/* IMPORTANT: Always include rem in fluid typography */
/* This ensures user font preferences are respected */

/* ❌ WRONG: Viewport-only ignores user preferences */
font-size: 5vw;

/* ✅ CORRECT: Include rem to respect user settings */
font-size: clamp(1rem, 0.5rem + 2vw, 2rem);

/* User zooming must still work */
@media (min-width: 768px) {
  /* Use em/rem, not px, for breakpoints in ideal world */
  /* (browsers still use px, but consider user zoom) */
}

/* ❌ NEVER: Use only viewport units for text */
.title {
  font-size: 5vw; /* Ignores user font preferences! */
}

/* ❌ NEVER: Use cqw/cqh (use cqi/cqb instead) */
.card {
  padding: 5cqw; /* cqw = container width, not logical */
}
/* ✅ CORRECT: Use logical units */
.card {
  padding: 5cqi; /* Container inline = logical direction */
}

/* ❌ NEVER: Container queries without container-type */
@container (min-width: 400px) {
  /* Won't work without container-type on parent! */
}

/* ❌ NEVER: Desktop-first media queries */
.element {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}
@media (max-width: 768px) {
  .element {
    grid-template-columns: 1fr; /* Overriding = more CSS */
  }
}

/* ❌ NEVER: Fixed pixel breakpoints for text */
@media (min-width: 768px) {
  body { font-size: 18px; } /* Use rem! */
}

/* ❌ NEVER: Over-nesting container queries */
@container a {
  @container b {
    @container c {
      /* Too complex, reconsider architecture */
    }
  }
}

// WRONG: Inconsistent animation values, no reduced-motion support
<motion.div
  initial={{ opacity: 0, y: 50, scale: 0.8 }}
  animate={{ opacity: 1, y: 0, scale: 1 }}
  transition={{ duration: 0.7, ease: "easeInOut" }}
>
  {/* Different values everywhere, no consistency */}
</motion.div>

// lib/animations.ts — Single source of truth
export const fadeInUp = {
  initial: { opacity: 0, y: 20 },
  animate: { opacity: 1, y: 0 },
  exit: { opacity: 0, y: -10 },
  transition: { type: 'spring', stiffness: 300, damping: 30 },
};

export const staggerContainer = {
  animate: { transition: { staggerChildren: 0.05 } },
};

export const staggerItem = {
  initial: { opacity: 0, y: 10 },
  animate: { opacity: 1, y: 0 },
};

// Usage with AnimatePresence for exit animations
import { motion, AnimatePresence } from 'motion/react';
import { staggerContainer, staggerItem, fadeInUp } from '@/lib/animations';

function AnimatedList({ items }: { items: Item[] }) {
  return (
    <AnimatePresence mode="wait">
      <motion.ul variants={staggerContainer} initial="initial" animate="animate">
        {items.map((item) => (
          <motion.li key={item.id} variants={staggerItem} layout>
            {item.name}
          </motion.li>
        ))}
      </motion.ul>
    </AnimatePresence>
  );
}

// React Router with View Transitions
import { Link, useViewTransitionState } from 'react-router';

function ProductCard({ product }: { product: Product }) {
  const isTransitioning = useViewTransitionState(`/products/${product.id}`);
  return (
    <Link to={`/products/${product.id}`} viewTransition>
      <img
        src={product.image}
        alt={product.name}
        style={{
          viewTransitionName: isTransitioning ? 'product-image' : undefined,
        }}
      />
    </Link>
  );
}

// WRONG: Scroll listeners run on main thread, cause jank
window.addEventListener('scroll', () => {
  const progress = window.scrollY / document.body.scrollHeight;
  progressBar.style.width = `${progress * 100}%`; // Layout thrashing!
  parallaxElement.style.transform = `translateY(${window.scrollY * 0.5}px)`;
});

/* Reading progress bar — zero JavaScript */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--color-primary);
  transform-origin: left;
  animation: grow-progress linear;
  animation-timeline: scroll(root block);
}

@keyframes grow-progress {
  from { transform: scaleX(0); }
  to { transform: scaleX(1); }
}

/* Reveal on scroll — element enters viewport */
.reveal-on-scroll {
  animation: fade-in-up linear both;
  animation-timeline: view();
  animation-range: entry 0% entry 100%;
}

