diff --git a/app/assets/images/caret-down.svg b/app/assets/images/caret-down.svg
new file mode 100644
index 000000000..a19d0f357
--- /dev/null
+++ b/app/assets/images/caret-down.svg
@@ -0,0 +1 @@
+<svg width="24" height="24" fill="none" xmlns="http://www.w3.org/2000/svg"><path d="M4 8l8 8 8-8" stroke="#000" stroke-width="4" stroke-linecap="round" stroke-linejoin="round"/></svg>
\ No newline at end of file
diff --git a/app/assets/stylesheets/base.css b/app/assets/stylesheets/base.css
index 526b502bc..9301bbc61 100644
--- a/app/assets/stylesheets/base.css
+++ b/app/assets/stylesheets/base.css
@@ -21,6 +21,7 @@
     background: var(--color-bg);
     color: var(--color-ink);
     font-family: var(--font-sans);
+    interpolate-size: allow-keywords;
     line-height: 1.375;
     overflow: unset;
     scroll-behavior: auto;
diff --git a/app/assets/stylesheets/buttons.css b/app/assets/stylesheets/buttons.css
index 3b6b3ebcc..0ca763506 100644
--- a/app/assets/stylesheets/buttons.css
+++ b/app/assets/stylesheets/buttons.css
@@ -193,3 +193,4 @@
     }
   }
 }
+
diff --git a/app/assets/stylesheets/cards.css b/app/assets/stylesheets/cards.css
index 366fdb6e3..d16a96e56 100644
--- a/app/assets/stylesheets/cards.css
+++ b/app/assets/stylesheets/cards.css
@@ -121,7 +121,7 @@
     position: relative;
     z-index: 0;
 
