diff --git a/index.html b/index.html
index a911e2d..77f747a 100644
--- a/index.html
+++ b/index.html
@@ -25,12 +25,15 @@
   <div data-section="View" data-alt="v">
     <div data-section="Test" data-alt="e">
       <div data-section="Test" data-alt="e">
-        <button disabled>-</button>
+        <button disabled>1</button>
       </div>
+      <button disabled>2</button>
+      <button>102983019283012</button>
     </div>
+    <button disabled>3</button>
   </div>
 </nav>
-<nav id="left-menu" data-state="planning">
+<aside id="left-menu" data-state="planning">
   <span data-resize="left-menu"></span>
   <section id="block-picker">
     <label>
@@ -43,7 +46,7 @@
       </template>
     </div>
   </section>
-</nav>
+</aside>
 <main>
   <div data-state="initialization">
     Select configuration file:
@@ -62,11 +65,11 @@
     </div>
   </div>
 </main>
-<nav id="right-menu">
+<aside id="right-menu">
   <span data-resize="right-menu"></span>
-</nav>
-<nav id="bottom-menu">
+</aside>
+<footer id="bottom-menu">
   <span data-resize="bottom-menu"></span>
-</nav>
+</footer>
 </body>
 </html>
diff --git a/scripts/menu-bar.js b/scripts/menu-bar.js
index 7a3128b..dc59be1 100644
--- a/scripts/menu-bar.js
+++ b/scripts/menu-bar.js
@@ -1 +1,108 @@
-export function initializeMenuBar() {}
+import { positionAsTooltip } from "./tooltip.js";
+
+let activeMenuBar = null;
+
+export function initializeMenuBar() {
+  document.querySelectorAll(".menu-bar").forEach(menuBar => {
+    menuBar.querySelectorAll("button").forEach(button => {
+      button.setAttribute("tabindex", "-1");
+      button.replaceChildren(createAltSpan(button, button.innerText));
+      button.addEventListener("click", e => {
+        menuBar.classList.remove("active");
+        menuBar.querySelectorAll(".active")
+            .forEach(elem => elem.classList.remove("active"));
+        activeMenuBar = null;
+      });
+      button.addEventListener("mouseenter", () => {
+        if (!activeMenuBar) return;
+
+        button.parentElement.querySelectorAll(".active")
+            .forEach(elem => elem.classList.remove("active"));
+      });
+    });
+    menuBar.querySelectorAll("[data-section]").forEach(section => {
+      const button = document.createElement("button");
+      button.setAttribute("tabindex", "-1");
+      button.dataset.forSection = "";
+      button.appendChild(createAltSpan(section, section.dataset.section));
+      section.parentElement.insertBefore(button, section);
+
+      section.addEventListener("click", e => e.stopPropagation());
+      button.addEventListener("click", e => e.stopPropagation());
+
+      function updateActive() {
+        if (!activeMenuBar) return;
+
+        button.parentElement.querySelectorAll(".active")
+            .forEach(elem => elem.classList.remove("active"));
+        button.classList.add("active");
+        section.classList.add("active");
+        positionAsTooltip(button, section, {
+          horizontal: section.parentElement === menuBar ? "left" : "right",
+          vertical: section.parentElement === menuBar ? "bottom" : "top",
+        });
+      }
+
+      if (section.parentElement === menuBar) {
+        button.addEventListener("click", () => {
+          if (section.classList.contains("active")) {
+            menuBar.classList.remove("active");
+            menuBar.querySelectorAll(".active")
+                .forEach(elem => elem.classList.remove("active"));
+            activeMenuBar = null;
+          } else {
+            menuBar.querySelectorAll(".active")
+                .forEach(elem => elem.classList.remove("active"));
+            menuBar.classList.add("active");
+            section.classList.add("active");
+            window.addEventListener("click", handleGlobalClick);
+            activeMenuBar = menuBar;
+            updateActive();
+          }
+        });
+      }
+      button.addEventListener("mouseenter", updateActive);
+    });
+  });
+
+  // TODO: keyboard navigation with alt and arrow keys
+}
+
+
+function handleGlobalClick() {
+  console.log("Global clicked");
+  if (!activeMenuBar) return;
+  activeMenuBar.classList.remove("active");
+  activeMenuBar.querySelectorAll(".active")
+      .forEach(section => section.classList.remove("active"));
+  activeMenuBar = null;
+  window.removeEventListener("click", handleGlobalClick);
+}
+
+function createAltSpan(element, text) {
+  const altKey = element.dataset.alt;
+
+  if (!altKey) {
+    const span = document.createElement("span");
+    span.appendChild(document.createTextNode(text));
+    return span;
+  }
+
+  const [ , before, key, after ] = new RegExp(`^(.*)(${altKey})(.*)$`, "i").exec(text);
+  const span = document.createElement("span");
+
+  if (before) {
+    span.appendChild(document.createTextNode(before));
+  }
+
+  const underlineSpan = document.createElement("span");
+  underlineSpan.innerText = key;
+  underlineSpan.classList.add("alt-key");
+  span.appendChild(underlineSpan);
+
+  if (after) {
+    span.appendChild(document.createTextNode(after));
+  }
+
+  return span;
+}
diff --git a/scripts/tooltip.js b/scripts/tooltip.js
index eefa824..fd2c112 100644
--- a/scripts/tooltip.js
+++ b/scripts/tooltip.js
@@ -49,6 +49,14 @@ export function deleteTooltip(id) {
   delete tooltips[id];
 }
 