@keyframes fade-in-up {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Parallax section */
.parallax-bg {
  animation: parallax-shift linear;
  animation-timeline: scroll(root block);
}

@keyframes parallax-shift {
  from { transform: translateY(-20%); }
  to { transform: translateY(20%); }
}

/* Feature detection — fallback for unsupported browsers */
@supports (animation-timeline: view()) {
  .reveal-on-scroll {
    animation: fade-in-up linear both;
    animation-timeline: view();
    animation-range: entry 0% entry 100%;
  }
}

/* Fallback: IntersectionObserver in JavaScript */
@supports not (animation-timeline: view()) {
  .reveal-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.5s, transform 0.5s;
  }
  .reveal-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Define a query container */
.card-container {
  container-type: inline-size;
  container-name: card;
}

/* Style based on container width */
@container card (min-width: 400px) {
  .card {
    display: grid;
    grid-template-columns: 200px 1fr;
  }
}

@container card (max-width: 399px) {
  .card {
    display: flex;
    flex-direction: column;
  }
}

/* Use cqi (container query inline) over cqw */
.card-title {
  /* 5% of container's inline size */
  font-size: clamp(1rem, 5cqi, 2rem);
}

.card-content {
  /* Responsive padding based on container */
  padding: 2cqi;
}

/* cqb for block dimension (height-aware containers) */
.sidebar-item {
  height: 10cqb;
}

/* Accessible fluid typography */
:root {
  /* Base font respects user preferences (rem) */
  --font-size-base: 1rem;

  /* Fluid scale with min/max bounds */
  --font-size-sm: clamp(0.875rem, 0.8rem + 0.25vw, 1rem);
  --font-size-md: clamp(1rem, 0.9rem + 0.5vw, 1.25rem);
  --font-size-lg: clamp(1.25rem, 1rem + 1vw, 2rem);
  --font-size-xl: clamp(1.5rem, 1rem + 2vw, 3rem);
  --font-size-2xl: clamp(2rem, 1rem + 3vw, 4rem);
}

h1 { font-size: var(--font-size-2xl); }
h2 { font-size: var(--font-size-xl); }
h3 { font-size: var(--font-size-lg); }
p { font-size: var(--font-size-md); }
small { font-size: var(--font-size-sm); }

/* For component-scoped fluid text */
.widget {
  container-type: inline-size;
}

.widget-title {
  /* Fluid within container, respecting user rem */
  font-size: clamp(1rem, 0.5rem + 5cqi, 2rem);
}

.widget-body {
  font-size: clamp(0.875rem, 0.5rem + 3cqi, 1.125rem);
}

/* Mobile-first: start small, add complexity */
.layout {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

/* Tablet and up */
@media (min-width: 768px) {
  .layout {
    flex-direction: row;
  }
}

/* Desktop */
@media (min-width: 1024px) {
  .layout {
    max-width: 1200px;
    margin-inline: auto;
  }
}

/* Auto-fit grid (fills available space) */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

/* Auto-fill grid (maintains minimum columns) */
.icon-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 1rem;
}

/* Subgrid for nested alignment */
.card {
  display: grid;
  grid-template-rows: subgrid;
  grid-row: span 3;
}

/* Query based on scroll state */
.scroll-container {
  container-type: scroll-state;
  container-name: scroller;
}

@container scroller scroll-state(scrollable: top) {
  .scroll-indicator-top {
    opacity: 0;
  }
}

@container scroller scroll-state(scrollable: bottom) {
  .scroll-indicator-bottom {
    opacity: 0;
  }
}

// WRONG: App crashes when offline
// No service worker fallback, no install prompt handling
// Users get browser error page instead of offline experience

// useOnlineStatus hook
export function useOnlineStatus() {
  const [isOnline, setIsOnline] = useState(navigator.onLine);

  useEffect(() => {
    const handleOnline = () => setIsOnline(true);
    const handleOffline = () => setIsOnline(false);
    window.addEventListener('online', handleOnline);
    window.addEventListener('offline', handleOffline);
    return () => {
      window.removeEventListener('online', handleOnline);
      window.removeEventListener('offline', handleOffline);
    };
  }, []);

  return isOnline;
}

// Install prompt hook
interface BeforeInstallPromptEvent extends Event {
  prompt: () => Promise<void>;
  userChoice: Promise<{ outcome: 'accepted' | 'dismissed' }>;
}

