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Lesson 23 / 26

Cheatsheet & Interview Q&A

Quick reference: key terms, media query syntax, breakpoints, and answers to common interview questions.

Responsive CSS quick reference

Essential patterns and syntax for responsive design.

/* Viewport meta tag (in HTML head) */
<meta name="viewport" content="width=device-width, initial-scale=1.0">

/* Mobile-first base */
.container { width: 100%; padding: 16px; }

/* Media query - tablet and up */
@media (min-width: 768px) { .container { padding: 24px; } }

/* Flexible units */
body { font-size: 1rem; } /* Use rem */
.box { width: 100%; max-width: 1200px; } /* Use % */

/* Clamp for smooth scaling */
h1 { font-size: clamp(1.5rem, 5vw, 3rem); }

/* Images responsive */
img { max-width: 100%; height: auto; }

/* Grid auto-fit */
.grid { grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }

Interview Q&A

Q: What is responsive design? A: Design that adapts to any screen size using flexible layouts, media queries, and flexible media.

Q: Why mobile-first? A: Simpler CSS, forces prioritization of content, and mobile is 50%+ of traffic.

Q: What's the difference between max-width and min-width media queries? A: min-width is mobile-first (build up), max-width is desktop-first (break down).

Q: How do you make images responsive? A: Use max-width: 100%, srcset for resolution, and for art direction.

Q: What's the minimum touch target size? A: 44x44px (Apple) or 48x48px (Android).

Viewport units cheatsheet

Quick reference for viewport and container-relative sizing.

/* Viewport units */
1vw = 1% of viewport width
1vh = 1% of viewport height
1vmin = 1% of smaller dimension
1vmax = 1% of larger dimension

/* Usage */
h1 { font-size: clamp(1.5rem, 5vw, 3rem); }
.hero { height: 100vh; }
.sidebar { width: 25vw; }

Interview tip: explain your approach

When asked about responsive design in an interview, explain the three pillars, your testing process, and real examples from your work.

Final quiz 1 of 8

Final quiz

Quick check: Which meta tag makes a page render at the device width on mobile?

  • charset
  • robots
  • viewport
  • description
Answer

viewport — The viewport meta tag stops mobile browsers from assuming a desktop width.

Final quiz 2 of 8

Final quiz

Quick check: In mobile-first CSS, which query do you mainly use?

  • max-width
  • orientation only
  • print
  • min-width
Answer

min-width — Base styles target mobile, and min-width layers on larger screens.

Final quiz 3 of 8

Final quiz

Quick check: What does clamp(1rem, 2.5vw, 2rem) do?

  • Scales smoothly between a minimum and maximum
  • Fixes the size at 2.5vw
  • Hides the element
  • Sets a media query
Answer

Scales smoothly between a minimum and maximum — The value follows the preferred size but never leaves the min and max.

Final quiz 4 of 8

Final quiz

Quick check: Which Grid pattern creates responsive columns without media queries?

  • grid-template-columns: 300px 300px
  • repeat(auto-fit, minmax(280px, 1fr))
  • float: left
  • display: inline
Answer

repeat(auto-fit, minmax(280px, 1fr)) — auto-fit with minmax wraps columns as space allows.

Final quiz 5 of 8

Final quiz

Quick check: What do container queries style components by?

  • The viewport only
  • The user agent
  • Their container's width
  • The page title
Answer

Their container's width — The same component adapts to wherever it is placed.

Final quiz 6 of 8

Final quiz

Quick check: Which attribute lets browsers pick an image size by screen?

  • alt
  • rel
  • lang
  • srcset
Answer

srcset — srcset with sizes lets the browser download the right resolution.

Final quiz 7 of 8

Final quiz

Quick check: What is a recommended minimum touch target size?

  • 44x44px
  • 16x16px
  • 10x10px
  • 24x12px
Answer

44x44px — Larger targets prevent mis-taps on touch screens.

Final quiz 8 of 8

Final quiz

Quick check: Which Core Web Vital measures unexpected layout movement?

  • LCP
  • CLS
  • INP
  • TTFB
Answer

CLS — CLS drops when images and ads reserve space with width, height or aspect-ratio.