diff --git a/src/pytest_html/basereport.py b/src/pytest_html/basereport.py
index 4d1700f4..e5e61591 100644
--- a/src/pytest_html/basereport.py
+++ b/src/pytest_html/basereport.py
@@ -77,7 +77,9 @@ def __init__(self, title, config):
 
             collapsed = config.getini("render_collapsed")
             if collapsed:
-                self.set_data("collapsed", collapsed.split(","))
+                self.set_data(
+                    "collapsed", [outcome.lower() for outcome in collapsed.split(",")]
+                )
 
         @property
         def title(self):
diff --git a/src/pytest_html/scripts/storage.js b/src/pytest_html/scripts/storage.js
index 7033ee48..5af8171a 100644
--- a/src/pytest_html/scripts/storage.js
+++ b/src/pytest_html/scripts/storage.js
@@ -64,17 +64,17 @@ const getCollapsedCategory = (config) => {
         const url = new URL(window.location.href)
         const collapsedItems = new URLSearchParams(url.search).get('collapsed')
         switch (true) {
-            case collapsedItems === null:
-                categories = config || ['passed'];
+            case !config && collapsedItems === null:
+                categories = ['passed'];
                 break;
             case collapsedItems?.length === 0 || /^["']{2}$/.test(collapsedItems):
                 categories = [];
                 break;
-            case /^all$/.test(collapsedItems):
+            case /^all$/.test(collapsedItems) || (collapsedItems === null && /^all$/.test(config)):
                 categories = [...possibleFilters];
                 break;
             default:
-                categories = collapsedItems?.split(',').map(item => item.toLowerCase()) || [];
+                categories = collapsedItems?.split(',').map(item => item.toLowerCase()) || config;
                 break;
         }
     } else {
diff --git a/testing/test_integration.py b/testing/test_integration.py
index b94b70ee..079f738b 100644
--- a/testing/test_integration.py
+++ b/testing/test_integration.py
@@ -727,11 +727,12 @@ def test_falsy(self, pytester, test_file, param):
         assert_that(is_collapsed(page, "test_fail")).is_false()
         assert_that(is_collapsed(page, "test_error::setup")).is_false()
 
-    def test_render_collapsed(self, pytester, test_file):
+    @pytest.mark.parametrize("param", ["failed,error", "FAILED,eRRoR"])
+    def test_render_collapsed(self, pytester, test_file, param):
         pytester.makeini(
-            """
+            f"""
             [pytest]
-            render_collapsed = failed,error
+            render_collapsed = {param}
         """
         )
         pytester.makepyfile(test_file)
diff --git a/testing/unittest.js b/testing/unittest.js
index 0b23171f..17d6543d 100644
--- a/testing/unittest.js
+++ b/testing/unittest.js
@@ -195,16 +195,29 @@ describe('Storage tests', () => {
             expect(collapsedItems).to.eql(['failed', 'error', 'passed'])
         })
 
-        it('handles python config', () => {
-            mockWindow()
-            const collapsedItems = storageModule.getCollapsedCategory(['failed', 'error'])
-            expect(collapsedItems).to.eql(['failed', 'error'])
+        const config = [
+          { value: ['failed', 'error'], expected: ['failed', 'error'] },
+          { value: ['all'], expected: storageModule.possibleFilters }
+        ]
+        config.forEach(({value, expected}) => {
+            it(`handles python config: ${value}`, () => {
+                mockWindow()
+                const collapsedItems = storageModule.getCollapsedCategory(value)
+                expect(collapsedItems).to.eql(expected)
+            })
         })
 
-        it('handles python config precedence', () => {
-            mockWindow('collapsed=xpassed,xfailed')
-            const collapsedItems = storageModule.getCollapsedCategory(['failed', 'error'])
-            expect(collapsedItems).to.eql(['xpassed', 'xfailed'])
+        const precedence = [
+            {query: 'collapsed=xpassed,xfailed', config: ['failed', 'error'], expected: ['xpassed', 'xfailed']},
+            {query: 'collapsed=all', config: ['failed', 'error'], expected: storageModule.possibleFilters},
+            {query: 'collapsed=xpassed,xfailed', config: ['all'], expected: ['xpassed', 'xfailed']},
+        ]
+        precedence.forEach(({query, config, expected}, index) => {
+            it(`handles python config precedence ${index + 1}`, () => {
+                mockWindow(query)
+                const collapsedItems = storageModule.getCollapsedCategory(config)
+                expect(collapsedItems).to.eql(expected)
+            })
         })
 
         const falsy = [