Mobile-first approach in CSS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the mobile-first approach in web design?

It means designing the website starting with the smallest screen (mobile) first, then adding styles for bigger screens like tablets and desktops.

beginner

Why is mobile-first approach important?

Because most people use phones to browse the web, so starting with mobile ensures the site works well on small screens and loads faster.

intermediate

How do you write a CSS media query for mobile-first design?

Start with base styles for mobile, then use @media (min-width: 768px) to add styles for larger screens.

beginner

What does min-width mean in a media query?

It means the styles inside the media query apply only if the screen is at least that wide, so bigger than or equal to that width.

beginner

Give an example of a simple mobile-first CSS snippet.

Base styles for mobile:
body { font-size: 1rem; }
Then for tablets and up:
@media (min-width: 768px) { body { font-size: 1.25rem; } }

What does the mobile-first approach focus on?

A Designing for small screens first

B Designing for desktop screens first

C Ignoring mobile devices

D Using only fixed widths

Mobile-first means starting design with small screens like phones before bigger screens.

Which CSS media query is used in mobile-first design to target larger screens?

A @media (max-width: 768px)

B @media (min-width: 768px)

C @media screen and (orientation: landscape)

D @media (max-height: 600px)

In mobile-first, we use min-width to add styles for screens wider than the mobile size.

Why start with mobile styles first?

A Because desktop users are fewer

B Mobile screens are bigger

C Mobile devices have faster internet

D To ensure good experience on small screens

Starting with mobile ensures the site works well on small screens where space is limited.

What happens if you use max-width instead of min-width in media queries for mobile-first?

A You target bigger screens first

B You target only landscape mode

C You target smaller screens first

D You target all screens

max-width targets screens smaller than or equal to the value, which is opposite of mobile-first.

Which unit is better for responsive font sizes in mobile-first CSS?

A rem

B pt

C px

D cm

rem units scale better with user settings and are preferred for responsive design.

Explain the mobile-first approach and why it is useful in web design.

Think about how most people use the web today.

Describe how to write a CSS media query for mobile-first design.

Remember, mobile-first means adding styles as screen size grows.

Practice

1. What does the mobile-first approach in CSS mean?

easy

A. Write all styles without using media queries

B. Start styling for small screens first, then add styles for larger screens

C. Start styling for desktop screens first, then add styles for smaller screens

D. Only style for mobile devices and ignore desktops

Solution

1. Step 1: Understand mobile-first approach

   Mobile-first means you write CSS targeting small screens first, like phones.

2. Step 2: Add styles for bigger screens

   Then you use media queries with min-width to add or change styles for tablets and desktops.

3. Final Answer:

   Start styling for small screens first, then add styles for larger screens -> Option B

4. Quick Check:

   Mobile-first = Start small, add bigger [OK]

Hint: Think: style phones first, then bigger screens [OK]

Common Mistakes:

• Confusing mobile-first with desktop-first
• Using max-width instead of min-width for bigger screens
• Ignoring media queries completely

2. Which CSS syntax correctly applies styles for screens wider than 600px in a mobile-first approach?

easy

A. @media (max-width: 600px) { ... }

B. @media (width: 600px) { ... }

C. @media screen and (min-width: 600px) { ... }

D. @media screen and (max-width: 600px) { ... }

Solution

1. Step 1: Identify mobile-first media query

   Mobile-first uses min-width to add styles for bigger screens.

2. Step 2: Choose correct syntax with media type

   Using @media screen and (min-width: 600px) targets screens wider than 600px correctly.

3. Final Answer:

   @media screen and (min-width: 600px) { ... } -> Option C

4. Quick Check:

   Mobile-first uses min-width with media type [OK]

Hint: Use min-width for bigger screens in mobile-first [OK]

Common Mistakes:

• Using max-width instead of min-width for bigger screens
• Using 'width' instead of 'min-width'
• Confusing min-width and max-width

3. Given this CSS, what background color will a 700px wide screen see?

body { background: white; }
@media (min-width: 600px) { body { background: blue; } }
@media (min-width: 800px) { body { background: green; } }

medium

A. Blue

B. White

C. Green

D. No background color

Solution

1. Step 1: Check base style

   Base background is white for all screen sizes.

2. Step 2: Check media queries for 700px width

   700px is >= 600px but < 800px, so blue applies, green does not.

3. Final Answer:

   Blue -> Option A

4. Quick Check:

   700px triggers min-width 600px but not 800px [OK]

Hint: Check which min-width media query matches screen size [OK]

Common Mistakes:

• Choosing green because 700 > 600 but ignoring 800px limit
• Choosing white ignoring media queries
• Confusing min-width with max-width

4. What is wrong with this mobile-first CSS snippet?

body { font-size: 14px; }
@media (max-width: 600px) { body { font-size: 16px; } }

medium

A. It uses max-width instead of min-width for bigger screens

B. No error, this is correct mobile-first CSS

C. The base font size should be larger than media query size

D. Media query should use min-width for mobile-first approach

Solution

1. Step 1: Identify media query type

   The snippet uses max-width: 600px, which targets small screens.

2. Step 2: Check mobile-first rule

   Mobile-first uses base styles for small screens and min-width for bigger screens, so this is reversed.

3. Final Answer:

   Media query should use min-width for mobile-first approach -> Option D

4. Quick Check:

   Mobile-first uses min-width, not max-width [OK]

Hint: Mobile-first uses min-width, max-width is desktop-first [OK]

Common Mistakes:

• Thinking max-width is correct for mobile-first
• Ignoring base styles importance
• Assuming no error in reversed media query

5. You want a button to have 100% width on phones and 200px width on screens wider than 768px. Which CSS correctly uses mobile-first approach?

hard

A. button { width: 100%; } @media (min-width: 768px) { button { width: 200px; } }

B. button { width: 200px; } @media (max-width: 768px) { button { width: 100%; } }

C. button { width: 100%; } @media (max-width: 768px) { button { width: 200px; } }

D. button { width: 200px; } @media (min-width: 768px) { button { width: 100%; } }

Solution

1. Step 1: Set base style for small screens

   Mobile-first means base style is for phones, so width 100% is base.

2. Step 2: Use min-width media query for bigger screens

   Use @media (min-width: 768px) to set width 200px for larger screens.

3. Final Answer:

   button { width: 100%; } @media (min-width: 768px) { button { width: 200px; } } -> Option A

4. Quick Check:

   Base small, min-width bigger = mobile-first [OK]

Hint: Base styles for mobile, min-width for bigger screens [OK]

Common Mistakes:

• Using max-width for bigger screens
• Setting desktop styles as base
• Reversing widths in media queries