Focus-within variant in Tailwind - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ selector

intermediate

What does the focus-within variant do in Tailwind CSS?

Choose the correct description of the focus-within variant in Tailwind CSS.

A Applies styles when any child element inside the element is focused.

B Applies styles when the element is active (clicked).

C Applies styles only when the element is hovered.

D Applies styles when an element itself is focused.

💡 Hint

Think about when the styles apply related to focus inside nested elements.

The focus-within variant applies styles to a parent element when any of its child elements receive focus. This helps style containers based on focus inside them.

❓ rendering

intermediate

What visual effect will this Tailwind code produce when you focus inside the input?

Given this HTML and Tailwind CSS, what will happen when the user clicks inside the input box?

Tailwind

<div class="border-2 border-gray-300 focus-within:border-blue-500 p-4">
  <label for="name" class="block mb-2">Name</label>
  <input id="name" type="text" class="border p-2 w-full" />
</div>

A Only the input border changes color to blue.

B The label text color changes to blue.

C The border around the entire div changes from gray to blue.

D Nothing changes visually on focus.

💡 Hint

Look at which element has the focus-within class and what it styles.

The focus-within:border-blue-500 applies to the div. When the input inside is focused, the div's border color changes to blue.

📝 Syntax

advanced

Which Tailwind class correctly applies a background color when a container or its children are focused?

Select the correct Tailwind class to change background color on focus within the container.

A bg-gray-100 focus-within:bg-yellow-200

B bg-gray-100 focus:bg-yellow-200

C bg-gray-100 hover-within:bg-yellow-200

D bg-gray-100 active-within:bg-yellow-200

💡 Hint

Remember the exact variant name for focus inside children.

focus-within is the correct variant to apply styles when the container or any child is focused. Other variants like focus apply only to the element itself.

❓ accessibility

advanced

Why is using focus-within helpful for accessibility in forms?

Choose the best reason why focus-within improves accessibility for users navigating forms.

A It disables all other inputs when one input is focused.

B It highlights the entire form section when any input inside is focused, helping users see context.

C It automatically submits the form when an input is focused.

D It hides labels when inputs are focused to reduce clutter.

💡 Hint

Think about how focus indication helps users understand where they are on the page.

focus-within allows styling of a container to visually group focused inputs, making it easier for keyboard and screen reader users to understand form structure.

❓ layout

expert

What is the effect of combining focus-within with Flexbox in this example?

Consider this HTML and Tailwind CSS snippet. What happens to the layout when the input inside the flex container is focused?

Tailwind

<div class="flex gap-4 p-4 border-2 border-gray-400 focus-within:border-green-600">
  <label for="email" class="flex-1">Email</label>
  <input id="email" type="email" class="flex-1 border p-2" />
</div>

A The flex container switches to column layout on focus.

B The input expands to fill the container when focused, breaking the layout.

C The label disappears when the input is focused.

D The border color of the flex container changes to green, but the layout stays the same.

💡 Hint

Focus on what focus-within changes and how Flexbox behaves by default.

The focus-within:border-green-600 changes the border color of the flex container on focus inside. Flexbox layout remains unchanged because no layout properties are altered.

Practice

1.

What does the focus-within variant in Tailwind CSS do?

easy

A. It applies styles to a parent element when any child element inside it is focused.

B. It applies styles only to the focused child element itself.

C. It applies styles to all sibling elements of the focused element.

D. It disables focus styles on all child elements.

Solution

1. Step 1: Understand the focus-within behavior

   The focus-within variant targets the parent element when any child inside it receives focus.

2. Step 2: Compare options with this behavior

   Only It applies styles to a parent element when any child element inside it is focused. correctly describes this behavior, while others describe different or incorrect behaviors.

3. Final Answer:

   It applies styles to a parent element when any child element inside it is focused. -> Option A

4. Quick Check:

   focus-within targets parent on child focus [OK]

Hint: Remember: focus-within styles the parent, not the child [OK]

Common Mistakes:

• Thinking focus-within styles only the focused child
• Confusing focus-within with focus-visible
• Assuming it styles siblings of the focused element

2.

Which of the following is the correct Tailwind CSS syntax to change the background color of a <div> when any child inside it is focused?