export function useInstallPrompt() {
  const [installPrompt, setInstallPrompt] = useState<BeforeInstallPromptEvent | null>(null);
  const [isInstalled, setIsInstalled] = useState(false);

  useEffect(() => {
    const handler = (e: BeforeInstallPromptEvent) => {
      e.preventDefault();
      setInstallPrompt(e);
    };
    window.addEventListener('beforeinstallprompt', handler as EventListener);
    if (window.matchMedia('(display-mode: standalone)').matches) setIsInstalled(true);
    return () => window.removeEventListener('beforeinstallprompt', handler as EventListener);
  }, []);

  const promptInstall = async () => {
    if (!installPrompt) return false;
    await installPrompt.prompt();
    const { outcome } = await installPrompt.userChoice;
    setInstallPrompt(null);
    if (outcome === 'accepted') { setIsInstalled(true); return true; }
    return false;
  };

  return { canInstall: !!installPrompt, isInstalled, promptInstall };
}

// sw.js
import { BackgroundSyncPlugin } from 'workbox-background-sync';
import { registerRoute } from 'workbox-routing';
import { NetworkOnly } from 'workbox-strategies';

registerRoute(
  /\/api\/forms/,
  new NetworkOnly({
    plugins: [
      new BackgroundSyncPlugin('formQueue', {
        maxRetentionTime: 24 * 60, // 24 hours
      }),
    ],
  }),
  'POST'
);

// WRONG: No skipWaiting means users stuck on old version
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open('v1').then((cache) =>
      cache.addAll(['/index.html', '/app.js', '/style.css'])
    )
  );
});
// Missing: skipWaiting, clientsClaim, no update prompt

import { registerRoute } from 'workbox-routing';
import { CacheFirst, NetworkFirst, StaleWhileRevalidate } from 'workbox-strategies';
import { ExpirationPlugin } from 'workbox-expiration';
import { CacheableResponsePlugin } from 'workbox-cacheable-response';

// Static assets: CacheFirst (hashed filenames = safe to cache long)
registerRoute(
  /\.(?:js|css|woff2)$/,
  new CacheFirst({
    cacheName: 'static-v1',
    plugins: [
      new ExpirationPlugin({ maxEntries: 100, maxAgeSeconds: 365 * 24 * 60 * 60 }),
    ],
  })
);

// API calls: NetworkFirst (fresh data preferred, cached fallback)
registerRoute(
  /\/api\//,
  new NetworkFirst({
    cacheName: 'api-cache',
    networkTimeoutSeconds: 10,
    plugins: [new CacheableResponsePlugin({ statuses: [0, 200] })],
  })
);

// Avatars/images: StaleWhileRevalidate (show cached, update in background)
registerRoute(
  /\/avatars\//,
  new StaleWhileRevalidate({ cacheName: 'avatars' })
);

// vite.config.ts
import { VitePWA } from 'vite-plugin-pwa';

export default defineConfig({
  plugins: [
    VitePWA({
      registerType: 'autoUpdate',
      workbox: {
        globPatterns: ['**/*.{js,css,html,ico,png,svg,woff2}'],
        runtimeCaching: [
          { urlPattern: /^https:\/\/api\./, handler: 'NetworkFirst' },
        ],
      },
      manifest: {
        name: 'My PWA App',
        short_name: 'MyPWA',
        theme_color: '#4f46e5',
        icons: [
          { src: '/icon-192.png', sizes: '192x192', type: 'image/png' },
          { src: '/icon-512.png', sizes: '512x512', type: 'image/png' },
        ],
      },
    }),
  ],
});

import { cn } from '@/lib/utils';

interface CardProps {
  title: string;
  description: string;
  image: string;
}

export function ResponsiveCard({ title, description, image }: CardProps) {
  return (
    <div className="@container">
      <article className={cn(
        "flex flex-col gap-4",
        "@md:flex-row @md:gap-6" // Container query breakpoints
      )}>
        <img
          src={image}
          alt=""
          className="w-full @md:w-48 aspect-video object-cover rounded-lg"
        />
        <div className="flex flex-col gap-2">
          <h3 className="text-[clamp(1rem,0.5rem+3cqi,1.5rem)] font-semibold">
            {title}
          </h3>
          <p className="text-[clamp(0.875rem,0.5rem+2cqi,1rem)] text-muted-foreground">
            {description}
          </p>
        </div>
      </article>
    </div>
  );
}

