Mobile-first philosophy in Tailwind - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ selector

intermediate

Understanding Tailwind's Mobile-First Breakpoints

Which Tailwind CSS class applies styles only on screens wider than 768px (medium devices and up)?

A lg:text-center

B md:text-center

C text-center md:text-center

D text-center md:

💡 Hint

Tailwind uses prefixes like md: to apply styles from that breakpoint and up.

The md: prefix applies styles starting at the medium breakpoint (768px). Option B correctly uses md:text-center to center text only on medium screens and larger. Option B is invalid syntax. Option B applies text-center always and again at md, so not only at md. Option B applies styles at large screens (1024px) and up.

❓ layout

intermediate

Mobile-First Responsive Layout with Tailwind

Given this Tailwind HTML snippet, what will be the width of the div on a small screen (less than 640px)?

<div class="w-full sm:w-1/2 lg:w-1/4">Content</div>

Tailwind

<div class="w-full sm:w-1/2 lg:w-1/4">Content</div>

A 100% width

B 25% width

C 50% width

D 0 width (hidden)

💡 Hint

Tailwind applies styles without prefixes first, then overrides at breakpoints.

The class w-full applies 100% width by default (mobile first). The sm:w-1/2 applies 50% width starting at 640px, and lg:w-1/4 applies 25% width starting at 1024px. On screens smaller than 640px, only w-full applies.

❓ rendering

advanced

Visual Result of Mobile-First Flexbox Layout

What will you see on a mobile screen (less than 640px wide) for this Tailwind HTML?

<div class="flex flex-col sm:flex-row">
  <div class="p-4 bg-blue-500">Box 1</div>
  <div class="p-4 bg-green-500">Box 2</div>
</div>

Tailwind

<div class="flex flex-col sm:flex-row">
  <div class="p-4 bg-blue-500">Box 1</div>
  <div class="p-4 bg-green-500">Box 2</div>
</div>

A Boxes hidden

B Boxes side by side horizontally, blue box left, green box right

C Boxes overlap each other

D Boxes stacked vertically, blue box on top, green box below

💡 Hint

The flex-col class stacks items vertically, and sm:flex-row changes layout on larger screens.

On mobile screens, flex-col applies, stacking boxes vertically. The sm:flex-row applies only on screens 640px and wider, changing layout to horizontal. So on mobile, boxes appear stacked with Box 1 on top.

❓ accessibility

advanced

Accessibility Considerations in Mobile-First Design

Which practice best improves accessibility for a mobile-first navigation menu using Tailwind CSS?

A Use semantic <nav> element with aria-label and ensure keyboard focus styles are visible

B Hide navigation on mobile using display:none without alternative access

C Use only color changes to indicate active menu items without focus styles

D Use <div> elements for navigation without roles or labels

💡 Hint

Accessibility means everyone can use your site, including keyboard users and screen readers.

Using semantic

with an aria-label helps screen readers understand the navigation. Visible keyboard focus styles help users who navigate with keyboards. Hiding navigation without alternatives or using only color changes harms accessibility. Using

without roles or labels provides no semantic meaning.

🧠 Conceptual

expert

Why Mobile-First CSS is Preferred in Tailwind

Why does Tailwind CSS use a mobile-first approach for its responsive utilities?

A Because mobile-first CSS disables styles on desktop by default

B Because desktop styles override mobile styles by default, making desktop easier to style

C Because mobile-first CSS loads smaller styles first, improving performance on mobile devices

D Because mobile-first CSS requires writing more code, which is better for maintainability

💡 Hint

Think about what devices usually have slower connections and smaller screens.

Mobile-first CSS applies base styles for small screens first, then adds overrides for larger screens. This means mobile devices load only essential styles initially, improving performance. Desktop styles override mobile styles as needed. Options B, C, and D are incorrect or misleading.