<div class="?">
  <input type="text" />
</div>

easy

A. focus-child:bg-blue-200

B. focus:bg-blue-200

C. focus-within:bg-blue-200

D. focus-visible:bg-blue-200

Solution

1. Step 1: Identify the correct variant for parent styling on child focus

   The focus-within variant applies styles to the parent when any child is focused.

2. Step 2: Match the variant with the correct syntax

   focus-within:bg-blue-200 uses focus-within:bg-blue-200, which is the correct Tailwind syntax for this effect.

3. Final Answer:

   focus-within:bg-blue-200 -> Option C

4. Quick Check:

   Parent focus style on child focus = focus-within:bg-color [OK]

Hint: Use focus-within: prefix to style parent on child focus [OK]

Common Mistakes:

• Using focus: which styles only the focused element
• Using non-existent focus-child variant
• Confusing focus-visible with focus-within

3.

Given this HTML and Tailwind CSS, what will happen when the user clicks inside the input?

<div class="border-2 border-gray-300 focus-within:border-green-500 p-4">
  <input type="text" class="outline-none" />
</div>

medium

A. The div's background color changes to green.

B. The input's border color changes to green when focused.

C. Nothing changes because focus-within doesn't work on div.

D. The div's border color changes to green when the input is focused.

Solution

1. Step 1: Understand focus-within effect on the div

   The div has a gray border by default and changes border color to green when any child (input) is focused.

2. Step 2: Identify what changes on input focus

   When the input is focused, the div's border changes to green, not the input's border or background color.

3. Final Answer:

   The div's border color changes to green when the input is focused. -> Option D

4. Quick Check:

   focus-within changes parent border color [OK]

Hint: focus-within changes parent styles, not child styles [OK]

Common Mistakes:

• Thinking input border changes instead of div border
• Assuming background color changes without code
• Believing focus-within doesn't apply to div

4.

What is wrong with this Tailwind CSS usage if the goal is to highlight the parent div's border when the input inside is focused?

<div class="border-2 border-gray-300 focus:border-green-500 p-4">
  <input type="text" class="outline-none" />
</div>

medium

A. Missing outline-none on the input element.

B. Using focus: on the parent instead of focus-within:.

C. The border color classes are in the wrong order.

D. The input element needs a focus-visible class.

Solution

1. Step 1: Identify the variant used on the parent div

   The parent div uses focus:border-green-500, which applies styles only when the div itself is focused.

2. Step 2: Understand the correct variant for child focus affecting parent

   To style the parent when a child is focused, focus-within: must be used instead of focus:.

3. Final Answer:

   Using focus: on the parent instead of focus-within:. -> Option B

4. Quick Check:

   Parent highlight on child focus needs focus-within: [OK]

Hint: Use focus-within: on parent, not focus: for child focus styles [OK]

Common Mistakes:

• Using focus: instead of focus-within:
• Thinking input needs focus-visible class
• Believing border order affects focus styles

5.

You want to create a form section that highlights its border in blue when any input or textarea inside is focused. Which Tailwind CSS class combination correctly achieves this?

<section class="?">
  <input type="text" />
  <textarea></textarea>
</section>

hard

A. border-2 border-gray-400 focus-within:border-blue-600 p-6 rounded-lg

B. border-2 border-gray-400 focus:border-blue-600 p-6 rounded-lg

C. border-2 border-gray-400 focus-visible:border-blue-600 p-6 rounded-lg

D. border-2 border-gray-400 hover-within:border-blue-600 p-6 rounded-lg

Solution

1. Step 1: Identify the variant that styles parent on child focus

   The focus-within: variant applies styles to the parent when any child element is focused.

2. Step 2: Check the class combinations for correct usage

   border-2 border-gray-400 focus-within:border-blue-600 p-6 rounded-lg uses focus-within:border-blue-600 on the section, which highlights the border when input or textarea inside is focused.

3. Final Answer:

   border-2 border-gray-400 focus-within:border-blue-600 p-6 rounded-lg -> Option A

4. Quick Check:

   Parent border highlight on child focus = focus-within:border-color [OK]

Hint: Use focus-within: on container to highlight on any child focus [OK]

Common Mistakes:

• Using focus: which styles only the container if focused
• Using focus-visible: which targets keyboard focus only
• Using non-existent hover-within: variant