Active and focus states in CSS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ selector

intermediate

Identify the selector for keyboard focus

Which CSS selector correctly styles an element when it receives keyboard focus?

A :visited

B :focus

C :active

D :hover

💡 Hint

Think about which state applies when you tab to an element.

The :focus selector applies styles when an element receives keyboard focus, such as when tabbing through links or form controls.

🧠 Conceptual

intermediate

Purpose of :active state

What does the :active CSS pseudo-class represent?

A When an element has been visited

B When an element is hovered by the mouse

C When an element is focused by keyboard

D When an element is being clicked or pressed

💡 Hint

Think about the moment you press down on a button.

The :active state applies while the user is pressing down on an element, such as clicking a button or link.

❓ rendering

advanced

Visual difference between :focus and :active

Given this CSS, what color will the button text be when it is focused but not pressed?

CSS

button:focus { color: blue; }
button:active { color: red; }

A Blue

B Red

C Black (default)

D Purple

💡 Hint

Focus and active states can have different styles; only one applies at a time.

When the button is focused but not pressed, only :focus applies, so the text color is blue.

❓ accessibility

advanced

Why is visible focus important?

Why should web developers always provide a visible focus style for interactive elements?

A To improve mouse usability

B To make the page load faster

C To help keyboard users know which element is active

D To prevent screen readers from reading content

💡 Hint

Think about users who navigate without a mouse.

Visible focus helps keyboard users see which element is currently selected, improving accessibility.

📝 Syntax

expert

Identify the error in this CSS for active and focus states

What error does this CSS cause?

button:focus, :active { background: yellow; }

CSS

button:focus, :active { background: yellow; }

A SyntaxError: Missing element before :active selector

B No error; styles apply to button focus and any active element

C TypeError: Invalid pseudo-class usage

D Runtime error: Cannot apply styles to :active

💡 Hint

Check if all selectors have an element or class before the pseudo-class.

The selector :active without an element or class is invalid in this context and causes a syntax error. It should be button:active to target buttons.

Practice

1. What does the :active pseudo-class in CSS represent?

easy

A. An element that is currently selected by keyboard navigation

B. An element that is disabled and cannot be interacted with

C. An element that is hovered by the mouse pointer

D. An element being clicked or pressed by the user

Solution

1. Step 1: Understand the meaning of :active

   The :active pseudo-class applies when the user clicks or presses an element, like a button being pressed down.

2. Step 2: Compare with other states

   :focus is for keyboard or mouse selection, :hover is for mouse hover, and disabled elements do not have :active state.

3. Final Answer:

   An element being clicked or pressed by the user -> Option D

4. Quick Check:

   :active = clicked element [OK]

Hint: Active means element is being clicked or pressed [OK]

Common Mistakes:

• Confusing :active with :focus
• Thinking :active means hover
• Assuming disabled elements have :active

2. Which CSS selector correctly styles a button when it is focused by keyboard or mouse?

easy

A. button:focus { outline: 2px solid blue; }

B. button:hover { outline: 2px solid blue; }

C. button:active { outline: 2px solid blue; }

D. button:selected { outline: 2px solid blue; }

Solution

1. Step 1: Identify the correct pseudo-class for focus

   The :focus selector applies styles when an element is selected by keyboard or mouse, such as tabbing to a button.

2. Step 2: Check other options

   :active is for clicking, :hover is for mouse hover, and :selected is not a valid CSS pseudo-class.

3. Final Answer:

   button:focus { outline: 2px solid blue; } -> Option A

4. Quick Check:

   :focus styles selected element [OK]

Hint: Focus uses :focus selector, not :active or :hover [OK]

Common Mistakes:

• Using :active instead of :focus for keyboard selection
• Confusing :hover with :focus
• Using invalid :selected pseudo-class

3. Given this CSS and HTML, what color will the button text be when the button is clicked and held?

button:active { color: red; }
button:focus { color: blue; }

Click me

medium

A. Red

B. Purple

C. Black (default)

D. Blue

Solution

1. Step 1: Determine states during click-and-hold

   When the button is clicked and held, it matches both :active and :focus.

2. Step 2: Analyze CSS cascade

   Both selectors have the same specificity. The rule declared later in the CSS wins. Here, button:focus comes after button:active, so color: blue applies.

3. Step 3: Verify actual browser behavior

   However, in most browsers, the :active state takes precedence during the click, so the color is red while the button is pressed.

4. Final Answer:

   Red -> Option A

5. Quick Check:

   :active styles apply during click [OK]

Hint: :active styles apply while clicking, overriding :focus [OK]

Common Mistakes:

• Believing :active always overrides :focus
• Ignoring CSS declaration order
• Assuming default color applies

4. This CSS code is intended to style a link when focused or active, but the active style never appears. What is the problem?

a:active { background-color: green; }
a:focus { background-color: yellow; }

medium

A. The :active selector must come before :focus in CSS

B. The link must have tabindex attribute for :active to work

C. The :focus style overrides :active because it comes later

D. The :active selector only works on buttons, not links

Solution

1. Step 1: Check CSS rule order and specificity

   Both a:focus and a:active have same specificity. The later rule in CSS overrides earlier if both apply.

2. Step 2: Understand when :active and :focus apply

   When clicking a link, it is both active and focused. Since a:focus is declared after a:active, its background color overrides the active style.

3. Step 3: Fix by placing :active after :focus

   Reordering CSS to put a:active after a:focus ensures active style shows during click.

4. Final Answer:

   The :focus style overrides :active because it comes later -> Option C

5. Quick Check:

   Later CSS rule overrides earlier [OK]

Hint: Later CSS rules override earlier ones with same specificity [OK]

Common Mistakes:

• Thinking :active only works on buttons
• Believing tabindex affects :active
• Ignoring CSS rule order

5. You want to create a button that shows a blue outline when focused for accessibility, and a red background only while it is being clicked. Which CSS code correctly achieves this?

hard

A. button:active { outline: 3px solid blue; } button:focus { background-color: red; }

B. button:focus { outline: 3px solid blue; } button:active { background-color: red; }

C. button:focus, button:active { outline: 3px solid blue; background-color: red; }

D. button { outline: 3px solid blue; background-color: red; }

Solution

1. Step 1: Separate focus and active styles

   Focus should show a blue outline, so button:focus { outline: 3px solid blue; } is correct. Active should show red background only while clicking, so button:active { background-color: red; } is correct.

2. Step 2: Check other options for correctness

   button:active { outline: 3px solid blue; } button:focus { background-color: red; } swaps styles incorrectly. button:focus, button:active { outline: 3px solid blue; background-color: red; } applies both styles together, which is wrong. button { outline: 3px solid blue; background-color: red; } applies styles always, ignoring states.

3. Final Answer:

   button:focus { outline: 3px solid blue; } button:active { background-color: red; } -> Option B

4. Quick Check:

   Separate :focus and :active styles [OK]

Hint: Use separate selectors for :focus outline and :active background [OK]

Common Mistakes:

• Combining :focus and :active styles incorrectly
• Applying styles always without pseudo-classes
• Swapping focus and active styles