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manish1803manish1803/nextjs-fullstack-skills/skills/01-frontend-engineering/responsive-mobile-first/SKILL.md

responsive-mobile-first

Skill2 starsChanged 4 months agoMITView on GitHub

Design and implement responsive, mobile-first layouts using fluid typography, container queries, and correct Tailwind/CSS breakpoint strategy. Use whenever the user builds any UI layout, mentions "responsive", "mobile", "breakpoints", asks why a layout breaks on small screens, or is building anything user-facing without specifying device — always assume mobile-first unless told otherwise.

The file

We split this skill into the rules it gives an agent

6 rules. About 0 are common, 2 are distinctive, and 4 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈2

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 4

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Default posture: build for the smallest viewport first, then progressively enhance upward.

    line 8
  2. Very specific:

    Don't skip straight to lg: for something that also needs to look right at md: — test the in-between.

    line 13
  3. Very specific:

    Fluid typography: use clamp() (text-[clamp(1.5rem,4vw,2.5rem)] or a Tailwind plugin) for hero/display text instead of jumping abruptly at …

    line 16
  4. Very specific:

    Layout primitives: prefer flex/grid with flex-wrap, grid-cols-1 md:grid-cols-2 lg:grid-cols-3 over fixed pixel widths.

    line 17
  5. Very specific:

    Images/media: always constrain with max-w-full h-auto or next/image with sizes set correctly per breakpoint to avoid oversized downloads on …

    line 21
  6. Distinctive:

    No horizontal scroll at any breakpoint unless explicitly intentional (e.g.

    line 26

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Responsive & Mobile-First Design Skill

Default posture: build for the smallest viewport first, then progressively enhance upward. Never build desktop-first and retrofit mobile with overrides.

Breakpoint strategy (Tailwind defaults, extend only if justified)

sm 640px · md 768px · lg 1024px · xl 1280px · 2xl 1536px

  • Base (no prefix) styles = mobile (< 640px). Add md:/lg: to layer in more complex layouts as space grows.
  • Don't skip straight to lg: for something that also needs to look right at md: — test the in-between.

Core patterns

  • Fluid typography: use clamp() (text-[clamp(1.5rem,4vw,2.5rem)] or a Tailwind plugin) for hero/display text instead of jumping abruptly at breakpoints.
  • Layout primitives: prefer flex/grid with flex-wrap, grid-cols-1 md:grid-cols-2 lg:grid-cols-3 over fixed pixel widths.
  • Container queries (@container) for components that must adapt to their parent's width, not the viewport — e.g. a Card that appears both in a narrow sidebar and a wide main column.
  • Touch targets: minimum 44×44px tappable area on interactive elements for mobile; increase spacing between adjacent tap targets.
  • Navigation: collapse to a drawer/sheet below md, not a squeezed horizontal nav.
  • Images/media: always constrain with max-w-full h-auto or next/image with sizes set correctly per breakpoint to avoid oversized downloads on mobile.

Testing checklist before calling a layout done

  1. 375px (small phone), 768px (tablet), 1024px (small laptop), 1440px+ (desktop)
  2. Long content (long names, long numbers) doesn't break the layout at any width
  3. No horizontal scroll at any breakpoint unless explicitly intentional (e.g. a carousel)
  4. Touch targets ≥44px on mobile; hover-only interactions have a tap/focus equivalent

Anti-patterns to flag

  • Hardcoded width: 800px on a container instead of max-w-3xl w-full
  • Desktop nav hidden with hidden md:block but no mobile alternative provided
  • Font sizes fixed at desktop scale, causing overflow/wrapping on mobile
  • Media queries scattered ad hoc instead of using the design system's breakpoint tokens

Example prompt this skill should trigger on

"Build a pricing page with 3 tiers — make sure it looks good on mobile too."

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