diff --git a/frontend/website/cypress/e2e/set-layout.cy.ts b/frontend/website/cypress/e2e/set-layout.cy.ts
index aad6b24..0e5a04b 100644
--- a/frontend/website/cypress/e2e/set-layout.cy.ts
+++ b/frontend/website/cypress/e2e/set-layout.cy.ts
@@ -51,7 +51,7 @@ describe('set element layout', () => {
     interceptAuthenticatedUser()
   })
 
-  it('opens a set from the dashboard and shows its full hierarchy', () => {
+  it('opens a set with a foldable element hierarchy', () => {
     cy.intercept('GET', '**/api/sets', {
       statusCode: 200,
       body: { sets: [{ id: 41, name: 'Bible' }] },
@@ -79,13 +79,35 @@ describe('set element layout', () => {
     cy.get('[data-element-id="1"] > .element-node__card')
       .should('contain.text', 'Genesis')
       .and('contain.text', 'book')
+      .and('have.attr', 'aria-expanded', 'false')
+      .and('have.attr', 'aria-controls', 'element-children-1')
+    cy.get('[data-element-id="2"] > .element-node__card').should(
+      'not.match',
+      'button',
+    )
+    cy.get('[data-element-id="3"]').should('not.exist')
+
+    cy.get('[data-element-id="1"] > button.element-node__card').click()
+    cy.get('[data-element-id="1"] > .element-node__card').should(
+      'have.attr',
+      'aria-expanded',
+      'true',
+    )
     cy.get('[data-element-id="1"] > ol > li').then(($nodes) => {
       expect([...$nodes].map((node) => node.dataset.elementId)).to.deep.equal([
         '3',
         '5',
       ])
     })
-    cy.get('[data-element-id="3"] > ol > li')
+    cy.get('[data-element-id="4"]').should('not.exist')
+
+    cy.get('[data-element-id="3"] > button.element-node__card').click()
+    cy.get('[data-element-id="3"] > .element-node__card').should(
+      'have.attr',
+      'aria-expanded',
+      'true',
+    )
+    cy.get('#element-children-3 > li')
       .should('have.length', 1)
       .and('have.attr', 'data-element-id', '4')
     cy.contains('.element-node__card', 'Chapter 1')
@@ -93,6 +115,15 @@ describe('set element layout', () => {
       .find('.element-node__kind')
       .should('have.text', 'Chapter_sections-v2')
       .and('have.css', 'text-transform', 'none')
+
+    cy.get('[data-element-id="1"] > button.element-node__card').click()
+    cy.get('[data-element-id="3"]').should('not.exist')
+
+    cy.get('[data-element-id="1"] > button.element-node__card').click()
+    cy.get('[data-element-id="4"] > .element-node__card').should(
+      'contain.text',
+      'Chapter 1',
+    )
   })
 
   it('shows loading and empty layout states', () => {
@@ -183,6 +214,8 @@ describe('set element layout', () => {
     cy.wait('@me')
     cy.wait('@layout')
 
+    cy.get('[data-element-id="1"] > button.element-node__card').click()
+    cy.get('[data-element-id="3"] > button.element-node__card').click()
     cy.contains('.element-node__card', 'Chapter 1').should('be.visible')
     cy.document().then((document) => {
       expect(document.documentElement.scrollWidth).to.be.at.most(