Row and column structure in Bootsrap - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Bootstrap Grid Rows

In Bootstrap, what is the main purpose of a .row class inside a container?

A It defines the width of the container to be fixed and centered.

B It adds padding around the container to create space outside the grid.

C It creates a horizontal group of columns and clears the floats to align columns properly.

D It styles text inside columns to be bold and centered.

💡 Hint

Think about how columns are arranged horizontally in Bootstrap.

The .row class groups columns horizontally and uses negative margins to offset the padding of columns, ensuring columns align correctly without extra space.

📝 Syntax

intermediate

Correct Column Class Usage

Which option correctly creates three equal-width columns inside a Bootstrap row for medium screens and above?

Bootsrap

<div class="container">
  <div class="row">
    <!-- Columns here -->
  </div>
</div>

A <div class="col-md-4">Column 1</div><div class="col-md-4">Column 2</div><div class="col-md-4">Column 3</div>

B <div class="col-3">Column 1</div><div class="col-3">Column 2</div><div class="col-3">Column 3</div>

C <div class="col-md-3">Column 1</div><div class="col-md-3">Column 2</div><div class="col-md-3">Column 3</div>

D <div class="col-md-6">Column 1</div><div class="col-md-6">Column 2</div><div class="col-md-6">Column 3</div>

💡 Hint

Bootstrap grid columns add up to 12 units per row.

Each column should take 4 units (4 + 4 + 4 = 12) to create three equal columns on medium screens and larger.

❓ layout

advanced

Responsive Column Behavior

Given this Bootstrap code, how will the columns behave on small (sm) and large (lg) screens?

A

B

C

D

A On small screens, four columns per row; on large screens, two columns per row.

B On small screens, columns take full width; on large screens, two columns per row.

C On all screen sizes, columns stack vertically one by one.

D On small screens, two columns per row; on large screens, four columns per row.

💡 Hint

Remember Bootstrap grid uses 12 units per row and classes define column width per breakpoint.

col-sm-6 means each column takes 6 units (half width) on small screens, so two columns fit per row. col-lg-3 means each column takes 3 units (quarter width) on large screens, so four columns fit per row.

❓ selector

advanced

CSS Selector for Bootstrap Columns

Which CSS selector correctly targets all Bootstrap columns inside a row regardless of their size classes?

A .container .col

B .row > [class*='col-']

C .row .col

D .row > .col-md-4

💡 Hint

Bootstrap column classes always start with 'col-' followed by breakpoint and number.

The selector .row > [class*='col-'] selects all direct children of .row whose class attribute contains 'col-', matching all column sizes.

❓ accessibility

expert

Improving Accessibility in Bootstrap Grid

Which practice best improves keyboard navigation and screen reader clarity in a Bootstrap grid layout?

A Add <code>role="region"</code> and <code>aria-label</code> to each <code>.row</code> to describe the section purpose.

B Add <code>tabindex="-1"</code> to all columns to prevent keyboard focus.

C Use only <code>div</code> elements without roles or labels to keep code simple.

D Use inline styles to highlight columns visually without ARIA attributes.

💡 Hint

Think about how screen readers identify page sections and how keyboard users navigate.

Adding role="region" and descriptive aria-label to rows helps screen readers understand the purpose of each section and improves keyboard navigation by defining landmarks.

Practice

1. What is the main purpose of a .row in Bootstrap's grid system?

easy

A. To add background colors to sections

B. To add padding around the entire page

C. To create buttons with consistent styles

D. To group columns horizontally and manage their layout

Solution

1. Step 1: Understand the role of .row

   The .row class in Bootstrap groups columns horizontally to create a structured layout.

2. Step 2: Differentiate from other classes

   Other classes like padding or buttons serve different purposes, not layout grouping.

3. Final Answer:

   To group columns horizontally and manage their layout -> Option D

4. Quick Check:

   Row groups columns [OK]

Hint: Rows always group columns horizontally [OK]

Common Mistakes:

• Thinking rows add padding or style
• Confusing rows with buttons or backgrounds
• Assuming rows create vertical stacks

2. Which of the following is the correct syntax to create a row with three equal columns in Bootstrap?

easy

A.

B.

C.

D.

Solution

1. Step 1: Identify correct Bootstrap column syntax

   Bootstrap uses col classes inside a row to create equal-width columns.

2. Step 2: Check each option

   uses col inside row, which creates three equal columns automatically.

3. Final Answer:

   <div class='row'><div class='col'></div><div class='col'></div><div class='col'></div></div> -> Option A

4. Quick Check:

   Use col inside row for equal columns [OK]

Hint: Use col inside row for equal columns [OK]

Common Mistakes:

• Using container instead of row for columns
• Using non-Bootstrap class names like column
• Using fixed column sizes unnecessarily

3. What will be the visual layout result of this code?

<div class='row'>
  <div class='col-6'>Left</div>
  <div class='col-6'>Right</div>
</div>

medium

A. Two columns side by side, each taking half the row width

B. Two columns stacked vertically, each taking full width

C. One column taking full width, the other hidden

D. Columns overlap each other in the same space

Solution

1. Step 1: Understand col-6 in Bootstrap grid

   Each col-6 takes 6 of 12 parts, so half the row width.

2. Step 2: Visualize the layout

   Two col-6 columns inside a row appear side by side, each half width.

3. Final Answer:

   Two columns side by side, each taking half the row width -> Option A

4. Quick Check:

   col-6 + col-6 = two halves side by side [OK]

Hint: Sum of column numbers should be 12 for full row width [OK]

Common Mistakes:

• Thinking columns stack vertically by default
• Assuming columns overlap without floats or flex
• Confusing col-6 with full width

4. Identify the error in this Bootstrap grid code:

<div class='row'>
  <div class='col-8'>Content</div>
  <div class='col-6'>Sidebar</div>
</div>

medium

A. Using col-8 and col-6 is invalid syntax

B. Missing .container wrapper around the row

C. The total column width exceeds 12, causing layout issues

D. The row class should be column

Solution

1. Step 1: Calculate total column widths

   col-8 + col-6 = 14, which is more than 12 grid units.

2. Step 2: Understand Bootstrap grid limits

   Bootstrap grid rows should have columns summing to 12 or less to avoid wrapping or overflow.

3. Final Answer:

   The total column width exceeds 12, causing layout issues -> Option C

4. Quick Check:

   Sum of columns > 12 breaks layout [OK]

Hint: Column widths in a row must sum to 12 or less [OK]

Common Mistakes:

• Ignoring total column width sum
• Thinking container is mandatory for rows
• Confusing class names like column instead of row

5. You want a layout with 4 columns where the first takes 3 parts, the second 3 parts, the third 4 parts, and the last 2 parts of the row width. Which Bootstrap classes correctly achieve this?

hard

A. col-4, col-3, col-3, col-2

B. col-3, col-3, col-4, col-2

C. col-3, col-3, col-3, col-3

D. col-2, col-3, col-4, col-3

Solution

1. Step 1: Check the sum of column widths

   3 + 3 + 4 + 2 = 12, which fits perfectly in Bootstrap's 12-grid system.

2. Step 2: Match the order of columns to the question

   The first column should be 3, second 3, third 4, and last 2, matching col-3, col-3, col-4, col-2 exactly.

3. Final Answer:

   col-3, col-3, col-4, col-2 -> Option B

4. Quick Check:

   Sum 12 and order match [OK]

Hint: Sum columns to 12 and keep order as needed [OK]

Common Mistakes:

• Choosing columns that sum more or less than 12
• Mixing column order
• Using equal columns when specific widths are needed