diff --git a/public/tide-pool.css b/public/tide-pool.css
index 8c3b28e..844cd20 100644
--- a/public/tide-pool.css
+++ b/public/tide-pool.css
@@ -84,6 +84,11 @@ body:has(.tide-pool) .theme-toggle, body:has(.tide-pool) .theme-preferences { di
 .tide-inspect { position: absolute; z-index: 3; right: clamp(16px, 3.4vw, 56px); bottom: 150px; width: 244px; padding: .9rem 1rem 1rem; background: var(--panel); border: 1px solid var(--line); }
 .tide-inspect[hidden] { display: none; }
 .tide-inspect h2 { margin: .25rem 0 .7rem; font: 400 1.9rem/1 var(--site-font-display); letter-spacing: .02em; }
+/* A quiet cross in the corner, with a full-size touch target; the heading keeps clear of it. */
+.tide-inspect header { padding-right: 2rem; }
+#tide-inspect-close { position: absolute; top: 0; right: 0; width: 44px; height: 44px; padding: 0; color: var(--muted); background: none; border: 0; font-size: 1.15rem; line-height: 1; }
+#tide-inspect-close:hover { color: #e5e0e8; }
+#tide-inspect-close:focus-visible { outline-offset: -4px; }
 .tide-facts { display: grid; grid-template-columns: 1fr 1fr; gap: .55rem .8rem; margin: 0 0 .8rem; }
 .tide-facts dd { margin: .15rem 0 0; font-size: .82rem; font-variant-numeric: tabular-nums; }
 .tide-meter { height: 6px; background: #1e1c20; }
@@ -216,3 +221,7 @@ body:has(.tide-pool) .theme-toggle, body:has(.tide-pool) .theme-preferences { di
   .tide-log { display: none; }
   .tide-status { bottom: 84px; }
 }
+/* Short windows at mid widths: the sheet stays above the raised corner strips too, where there is room for it. */
+@media (max-height: 620px) and (min-height: 540px) and (max-width: 1080px) and (min-width: 721px) {
+  .tide-inspect { bottom: 136px; }
+}
diff --git a/public/tide-pool.js b/public/tide-pool.js
index ae4f668..d592f65 100644
--- a/public/tide-pool.js
+++ b/public/tide-pool.js
@@ -1809,7 +1809,10 @@ async function initialize() {
     if (following) { goal.x = c.x; goal.z = c.z; clampGoal(); }
     wake();
   });
-  $('#tide-release').addEventListener('click', () => { release(); status.textContent = 'Released. Tap any machine to follow it.'; canvas.focus(); });
+  // The close button in the sheet's corner lets go just as Release does.
+  root.querySelectorAll('#tide-release, #tide-inspect-close').forEach(b => b.addEventListener('click', () => {
+    release(); status.textContent = 'Released. Tap any machine to follow it.'; canvas.focus();
+  }));
 
   // A quiet ticker of notable events near the view.
   const ticker = $('#tide-ticker');
diff --git a/src/components/tide-pool.tsx b/src/components/tide-pool.tsx
index 70fde96..e44784b 100644
--- a/src/components/tide-pool.tsx
+++ b/src/components/tide-pool.tsx
@@ -82,6 +82,7 @@ export function TidePoolContent() {
         <header>
           <p class="tide-kicker" id="tide-inspect-kind">Specimen</p>
           <h2 id="tide-inspect-title">—</h2>
+          <button type="button" id="tide-inspect-close" aria-label="Close">×</button>
         </header>
         <dl class="tide-facts">
           <div><dt>Generation</dt><dd id="tide-gen">—</dd></div>
@@ -141,7 +142,7 @@ export function TidePoolContent() {
       </details>
       {/* Lets the three.js add-ons resolve the same pinned module the page already uses. */}
       <script type="importmap" dangerouslySetInnerHTML={{ __html: JSON.stringify({ imports: { three: "/public/tide-pool-vendor/three.module.js" } }) }}/>
-      <script type="module" src="/public/tide-pool.js?v=68"></script>
+      <script type="module" src="/public/tide-pool.js?v=69"></script>
     </main>
   );
 }
diff --git a/src/index.tsx b/src/index.tsx
index 964eee1..a67c991 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -187,7 +187,7 @@ app.get("/other", async (c) => {
 // Commissioned public artwork, listed under Other. Unlike the artifacts, it is indexable.
 app.get("/tide-pool", async (c) => {
   const stream = renderToReadableStream(
-    <Shell title="Tide pool" stylesheets={["/public/tide-pool.css?v=16"]}>
+    <Shell title="Tide pool" stylesheets={["/public/tide-pool.css?v=17"]}>
       <TidePool />
     </Shell>
   );
diff --git a/src/tide-pool.test.tsx b/src/tide-pool.test.tsx
index 534b066..6213438 100644
--- a/src/tide-pool.test.tsx
+++ b/src/tide-pool.test.tsx
@@ -20,6 +20,7 @@ test("public tide pool keeps the shell and progressive enhancement with an immer
   assert.ok(!html.includes("tide-still"));
   assert.ok(html.includes('id="tide-canvas" hidden'));
   assert.ok(html.includes('id="tide-sound" aria-pressed="false" disabled'));
+  assert.ok(html.split('id="tide-inspect"')[1].split("</section>")[0].includes('<button type="button" id="tide-inspect-close" aria-label="Close">'));
   assert.ok(html.includes('role="status"'));
   assert.ok(!html.includes("<audio"));
   assert.ok(html.includes("Nothing you do here is saved or sent."));