Decide whether content should be hidden
An expandable section lets a visitor reveal or hide a block of content without leaving the page. It can help organize a lengthy set of optional details, such as answers to common questions or explanations of service choices. It is less helpful when visitors need to read every section to complete a task. If the page is short, showing the content may be simpler.
Before adding expanders, ask what a visitor needs to know at a glance. Keep essential instructions, deadlines, and warnings visible rather than placing them behind a control. If several sections form a sequence, a straightforward page with descriptive headings may make that sequence clearer. Expanders should solve a specific reading problem, not merely make the page look shorter.
Give every section a clear label
A collapsed section offers only its label as a clue to what it contains. Write labels that describe the hidden content: “What to bring to an appointment” is more useful than “More information.” Keep related labels consistent so visitors can scan them and decide what to open. Avoid putting several unrelated topics under one vague label.
Make the control look and behave like something a visitor can operate. A button is generally the right choice for a custom expander because it represents an action on the current page. Place it within an appropriate heading when the expandable section is part of the page outline. The heading identifies the topic; the button lets the visitor reveal its details. Do not use a link that points nowhere merely to imitate a button.
A visual indicator, such as a chevron, can reinforce the open or closed state. Do not make that shape or its color the only clue. The control’s accessible state should also change when the panel opens or closes, so a screen reader user receives the same basic information.
Keep controls and panels connected
For a custom expandable section, give each button an accessible name and an accurate expanded state. The aria-expanded attribute can report whether its panel is currently open. If you use aria-controls to identify the panel, make sure it points to that panel’s unique ID. Update the visible panel and the button state together; a control that says it is expanded while its content remains hidden is confusing.
Use ordinary document structure inside the revealed panel. Paragraphs, lists, and links should remain in a sensible reading order. When a panel is collapsed, its hidden links and controls should not remain in the keyboard tab sequence. When it opens, visitors should be able to reach them normally. Opening a section usually does not require moving keyboard focus: the visitor can continue from the button into the revealed content.
For a simple page, the built-in HTML details and summary elements may be worth considering. They provide disclosure behavior without a custom script, though appearance and interaction should still be checked in the browsers and assistive technology relevant to your audience. If you choose a custom component, build and test its behavior rather than relying on its visual design alone.
Check the experience with real content
Fill the sections with the content they will actually hold before deciding the design works. A short answer and a long answer may need different spacing. Make sure opening a panel does not obscure its text behind a fixed header or create a confusing jump. On a narrow screen or at enlarged text sizes, labels should wrap without overlapping the indicator or nearby controls.
Test with a keyboard: move to each button with Tab, activate it with Enter and Space, and check that the content appears and can be reached in a logical order. Close it and confirm that hidden controls can no longer receive focus. If your design allows multiple panels to stay open, check that each one reports its own state correctly. Read the page with sections closed as well as open. Visitors should still be able to tell what information is available and which section to open next.
