Universal selector in CSS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all elements on the page.

CSS

[1] { margin: 0; padding: 0; }

Drag options to blanks, or click blank then click option'

A*

B#

C.

Dhtml

Attempts:

3 left

💡 Hint

Common Mistakes

Using '#' which selects an element by ID.

Using '.' which selects elements by class.

Using 'html' which selects only the html element.

The universal selector in CSS is the asterisk (*). It selects all elements on the page.

2fill in blank

medium

Complete the code to apply a border to all elements.

CSS

[1] { border: 1px solid black; }

Drag options to blanks, or click blank then click option'

A*

B#all

C.all

Dbody

Attempts:

3 left

💡 Hint

Common Mistakes

Using '.all' which selects elements with class 'all' only.

Using '#all' which selects an element with ID 'all' only.

Using 'body' which selects only the body element.

The universal selector '*' applies styles to every element on the page, so all elements get the border.

3fill in blank

hard

Fix the error in the code to select all elements and set font size.

CSS

[1] { font-size: 16px; }

Drag options to blanks, or click blank then click option'

Afont

B#

C.

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '#' or '.' which select IDs or classes, not all elements.

Using a word like 'font' which is not a selector.

The universal selector '*' selects all elements. '#' and '.' are for IDs and classes, and 'font' is not a selector.

4fill in blank

hard

Fill both blanks to select all elements and set margin and padding to zero.

CSS

[1] { margin: 0; padding: [2]; }

Drag options to blanks, or click blank then click option'

A*

B5px

C0

Dauto

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class or ID selector instead of the universal selector.

Setting padding to a non-zero value when the goal is to remove it.

The universal selector '*' selects all elements. Setting padding to '0' removes all padding.

5fill in blank

hard

Fill all three blanks to select all elements, set box-sizing, and remove margin.

CSS

[1] { box-sizing: [2]; margin: [3]; }

Drag options to blanks, or click blank then click option'

Ahtml

Bborder-box

C0

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'html' instead of '*' to select all elements.

Using incorrect box-sizing values like 'content-box'.

Not setting margin to zero when the goal is to remove it.

The universal selector '*' selects all elements. 'border-box' makes sizing include borders and padding. Setting margin to '0' removes default margins.

Practice

1. What does the CSS universal selector * do?

easy

A. Selects elements with a specific class

B. Selects only div elements

C. Selects all elements on the page

D. Selects elements with a specific ID

Solution

1. Step 1: Understand the universal selector symbol

   The * symbol in CSS means "all elements" without exception.

2. Step 2: Apply the selector meaning

   Using * targets every element on the page, regardless of tag, class, or ID.

3. Final Answer:

   Selects all elements on the page -> Option C

4. Quick Check:

   Universal selector = all elements [OK]

Hint: Remember * means every element on the page [OK]

Common Mistakes:

• Thinking * selects only specific tags
• Confusing * with class or ID selectors
• Assuming * targets only visible elements

2. Which of the following is the correct syntax to apply a margin of 0 to all elements using the universal selector?

easy

A. # * { margin: 0; }

B. . * { margin: 0; }

C. all { margin: 0; }

D. * { margin: 0; }

Solution

1. Step 1: Identify the universal selector syntax

   The universal selector is just * without any prefix like dot or hash.

2. Step 2: Check the CSS rule format

   The correct CSS rule to apply margin 0 to all elements is * { margin: 0; }.

3. Final Answer:

   * { margin: 0; } -> Option D

4. Quick Check:

   Universal selector syntax = * { ... } [OK]

Hint: Universal selector is just * without dot or hash [OK]

Common Mistakes:

• Adding dot or hash before *
• Using invalid selector names like 'all'
• Forgetting curly braces

3. Given this CSS code:

* { padding: 10px; }
p { padding: 5px; }

What will be the padding of a paragraph (<p>) element?

medium

A. 10px

B. 5px

C. 15px

D. 0px

Solution

1. Step 1: Understand selector specificity

   The universal selector * applies padding 10px to all elements, but the p selector is more specific.

2. Step 2: Apply CSS specificity rules

   Since p selector is more specific than *, the paragraph's padding will be 5px, overriding the universal selector.

3. Final Answer:

   5px -> Option B

4. Quick Check:

   More specific selector wins = 5px [OK]

Hint: More specific selector overrides * [OK]

Common Mistakes:

• Assuming * always overrides other selectors
• Adding padding values instead of overriding
• Ignoring CSS specificity rules

4. You wrote this CSS:

* { font-size: 16px }

But the browser ignores it and uses default font sizes. What is the likely error?

medium

A. CSS file not linked properly

B. Universal selector cannot set font size

C. Font size must be in quotes

D. Missing semicolon after 16px

Solution

1. Step 1: Check CSS syntax

   The CSS rule * { font-size: 16px } is syntactically valid; a trailing semicolon is optional at the end of a rule.

2. Step 2: Understand common issues

   If valid CSS is ignored by the browser, the stylesheet is likely not linked properly in the HTML with a <link rel="stylesheet" href="..."> tag.

3. Final Answer:

   CSS file not linked properly -> Option A

4. Quick Check:

   No styles applied? Check <link> tag [OK]

Hint: If * styles not applying, verify CSS file link [OK]

Common Mistakes:

• Thinking universal selector can't style fonts
• Using quotes around numeric values
• Ignoring CSS file linking issues

5. You want to reset margin and padding for all elements but keep links (<a>) with no margin and 5px padding. Which CSS achieves this?

hard

A. * { margin: 0; padding: 0; } a { padding: 5px; }

B. a { margin: 10px; padding: 5px; } * { margin: 0; padding: 0; }

C. * { margin: 0; padding: 5px; } a { margin: 0; padding: 0; }

D. * { margin: 0; padding: 0; a { padding: 5px; } }

Solution

1. Step 1: Reset all elements margin and padding

   The universal selector * { margin: 0; padding: 0; } sets margin and padding to zero for all elements.

2. Step 2: Override padding for links

   The selector a { padding: 5px; } specifically sets padding to 5px for all <a> elements, overriding the universal selector.

3. Final Answer:

   * { margin: 0; padding: 0; } a { padding: 5px; } -> Option A

4. Quick Check:

   Specific selector overrides universal [OK]

Hint: Use * first, then override with specific selector [OK]

Common Mistakes:

• Placing universal selector after specific selector
• Nesting selectors incorrectly
• Setting wrong padding values