Box model calculation in CSS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the width of the box to 200 pixels.

CSS

div {
  width: [1];
}

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

A200

Bpx200

Cwidth: 200px

D200px

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to add units like px

Writing the property name again inside the value

The width property requires a length value with units like px. So 200px is correct.

2fill in blank

medium

Complete the code to add 10 pixels of padding inside the box.

CSS

div {
  padding: [1];
}

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

A10px

Bpadding: 10px

Cpx10

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using just a number without units

Repeating the property name inside the value

Padding needs a length value with units, so 10px is correct.

3fill in blank

hard

Fix the error in the code to correctly set the margin to 15 pixels.

CSS

div {
  margin: [1];
}

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

Apx15

B15px

Cmargin 15px

D15

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving out units

Writing property name inside the value

The margin property needs a length with units like 15px. Just 15 is not valid.

4fill in blank

hard

Fill both blanks to set the border width to 5 pixels and border style to solid.

CSS

div {
  border-width: [1];
  border-style: [2];
}

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

A5px

Bsolid

Cdotted

D10px

Attempts:

3 left

💡 Hint

Common Mistakes

Using a number without units for border-width

Choosing a border style that is not solid

The border width needs a size with units like 5px, and the border style should be solid to show a solid line.

5fill in blank

hard

Fill all three blanks to create a box with width 100px, padding 20px, and margin 30px.

CSS

div {
  width: [1];
  padding: [2];
  margin: [3];
}

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

A100px

B20px

C30px

D50px

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up padding and margin values

Forgetting units on any size

Width is set to 100px, padding to 20px, and margin to 30px to create the desired box spacing.

Practice

1. Which parts of the CSS box model add space inside the element's border?

easy

A. Margin and padding

B. Padding and content

C. Margin and border

D. Border and margin

Solution

1. Step 1: Understand box model parts

   The box model has content, padding, border, and margin. Padding is inside the border, margin is outside.

2. Step 2: Identify inside spaces

   Padding adds space inside the border, content is inside padding. Margin is outside the border.

3. Final Answer:

   Padding and content -> Option B

4. Quick Check:

   Inside space = padding + content [OK]

Hint: Padding is inside border; margin is outside [OK]

Common Mistakes:

• Confusing margin as inside space
• Thinking border adds inside space
• Mixing padding with margin

2. Given this CSS, what is the total width of the element?

width: 200px; padding: 10px; border: 5px solid; margin: 20px;

easy

A. 250px

B. 270px

C. 270px plus margin

D. 250px plus margin

Solution

1. Step 1: Calculate width including padding and border

   Width = content width (200px) + padding left+right (10px*2=20px) + border left+right (5px*2=10px) = 230px.

2. Step 2: Add margin outside the box

   Margin left+right = 20px*2 = 40px. Total space taken horizontally = 230px + 40px = 270px.

3. Final Answer:

   270px plus margin -> Option C

4. Quick Check:

   Total width = content + padding + border + margin [OK]

Hint: Add padding and border twice, margin outside [OK]

Common Mistakes:

• Forgetting to double padding and border for both sides
• Including margin inside width
• Adding margin only once

3. What is the total height of this element including padding and border?

height: 150px; padding: 15px 10px; border: 3px solid;

medium

A. 186px

B. 150px

C. 176px

D. 181px

Solution

1. Step 1: Calculate vertical padding and border

   Padding top+bottom = 15px * 2 = 30px. Border top+bottom = 3px * 2 = 6px.

2. Step 2: Add padding and border to content height

   Total height = content height (150px) + padding (30px) + border (6px) = 186px.

3. Final Answer:

   186px -> Option A

4. Quick Check:

   Total height = content + padding + border [OK]

Hint: Add vertical padding and border twice to height [OK]

Common Mistakes:

• Using horizontal padding values for vertical calculation
• Forgetting to double padding and border
• Ignoring border size

4. This CSS code is meant to create a box 300px wide including padding and border. What is wrong?

width: 300px; padding: 20px; border: 10px solid;

medium

A. The box will be wider than 300px

B. The box will be exactly 300px wide

C. Padding and border are ignored in width

D. The box will be narrower than 300px

Solution

1. Step 1: Calculate total width with padding and border

   Content width is 300px, but padding adds 20px*2=40px and border adds 10px*2=20px, total 360px.

2. Step 2: Understand box-sizing default

   By default, width sets content box only, so padding and border add outside, making box wider than 300px.

3. Final Answer:

   The box will be wider than 300px -> Option A

4. Quick Check:

   Default box-sizing excludes padding and border [OK]

Hint: Width excludes padding and border unless box-sizing set [OK]

Common Mistakes:

• Assuming width includes padding and border by default
• Ignoring box-sizing property
• Not doubling padding and border

5. You want a box with total width 400px including padding and border. Padding is 15px and border is 5px. What should the CSS width be if box-sizing: content-box;?

hard

A. 430px

B. 400px

C. 350px

D. 360px

Solution

1. Step 1: Calculate total padding and border width

   Padding left+right = 15px * 2 = 30px. Border left+right = 5px * 2 = 10px. Total extra = 40px.

2. Step 2: Subtract padding and border from total width

   Desired total width = 400px. Content width = 400px - 40px = 360px.

3. Step 3: Confirm CSS width value

   Set width: 360px; to get total 400px box size with content-box sizing.

4. Final Answer:

   360px -> Option D

5. Quick Check:

   width = total - (padding + border) [OK]

Hint: Subtract padding and border from total width [OK]

Common Mistakes:

• Adding padding and border instead of subtracting
• Forgetting to double padding and border
• Confusing content-box with border-box