Building Tabbed Elements

Module 4 of 6 in the KINETIC.email developer course. Create interactive tab interfaces in your emails to organize content and improve the reader's experience.

What are tabbed interfaces in email?

Tabbed interfaces are one of the most practical applications of the checkbox hack. They let recipients switch between content sections without scrolling, so you can include more content without a lengthy email and readers can focus on what interests them.

Common use cases

• Product category navigation
• Content segmentation, such as Details, Specs and Reviews
• Multi-step processes or forms
• Language or region selection
• Before and after comparisons

How they work

• Radio buttons track which tab is selected.
• Labels are styled as tab headers.
• CSS selectors show and hide content based on the selection.
• The :checked pseudo-class determines the active state.

Advantages and limitations

Tabs save vertical space, organize content, encourage engagement through interaction and can be used to track preferences. They only work in supporting clients, require a fallback for everyone else, need careful CSS selectors, and can increase overall email size.

Basic tabbed interface

<input type="radio" id="tab1" name="tabs" checked>
<input type="radio" id="tab2" name="tabs">
<div class="tabs">
  <label for="tab1">Tab 1</label>
  <label for="tab2">Tab 2</label>
</div>
<div class="content">
  <div id="content1" class="tab-content">...</div>
  <div id="content2" class="tab-content">...</div>
</div>

.tab-content {
  max-height: 0;
  opacity: 0;
  overflow: hidden;
}
#tab1:checked ~ .tabs label[for="tab1"] {
  background: #003366;
  color: white;
}
#tab1:checked ~* #content1 {
  max-height: 500px !important;
  opacity: 1 !important;
  overflow: visible !important;
}

How it works

1. Radio buttons as state storage: sharing one name means only one tab can be selected.
2. Labels as tab triggers: clicking a label checks its radio button.
3. Sibling selectors show content: #tab1:checked ~* #content1 reveals the matching panel; ~* targets the elements after the radio button.
4. Default selection: the checked attribute on the first radio makes content visible when the email opens.

The radios are hidden accessibly with position: absolute; opacity: 0;, and !important keeps the styles from being overridden by the email client.

Exercise 1: Build styled tabs

Group the radios with name="tabs", check the first one, hide every .panel with max-height: 0, opacity: 0 and overflow: hidden, then add :checked rules that reveal the right panel.

Tabs on mobile

Tab labels run out of space on small screens. The lesson shows two techniques. First, shrink the labels with a media query:

@media (max-width: 480px) {
  .tab { padding: 8px 12px; font-size: 11px; }
}

Second, swap text for icons: each label holds an icon span and a text span, the icon is hidden by default, and on mobile the icon shows while the text hides.

.tab .icon { display: none; }
@media (max-width: 480px) {
  .tab .icon { display: inline; }
  .tab .text { display: none; }
}

Mobile tab tips

• Keep tabs to 3 or 4 at most.
• Make touch targets at least 44 by 44 pixels.
• Use emoji or Unicode symbols for icons, since image-based icons may not load in all clients.
• Not all email clients support media queries, so test responsive tabs in your target clients.

Exercise 2: Build a tab fallback

Wrap the working tabs in the kinetic lightswitch from Module 3. Add a <label for="Kinetic"> reading "Toggle Lightswitch" to preview both versions, show .interactive with #Kinetic:checked ~ .interactive, and hide .fallback with #Kinetic:checked ~ .fallback.

Best practices

Design and user experience

• Use clear visual indicators for active and inactive tabs.
• Limit the number of tabs (2 to 4) so they fit on mobile.
• Write concise, descriptive tab labels.
• Always set a logical default tab with the checked attribute.

Technical implementation

• Always include the kinetic lightswitch for client detection and fallbacks.
• Give inputs and content blocks descriptive IDs.
• Optimize for touch with tap targets of at least 44 by 44 pixels.
• Test in every target email client.

Pitfalls to avoid

Forgetting fallback content, overly complex tab structures, leaving out !important on display properties, using too many tabs, unclear labels, and not checking tab content height, which causes layout jumps when switching tabs. For deeper insight, place unique tracking pixels or links in each tab to see which content resonates.

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Previous: The Kinetic Lightswitch. Next: Engagement Quiz. Back to the learning hub.