-    &:has(dialog[open]) {
+    &:has([open]) {
       z-index: 1;
     }
 
diff --git a/app/assets/stylesheets/expander.css b/app/assets/stylesheets/expander.css
new file mode 100644
index 000000000..e7be6c769
--- /dev/null
+++ b/app/assets/stylesheets/expander.css
@@ -0,0 +1,112 @@
+/* https://nerdy.dev/open-and-close-transitions-for-the-details-element */
+
+.expander {
+  --expander-height: calc(1em + 1lh);
+  --expander-width: 11ch;
+  --expander-radius: calc(var(--expander-height) / 2);
+  --expander-duration: 150ms;
+
+  interpolate-size: allow-keywords;
+  position: relative;
+  z-index: 1;
+}
+
+.expander__button {
+  --btn-border-radius: var(--expander-radius);
+
+  align-items: center;
+  block-size: var(--expander-height);
+  cursor: pointer;
+  display: flex;
+  inline-size: var(--expander-width);
+  justify-content: flex-start;
+  padding-inline: 1.5ch;
+  position: relative;
+  white-space: nowrap;
+  z-index: 1;
+
+  &::-webkit-details-marker {
+    display: none;
+  }
+
+  [open] & {
+    box-shadow: none;
+  }
+
+  .icon {
+    font-size: 1ch;
+  }
+}
+
+.expander__content {
+  --btn-border-radius: var(--expander-radius);
+
+  align-items: stretch;
+  border-radius: var(--expander-radius);
+  flex-direction: column;
+  gap: 0;
+  padding-block-start: var(--expander-height);
+
+  &:hover {
+    box-shadow: none;
+  }
+}
+
+/* For browsers that support animation */
+@supports selector(details::details-content) {
+  .expander::details-content {
+    --btn-border-radius: var(--expander-radius);
+
+    block-size: var(--expander-height);
+    border-radius: var(--expander-radius);
+    inset: 0 auto auto 0;
+    inline-size: var(--expander-width);
+    overflow: clip;
+    position: absolute;
+    transition: content-visibility var(--expander-duration) allow-discrete, block-size var(--expander-duration), inline-size var(--expander-duration);
+  }
+
+  .expander[open]::details-content {
+    block-size: auto;
+    inline-size: auto;
+  }
+
+  .expander__content {
+    min-inline-size: var(--expander-width);
+  }
+}
+
+/* Fallback for browsers that don't support animation */
+@supports not selector(details::details-content) {
+  .expander__content {
+    border-radius: var(--expander-radius);
+    inset: 0 auto auto 0;
+    min-inline-size: var(--expander-width);
+    position: absolute;
+
+    [open] & {
+      block-size: auto;
+      inline-size: auto;
+    }
+  }
+}
+
+.expander__item {
+  --btn-background: transparent;
+  --btn-border-radius: 0.3em;
+  --btn-border-size: 0;
+  --btn-font-weight: 500;
+  --btn-padding: var(--inline-space-half) var(--inline-space);
+  --hover-size: 0;
+  --outline-color: transparent;
+
+  inline-size: calc(100% + var(--inline-space-double));
+  margin-inline-start: calc(-1 * var(--inline-space));
+  justify-content: flex-start;
+  white-space: nowrap;
+
+  &:hover,
+  &:focus-visible {
+    background-color: oklch(var(--lch-white) / 15%);
+  }
+}
diff --git a/app/assets/stylesheets/icons.css b/app/assets/stylesheets/icons.css
index 10e273bb5..2f0989518 100644
--- a/app/assets/stylesheets/icons.css
+++ b/app/assets/stylesheets/icons.css
@@ -35,6 +35,7 @@
   .icon--calendar-add { --svg: url("calendar-add.svg "); }
   .icon--calendar { --svg: url("calendar.svg "); }
   .icon--camera { --svg: url("camera.svg "); }
+  .icon--caret-down { --svg: url("caret-down.svg "); }
   .icon--chart { --svg: url("chart.svg "); }
   .icon--check { --svg: url("check.svg "); }
   .icon--close { --svg: url("close.svg "); }
diff --git a/app/javascript/controllers/details_controller.js b/app/javascript/controllers/details_controller.js
new file mode 100644
index 000000000..7259fd665
--- /dev/null
+++ b/app/javascript/controllers/details_controller.js
@@ -0,0 +1,13 @@
+import { Controller } from "@hotwired/stimulus"
+
+export default class extends Controller {
+  static targets = [ "details" ]
+
+  close() {
+    this.detailsTarget.removeAttribute("open")
+  }
+
+  closeOnClickOutside({ target }) {
+    if (!this.element.contains(target)) this.close()
+  }
+}
diff --git a/app/javascript/controllers/expandable_controller.js b/app/javascript/controllers/expandable_controller.js
deleted file mode 100644
index 74b3bc050..000000000
--- a/app/javascript/controllers/expandable_controller.js
+++ /dev/null
@@ -1,9 +0,0 @@
-import { Controller } from "@hotwired/stimulus"
-
-export default class extends Controller {
-  closeOnFocusOutside(event) {
-    if (!this.element.contains(event.relatedTarget)) {
-      this.element.removeAttribute("open")
-    }
-  }
-}
diff --git a/app/views/cards/_closure_toggle.html.erb b/app/views/cards/_closure_toggle.html.erb
index 46cf6e6ff..6ad45c388 100644
--- a/app/views/cards/_closure_toggle.html.erb
+++ b/app/views/cards/_closure_toggle.html.erb
@@ -5,23 +5,19 @@
       <span>Un-do</span>
     <% end %>
   <% else %>
-    <div class="flex-inline center position-relative" data-controller="dialog" data-action="keydown.esc->dialog#close click@document->dialog#closeOnClickOutside">
-      <button class="btn borderless" data-action="click->dialog#open:stop">
-        <span>Close as…</span>
-      </button>
-
-      <dialog class="popup panel flex-column align-start gap-half fill-white shadow" style="--row-gap: 0.2em;"
-          aria-label="Close as…" aria-description="Close this card and select a reason.."
-          data-dialog-target="dialog" data-action="turbo:before-cache@document->dialog#close">
-        <strong class="popup__title margin-block-start-half pad-inline-half">Close as…</strong>
-
+    <details class="expander" data-controller="details" data-details-target="details" data-action="keydown.esc->details#close click@document->details#closeOnClickOutside">
+      <summary class="expander__button btn borderless">
+        Close as
+        <%= icon_tag "caret-down" %>
+      </summary>
+      <div class="expander__content btn borderless">
         <% Current.account.closure_reasons.labels.each do |label| %>
-          <%= button_to card_closure_path(card, reason: label), class: "btn popup__item full-width", form_class: "full-width" do %>
+          <%= button_to card_closure_path(card, reason: label), class: "expander__item btn" do %>
             <span class="overflow-ellipsis"><%= label %></span>
           <% end %>
         <% end %>
-      </dialog>
-    </div>
+      </div>
+    </details>
 
     <span class="card__closure-message">
       <% if card.doing? %>