First-child and last-child in CSS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the CSS selector :first-child do?

It selects the very first child element inside its parent element.

beginner

What does the CSS selector :last-child do?

It selects the very last child element inside its parent element.

intermediate

Can :first-child select the first element of a specific type only?

No, :first-child selects the first child regardless of its type. To select the first of a specific type, use :first-of-type.

beginner

How would you style only the first paragraph inside a <div> using :first-child?

Use div p:first-child { /* styles */ }. This styles a p only if it is the first child of the div.

beginner

What happens if you use :last-child on an element that is not the last child?

The style will not apply because :last-child only matches elements that are the last child of their parent.

Which CSS selector targets the first child element of its parent?

A :first-child

B :last-child

C :nth-child(2)

D :only-child

:first-child selects the first child element inside its parent.

What does li:last-child select?

A The last <code>li</code> inside its parent

B All <code>li</code> elements

C The first <code>li</code> inside its parent

D Only <code>li</code> elements with no siblings

li:last-child selects the li element that is the last child of its parent.

If a p is the second child of a div, will div p:first-child style it?

A Yes, always

B No, only if it is the first child

C Yes, if it is the only <code>p</code>

D No, it styles the last child

:first-child matches only if the element is the first child of its parent.

Which selector would style the last li in a list?

A li:first-child

B li:nth-child(1)

C li:last-child

D li:only-child

li:last-child targets the last li inside its parent.

What is true about :first-child and :last-child selectors?

A They select all children of a parent.

B They select elements by their class name.

C They select elements by their ID.

D They select elements based on their position among siblings.

Both selectors select elements based on their position as first or last child among siblings.

Explain how the :first-child and :last-child selectors work in CSS.

Think about how these selectors depend on the element's position among siblings.

Describe a real-life example where you would use :first-child or :last-child in styling a webpage.

Consider menus, lists, or groups of items on a page.

Practice

1. What does the CSS selector :first-child do?

easy

A. It selects the last child element inside its parent.

B. It selects the first child element inside its parent.

C. It selects all child elements except the first.

D. It selects only the parent element.

Solution

1. Step 1: Understand the selector purpose

   The :first-child selector targets only the very first child element within a parent container.

2. Step 2: Compare with other options

   :last-child targets the last child, others do not match the description.

3. Final Answer:

   It selects the first child element inside its parent. -> Option B

4. Quick Check:

   :first-child = first child selected [OK]

Hint: First-child always picks the very first element inside a parent [OK]

Common Mistakes:

• Confusing :first-child with :last-child
• Thinking it selects all children
• Assuming it selects the parent

2. Which of the following is the correct CSS syntax to style the last child of a <ul> list?

easy

A. ul > li:last-child { color: red; }

B. ul:last-child { color: red; }

C. ul li:first-child { color: red; }

D. ul:last-child li { color: red; }

Solution

1. Step 1: Identify the target element

   The goal is to style the last <li> inside a <ul>, so the selector must target li elements that are last children.

2. Step 2: Check selector correctness

   ul > li:last-child correctly selects the last li directly inside ul. Other options either select the wrong element or use incorrect syntax.

3. Final Answer:

   ul > li:last-child { color: red; } -> Option A

4. Quick Check:

   Correct syntax for last child inside ul = ul > li:last-child { color: red; } [OK]

Hint: Use parent > child:last-child to style last child only [OK]

Common Mistakes:

• Using :last-child on the parent instead of the child
• Confusing :first-child with :last-child
• Missing the direct child combinator >

3. Given this HTML:

<ul>
  <li>Apple</li>
  <li>Banana</li>
  <li>Cherry</li>
</ul>

And CSS:

li:first-child { color: blue; }
li:last-child { color: green; }

What color will the text "Banana" have when rendered?

medium

A. Blue

B. Green

C. Black (default)

D. Both blue and green

Solution

1. Step 1: Identify which elements get styled

   li:first-child styles the first li (Apple), li:last-child styles the last li (Cherry).

2. Step 2: Determine Banana's position

   Banana is the second li, so it is neither first nor last child, so no color styles apply.

3. Final Answer:

   Black (default) -> Option C

4. Quick Check:

   Banana is middle child, no color applied [OK]

Hint: Only first or last child get styles, middle ones stay default [OK]

Common Mistakes:

• Assuming all list items get styled
• Confusing order of children
• Thinking styles cascade to siblings

4. This CSS code is intended to color the first and last paragraphs inside a <section> green and blue respectively:

section p:first-child { color: green; }
section p:last-child { color: blue; }

But only the first paragraph turns green, the last paragraph stays black. Why?

medium

A. Because the colors green and blue are invalid.

B. Because the CSS syntax is incorrect.

C. Because section cannot contain paragraphs.

D. Because p elements are not the first or last child of section.

Solution

1. Step 1: Understand :first-child and :last-child context

   These selectors check if the element is the very first or last child of its parent, regardless of type.

2. Step 2: Check if p is first or last child

   If other elements (like headings or divs) come before or after the p, then p is not first or last child, so styles won't apply.

3. Final Answer:

   Because p elements are not the first or last child of section. -> Option D

4. Quick Check:

   :first-child and :last-child depend on element position, not type [OK]

Hint: Check if element is truly first/last child, not just first/last of type [OK]

Common Mistakes:

• Assuming :first-child means first of type
• Ignoring other sibling elements
• Thinking syntax is wrong when it's position issue

5. You want to style the first and last <li> elements inside every <ul> differently, but only if the <li> is also the first or last child of its parent. Which CSS selectors correctly achieve this?

hard

A. ul > li:first-child { font-weight: bold; } and ul > li:last-child { font-style: italic; }

B. ul:first-child li { font-weight: bold; } and ul:last-child li { font-style: italic; }

C. ul li:first-child { font-weight: bold; } and ul li:last-child { font-style: italic; }

D. ul li:first-of-type { font-weight: bold; } and ul li:last-of-type { font-style: italic; }

Solution

1. Step 1: Understand the requirement

   We want to style only li elements that are the first or last child of their ul parent.

2. Step 2: Choose selectors that target direct children and correct position

   ul > li:first-child and ul > li:last-child select li elements that are direct children and first or last child respectively. This matches the requirement exactly.

3. Step 3: Evaluate other options

   ul li:first-child { font-weight: bold; } and ul li:last-child { font-style: italic; } misses the direct child combinator, which can cause incorrect matches if nested lists exist. ul:first-child li { font-weight: bold; } and ul:last-child li { font-style: italic; } incorrectly applies :first-child to ul. ul li:first-of-type { font-weight: bold; } and ul li:last-of-type { font-style: italic; } uses :first-of-type which selects first li regardless of position among siblings.

4. Final Answer:

   ul > li:first-child { font-weight: bold; } and ul > li:last-child { font-style: italic; } -> Option A

5. Quick Check:

   Direct child + :first-child and :last-child = ul > li:first-child { font-weight: bold; } and ul > li:last-child { font-style: italic; } [OK]

Hint: Use direct child combinator > with :first-child and :last-child [OK]

Common Mistakes:

• Omitting > combinator causing wrong matches
• Confusing :first-child with :first-of-type
• Applying selectors to wrong parent element