Mobile Design — Always Include

Every UI task must produce mobile specifications. Designs without mobile coverage are incomplete. Apply these rules regardless of whether the user mentions mobile.

Layout & Breakpoints

Breakpoint	Width	Layout
Mobile S	320px	Single column, full-width blocks
Mobile L	375px–428px	Single column, standard mobile
Tablet	768px	2-column or adaptive single
Desktop	1280px+	Full multi-column

Default breakpoints (adapt to project's system): sm: 640px · md: 768px · lg: 1024px · xl: 1280px

Mobile-first rule: design the 375px layout first, then expand. Never design desktop-first and shrink.

Navigation — Mobile vs Desktop

Pattern	Mobile	Desktop
Primary nav	Bottom tab bar (≤ 5 items) or hamburger drawer	Top horizontal nav or sidebar
Secondary nav	Drawer, bottom sheet, or accordion	Sidebar or breadcrumb
Search	Full-screen overlay	Inline search bar
Modals	Bottom sheet (full or partial)	Centered modal

Content Layout Rules by Breakpoint

• Cards: full-width at mobile; 2-up at tablet; 3–4-up at desktop
• Tables: horizontal scroll or card-list transformation at mobile — never squeeze columns
• Forms: single-column at mobile; max 2-column at tablet/desktop for related fields
• Sidebars: collapse to drawer or hide at mobile; show at ≥ 768px

Typography — Mobile Adjustments

Element	Desktop	Mobile
H1	36–48px	24–30px
H2	24–30px	20–24px
Body	16px	16px (never below 14px)
Caption	14px	13–14px
Line height	1.5	1.5–1.6

Spacing — Mobile Adjustments

• Page horizontal padding: 16px mobile · 24px tablet · 32px+ desktop
• Section vertical spacing: 40–48px mobile · 64–80px desktop
• Component internal padding: reduce by 25–33% vs desktop
• Gap between stacked elements: 12–16px mobile · 16–24px desktop

Touch & Interaction Rules

• Minimum touch target: 44×44px (Apple HIG) / 48×48dp (Material)
• Tap feedback: every interactive element must have an active/pressed state
• Hover-only interactions: must have a touch-accessible alternative
• Input zoom prevention: font-size ≥ 16px on all form inputs (prevents iOS auto-zoom)
• Keyboard avoidance: sticky footers and fixed CTAs must account for soft keyboard height
• Swipe gestures: document which gestures are available; never the only way to access a feature

Component Responsive Behavior Summary

Component	Mobile behavior
Button group	Stack vertically; full-width primary button
Data table	Horizontal scroll or transform to card list
Tabs	Horizontal scroll if > 4; consider bottom nav
Dropdown/Select	Native OS picker preferred
Toast/Snackbar	Bottom of screen, above nav bar
Pagination	Infinite scroll or "Load more" preferred

Mobile-First Coding Convention

Instruct the frontend-developer to write mobile-first CSS:

/* Base = mobile */
.card { padding: 16px; flex-direction: column; }

/* Expand up */
@media (min-width: 768px) {
  .card { padding: 24px; flex-direction: row; }
}

Never write desktop-first and override with max-width queries.