diff --git a/src/distill.js b/src/distill.js
index 64cde67..13b4088 100644
--- a/src/distill.js
+++ b/src/distill.js
@@ -293,7 +293,7 @@ export function distill(html, url = '', { view = null, type = '' } = {}) {
   const hidden = (el) =>
     el.getAttribute('hidden') !== null ||
     el.getAttribute('aria-hidden') === 'true' ||
-    /display:\s*none/.test(el.getAttribute('style') ?? '');
+    DISPLAY_NONE.test(el.getAttribute('style') ?? '');
 
   /** Subtree already emitted, skipped when the rest of the page is walked. */
   let done = null;
@@ -616,6 +616,9 @@ function number(blocks) {
  */
 const bodyOf = (document) => document.querySelector('body') ?? document.documentElement;
 
+/** CSS property names and keywords are case-insensitive: `DISPLAY : NONE` hides too. */
+const DISPLAY_NONE = /display\s*:\s*none/i;
+
 /**
  * HTML attribute names are ASCII case-insensitive, but linkedom keeps them as
  * written, so `<A HREF>` had no href, `<INPUT TYPE="hidden">` no type and
@@ -661,7 +664,7 @@ function cleanDocument(html, url = '', type = '') {
     if ((el.getAttribute('type') ?? '').toLowerCase() === 'hidden') el.remove();
   }
   for (const el of [...document.querySelectorAll('[style]')]) {
-    if (/display:\s*none/.test(el.getAttribute('style') ?? '')) el.remove();
+    if (DISPLAY_NONE.test(el.getAttribute('style') ?? '')) el.remove();
   }
   return { document, title };
 }
diff --git a/tests/distill.test.js b/tests/distill.test.js
index e6ca5b3..987d2ed 100644
--- a/tests/distill.test.js
+++ b/tests/distill.test.js
@@ -81,6 +81,25 @@ test('attribute names are matched case-insensitively, as HTML does', () => {
   }
 });
 
+test('a display:none style is matched case-insensitively, as CSS does', () => {
+  // CSS property names and keywords are case-insensitive and may have space
+  // before the colon, so each of these hides its content in a browser.
+  const html = `<html><head><title>Styles</title></head><body>
+    <h1>Styles</h1>
+    <p>shown</p>
+    <p style="DISPLAY:NONE">secret-upper</p>
+    <p style="Display: None">secret-mixed</p>
+    <p style="display : none">secret-spaced</p>
+  </body></html>`;
+  const view = render(distill(html, 'https://example.com/s'), { budget: 5000 }).text;
+  for (const out of [view, toMarkdown(html), toHTML(html)]) {
+    assert.ok(out.includes('shown'));
+    for (const secret of ['secret-upper', 'secret-mixed', 'secret-spaced']) {
+      assert.ok(!out.includes(secret), `${secret} leaked`);
+    }
+  }
+});
+
 test('raw mode emits real markdown with hrefs an agent can follow', () => {
   const md = toMarkdown(html);
   assert.ok(md.startsWith('# Fixture News'));