryClick, false);
+  window.addEventListener("resize", onWindowResize, false);
+  separators = document.body.querySelectorAll("#separator");
+  calculator = document.getElementById("calculator");
+  separators.forEach(function (separator) {
+    separator.addEventListener("mousedown", updateWidthOnResize, false);
+  });
 }
 
 async function onEditorInput() {
@@ -675,6 +688,51 @@ async function copyValueToClipboard(value) {
   }
 }
 
+function onWindowResize(e) {
+  // update with default values on window resize
+  updateWidthOfCalculator("1fr", "minmax(150px, 37%)");
+  updateWidthOfHistory("1fr", "minmax(150px, 37%)");
+}
+
+function updateWidthOnResize(e) {
+  startX = e.clientX;
+  const gridStyles = window.getComputedStyle(calculator);
+  const existingGridWidths = gridStyles
+    .getPropertyValue("grid-template-columns")
+    .split(" ");
+  editorWidthBefore = parseFloat(existingGridWidths[0]);
+  outputWidthBefore = parseFloat(existingGridWidths[2]);
+
+  document.addEventListener("mousemove", resize);
+  document.addEventListener("mouseup", stopResize);
+}
+
+async function updateWidthOfHistory(editorWidth, outputWidth) {
+  let historyItemsList = document.body.querySelectorAll("#history-items");
+  if (!_.isEmpty(historyItemsList)) {
+    historyItemsList.forEach((item) => {
+      item.style.gridTemplateColumns = `${editorWidth} 5px ${outputWidth}`;
+    });
+  }
+}
+
+function updateWidthOfCalculator(editorWidth, outputWidth) {
+  calculator.style.gridTemplateColumns = `${editorWidth} 5px ${outputWidth}`;
+}
+
+function resize(e) {
+  const dx = e.clientX - startX;
+  const editorWidthAfter = `${editorWidthBefore + dx}px`;
+  const outputWidthAfter = `${outputWidthBefore - dx}px`;
+  updateWidthOfCalculator(editorWidthAfter, outputWidthAfter);
+  updateWidthOfHistory(editorWidthAfter, outputWidthAfter);
+}
+
+function stopResize() {
+  document.removeEventListener("mousemove", resize);
+  document.removeEventListener("mouseup", stopResize);
+}
+
 export async function initSentry() {
   Sentry.init({
     dsn: "https://f6181e1f6794abaf08674441d2c08403@o4507406315159552.ingest.de.sentry.io/4507406320992336",