diff --git a/airlock/templates/file_browser/index.html b/airlock/templates/file_browser/index.html
index 99abe8a8..ab118c22 100644
--- a/airlock/templates/file_browser/index.html
+++ b/airlock/templates/file_browser/index.html
@@ -39,4 +39,5 @@
   <script type="text/javascript" src="{% static 'htmx-1.9.10.min.js' %}"></script>
   {% django_htmx_script %}
   <script src="{% static 'assets/file_browser/index.js' %}"></script>
+  {% vite_asset "assets/src/scripts/resizer.js" %}
 {% endblock %}
diff --git a/assets/src/scripts/resizer.js b/assets/src/scripts/resizer.js
new file mode 100644
index 00000000..a4ef7349
--- /dev/null
+++ b/assets/src/scripts/resizer.js
@@ -0,0 +1,81 @@
+// Magic number for resizing
+const MAGIC_PIXELS = 8;
+
+/**
+ * Debounce a function to slow down how frequently it runs.
+ *
+ * @param {number} ms - Time to wait before running the function
+ * @param {function} fn - Function to run when being debounced
+ * @returns {function}
+ */
+function debouncer(ms, fn) {
+  let timer;
+  return (...args) => {
+    clearTimeout(timer);
+    timer = setTimeout(fn.bind(fn, args), ms);
+  };
+}
+
+/**
+ * Set the content height for either iframes, or workspace/request content,
+ * so that it fills the available space.
+ */
+function setContentHeight() {
+  const iframe = document.querySelector("iframe");
+  if (iframe) {
+    const iframeTop = iframe.getBoundingClientRect().top;
+    iframe.style.height = `${window.innerHeight - iframeTop - MAGIC_PIXELS}px`;
+  }
+
+  const selectedContent = document.getElementById("selected-contents");
+  if (selectedContent) {
+    const contentTop = selectedContent.getBoundingClientRect().top;
+    selectedContent.style.height = `${window.innerHeight - contentTop - MAGIC_PIXELS}px`;
+    selectedContent.classList.add("overflow-auto");
+  }
+}
+
+/**
+ * Set the height of the tree container to fill the available space.
+ */
+function setTreeHeight() {
+  const iframe = document.getElementById("tree-container");
+  if (iframe) {
+    const iframeTop = iframe.getBoundingClientRect().top;
+    iframe.style.height = `${window.innerHeight - iframeTop - MAGIC_PIXELS}px`;
+  }
+}
+
+/**
+ * On page load, add and remove the relevant styling classes, so that the
+ * content can fill the page.
+ */
+document.documentElement.classList.remove("min-h-screen");
+document.documentElement.classList.add("h-screen");
+
+document.body.classList.remove("min-h-screen");
+document.body.classList.add("h-screen");
+
+document.querySelector("main")?.classList.add("overflow-hidden");
+
+/**
+ * On browser resize, change the height of the content and file tree.
+ *
+ * Use the debouncer function to make sure this only runs when a user stops
+ * dragging the window size.
+ */
+const ro = new ResizeObserver(
+  debouncer(100, () => {
+    setContentHeight();
+    setTreeHeight();
+  }),
+);
+
+ro.observe(document.documentElement);
+
+/**
+ * When the user selects a file from the tree, HTMX replaces the content.
+ * Listen for this change, and reset the content height after the file content
+ * has been loaded.
+ */
+document.body.addEventListener("htmx:afterSettle", () => setContentHeight());
diff --git a/vite.config.js b/vite.config.js
index 96b2d6bb..ec1e4957 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -8,6 +8,7 @@ export default defineConfig({
     rollupOptions: {
       input: {
         main: "assets/src/scripts/main.js",
+        resizer: "assets/src/scripts/resizer.js",
       },
     },
   },