Custom color themes in Bootsrap - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to apply a custom primary color using Bootstrap utility classes.

Bootsrap

<button class="btn btn-[1]">Click me</button>

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

Asecondary

Bdanger

Cprimary

Dsuccess

Attempts:

3 left

💡 Hint

Common Mistakes

Using a color class that does not exist like btn-main

Forgetting to add the btn class before the color class

The btn-primary class applies the primary color to the button.

2fill in blank

medium

Complete the code to define a CSS variable for a custom color in Bootstrap.

Bootsrap

:root { --bs-[1]: #ff6347; }

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

Aprimary

Bsecondary

Csuccess

Ddanger

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that does not start with --bs-

Using a color name that is not recognized by Bootstrap

The --bs-primary CSS variable sets the primary color in Bootstrap.

3fill in blank

hard

Fix the error in the code to correctly apply a custom background color using Bootstrap variables.

Bootsrap

.custom-bg { background-color: var(--bs-[1]); }

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

Abackground

Bprimary

Ccolor

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect variable names like --bs-background or --bs-color

Forgetting to use the var() function

The correct CSS variable for the primary background color is --bs-primary.

4fill in blank

hard

Fill both blanks to create a CSS rule that changes the primary color and applies it to text.

Bootsrap

:root { --bs-[1]: #4caf50; } .text-[2] { color: var(--bs-primary); }

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

Aprimary

Bsecondary

Csuccess

Ddanger

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing different color names in the two blanks

Using a color name that does not match the CSS variable

Setting --bs-primary changes the primary color, and .text-primary applies it to text.

5fill in blank

hard

Fill all three blanks to create a CSS custom theme with primary color, background, and border color.

Bootsrap

:root { --bs-[1]: #007bff; --bs-[2]-bg-subtle: #e9f5ff; --bs-[3]-border-subtle: #80bdff; }

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

Aprimary

Bsecondary

Attempts:

3 left

💡 Hint

Common Mistakes

Using different color names like secondary for the blanks

Omitting the '-subtle' suffix

The primary color is set with --bs-primary, background with --bs-primary-bg-subtle, and border with --bs-primary-border-subtle.

Practice

1. What is the main purpose of creating a custom color theme in Bootstrap?

easy

A. To disable Bootstrap's grid system

B. To add new Bootstrap components

C. To change Bootstrap's default colors to match your brand

D. To increase the font size globally

Solution

1. Step 1: Understand Bootstrap's default colors

   Bootstrap comes with preset colors that style buttons, backgrounds, and text.

2. Step 2: Purpose of custom color themes

   Custom color themes let you replace these default colors with your own brand colors for consistency.

3. Final Answer:

   To change Bootstrap's default colors to match your brand -> Option C

4. Quick Check:

   Custom colors = brand matching [OK]

Hint: Custom themes change colors to fit your brand [OK]

Common Mistakes:

• Thinking custom themes add new components
• Confusing color themes with layout changes
• Assuming it disables Bootstrap features

2. Which CSS selector is commonly used to define custom color variables for Bootstrap themes?

easy

A. html

B. .custom-theme

C. body

D. :root

Solution

1. Step 1: Identify where CSS variables are defined

   CSS variables for themes are usually set globally for easy access.

2. Step 2: Recognize the :root selector

   :root targets the highest-level element in the document, perfect for global variables.

3. Final Answer:

   :root -> Option D

4. Quick Check:

   Global CSS variables = :root [OK]

Hint: Use :root for global CSS variables [OK]

Common Mistakes:

• Using class selectors instead of :root
• Defining variables inside body or html only
• Confusing :root with other pseudo-classes

3. Given this CSS snippet, what color will the primary button have?

:root { --bs-primary: #ff5733; }
.btn-primary { background-color: var(--bs-primary); }

medium

A. #ff5733 (a bright orange-red)

B. #007bff (Bootstrap default blue)

C. Transparent

D. Black

Solution

1. Step 1: Check the CSS variable definition

   --bs-primary is set to #ff5733 in :root, overriding default.

2. Step 2: Understand button background color

   .btn-primary uses var(--bs-primary), so it uses #ff5733 as background.

3. Final Answer:

   #ff5733 (a bright orange-red) -> Option A

4. Quick Check:

   Button color = var(--bs-primary) = #ff5733 [OK]

Hint: Button uses var(--bs-primary) color [OK]

Common Mistakes:

• Assuming default blue color remains
• Ignoring CSS variable override
• Confusing variable name with value

4. What is wrong with this CSS if the custom primary color does not apply?

:root {
  --bs-primary: #28a745
}
.btn-primary {
  background-color: var(--bs-primary);
}

medium

A. Missing semicolon after color value in :root

B. Wrong variable name used in .btn-primary

C. CSS variables cannot be used in Bootstrap

D. The color code #28a745 is invalid

Solution

1. Step 1: Check CSS syntax in :root

   CSS declarations should end with a semicolon after each property value; missing after #28a745.

2. Step 2: Effect of missing semicolon

   Without semicolon, CSS parsing can break (especially with additional properties), causing the variable to be ignored.

3. Final Answer:

   Missing semicolon after color value in :root -> Option A

4. Quick Check:

   CSS syntax error = missing semicolon [OK]

Hint: Always end CSS declarations with semicolon [OK]

Common Mistakes:

• Assuming variable name is wrong
• Thinking CSS variables don't work in Bootstrap
• Believing color code is invalid

5. You want to create a dark theme by changing Bootstrap's background and text colors using CSS variables. Which code snippet correctly sets a dark background and light text for the whole page?

hard

A. html { --bs-body-bg: black; --bs-body-color: white; } .container { background-color: var(--bs-body-bg); color: var(--bs-body-color); }

B. :root { --bs-body-bg: #000000; --bs-body-color: #ffffff; } body { background-color: var(--bs-body-bg); color: var(--bs-body-color); }

C. :root { background-color: #000000; color: #ffffff; }

D. body { --bs-body-bg: #000000; --bs-body-color: #ffffff; }

Solution

1. Step 1: Define CSS variables globally

   Use :root to set --bs-body-bg and --bs-body-color for global theme colors.

2. Step 2: Apply variables to body styles

   Set body's background-color and color using the CSS variables for consistent theme.

3. Step 3: Check other options

   Defining variables on html but applying only to .container limits the theme to containers; defining variables on body without applying them to styles shows no visible change; setting colors directly on :root bypasses CSS variables.

4. Final Answer:

   :root { --bs-body-bg: #000000; --bs-body-color: #ffffff; } body { background-color: var(--bs-body-bg); color: var(--bs-body-color); } -> Option B

5. Quick Check:

   Global variables + body styles = dark theme [OK]

Hint: Set variables in :root and apply on body [OK]

Common Mistakes:

• Defining variables but not applying them
• Setting colors directly without variables
• Applying variables only to container, not whole page