+export function positionAsTooltip(mainElement, tooltipElement, { horizontal = "left", vertical = "bottom" } = {}) {
+  const targetRect = mainElement.getBoundingClientRect();
+  const domRect = tooltipElement.getBoundingClientRect();
+  const windowWidth = window.innerWidth, windowHeight = window.innerHeight;
+  tooltipElement.style.left = `${Math.min(targetRect[horizontal], windowWidth - domRect.width)}px`;
+  tooltipElement.style.top = `${Math.min(targetRect[vertical], windowHeight - domRect.height)}px`;
+}
+
 function showTooltip() {
   if (suppressTooltips) return;
   if (!lastCoordinates) return;
@@ -66,11 +74,7 @@ function showTooltip() {
   dom.style.top = `${targetRect.bottom}px`;
 
   target.appendChild(dom);
-
-  const domRect = dom.getBoundingClientRect();
-  const windowWidth = window.innerWidth, windowHeight = window.innerHeight;
-  dom.style.left = `${Math.min(targetRect.left, windowWidth - domRect.width)}px`;
-  dom.style.top = `${Math.min(targetRect.bottom, windowHeight - domRect.height)}px`;
+  positionAsTooltip(target, dom);
 
   activeTooltipTarget = target;
 }
diff --git a/style.css b/style.css
index ada788d..147985e 100644
--- a/style.css
+++ b/style.css
@@ -14,6 +14,7 @@
     --default-size: 16px;
 
     --dark-bg: #990099;
+    --dark-bg-text: #fffe;
     --menu-border-color: #666;
     --resize-handle-color: #666;
     --resize-handle-width: 3px;
@@ -45,7 +46,7 @@
 body {
     display: grid;
     grid-template-columns: var(--left-menu-size, 15%) 1fr var(--right-menu-size, 10%);
-    grid-template-rows: 28px 1fr var(--bottom-menu-size, 15%);
+    grid-template-rows: min-content 1fr var(--bottom-menu-size, 15%);
     height: 100%;
     margin: 0;
 }
@@ -54,6 +55,7 @@ body {
     grid-row: 1;
 
     background-color: var(--dark-bg);
+    color: var(--dark-bg-text);
 }
 #left-menu {
     grid-column: 1;
@@ -229,3 +231,46 @@ input:not([type="checkbox"]):not([type="radio"]):not([type="file"]) {
     border: var(--tooltip-border-size, 1px) solid var(--tooltip-border-color, #fff);
     /*max-width: var(--tooltip-width, 200px);*/
 }
+
+.menu-bar {
+    user-select: none;
+    cursor: default;
+}
+.menu-bar > [data-section] {
+    display: inline;
+}
+.menu-bar [data-section]:not(.active) {
+    display: none;
+}
+.menu-bar [data-section] {
+    position: fixed;
+    background: var(--menu-bg, #222);
+    color: var(--menu-fg, #fffe);
+    display: flex;
+    flex-direction: column;
+    z-index: 100;
+    box-shadow: var(--menu-shadow, 0 2px 4px rgba(0, 0, 0, 0.2));
+}
+.menu-bar button {
+    all: initial;
+    font: inherit;
+    color: inherit;
+    padding: var(--menu-item-padding, 0.25em);
+    font-size: var(--menu-item-font-size, 0.8em);
+    cursor: default;
+}
+.menu-bar button:disabled {
+    color: var(--menu-item-disabled-color, #aaae);
+}
+.menu-bar [data-section] button.active, .menu-bar [data-section] button:hover:not(:disabled) {
+    background: var(--menu-bg-hover, #444);
+    color: var(--menu-fg-hover, #fffe);
+}
+.menu-bar [data-section] button[data-for-section]::after {
+    content: '>';
+    float: right;
+    margin-left: 0.5em;
+}
+.menu-bar .alt-key {
+    text-decoration: underline;
+}