// @container enables container query variants (@sm, @md, @lg, etc.)
<div className="@container">
  <div className="flex flex-col @lg:flex-row @xl:gap-8">
    <div className="@sm:p-4 @md:p-6 @lg:p-8">
      Content adapts to container
    </div>
  </div>
</div>

import { useRef, useState, useEffect } from 'react';

function useContainerQuery(breakpoint: number) {
  const ref = useRef<HTMLDivElement>(null);
  const [isAbove, setIsAbove] = useState(false);

  useEffect(() => {
    const element = ref.current;
    if (!element) return;

    const observer = new ResizeObserver(([entry]) => {
      setIsAbove(entry.contentRect.width >= breakpoint);
    });

    observer.observe(element);
    return () => observer.disconnect();
  }, [breakpoint]);

  return [ref, isAbove] as const;
}

// Usage
function AdaptiveCard() {
  const [containerRef, isWide] = useContainerQuery(400);

  return (
    <div ref={containerRef}>
      {isWide ? <HorizontalLayout /> : <VerticalLayout />}
    </div>
  );
}

function ResponsiveImage({
  src,
  alt,
  sizes = "(max-width: 640px) 100vw, (max-width: 1024px) 50vw, 33vw"
}: {
  src: string;
  alt: string;
  sizes?: string;
}) {
  return (
    <picture>
      {/* Art direction with different crops */}
      <source
        media="(max-width: 640px)"
        srcSet={`${src}?w=640&aspect=1:1`}
      />
      <source
        media="(max-width: 1024px)"
        srcSet={`${src}?w=800&aspect=4:3`}
      />
      <img
        src={`${src}?w=1200`}
        alt={alt}
        sizes={sizes}
        loading="lazy"
        decoding="async"
        className="w-full h-auto object-cover"
      />
    </picture>
  );
}

/* Size queries (width/height) */
container-type: inline-size;  /* Query inline dimension */
container-type: size;         /* Query both dimensions */
container-type: normal;       /* No containment (default) */

/* Named container */
container-name: card;

/* Shorthand */
container: card / inline-size;

/* Width queries */
@container (min-width: 400px) { }
@container (max-width: 399px) { }
@container (width > 400px) { }
@container (400px <= width <= 800px) { }

/* Named container queries */
@container card (min-width: 400px) { }

/* Logical properties */
@container (min-inline-size: 400px) { }
@container (min-block-size: 300px) { }

/* Inline dimension (usually width) */
cqi  /* 1% of container inline size */

/* Block dimension (usually height) */
cqb  /* 1% of container block size */

/* Min/max of cqi and cqb */
cqmin
cqmax

/* Legacy (avoid - not logical) */
cqw  /* Container width */
cqh  /* Container height */

<!-- Enable container with @container -->
<div class="@container">
  <div class="flex flex-col @md:flex-row @lg:gap-8">
    <!-- Responsive to container, not viewport -->
  </div>
</div>

<!-- Named containers -->
<div class="@container/card">
  <div class="@lg/card:grid-cols-2">
    <!-- Queries the 'card' container -->
  </div>
</div>

/* app.css - Tailwind v4 CSS-first approach */
@import "tailwindcss";

@theme {
  /* Custom container breakpoints (optional) */
  --container-3xs: 16rem;
  --container-2xs: 18rem;
  --container-xs: 20rem;
  /* Default breakpoints: @sm (20rem), @md (28rem), @lg (32rem), etc. */
}

/* ✅ Use logical units */
.card-title {
  font-size: clamp(1rem, 5cqi, 2rem);
  padding: 2cqi;
}

/* ✅ Nest containers carefully */
.outer {
  container: outer / inline-size;
}
.inner {
  container: inner / inline-size;
}
@container inner (min-width: 200px) { }

/* ❌ Don't query non-container */
.no-container {
  /* No container-type set */
}
@container (min-width: 400px) {
  /* This won't work! */
}

@supports (container-type: inline-size) {
  .card-container {
    container-type: inline-size;
  }
}

/* Syntax: clamp(min, preferred, max) */
font-size: clamp(1rem, 0.5rem + 2vw, 2rem);

/* Breakdown:
   min: 1rem (16px at default)
   preferred: 0.5rem + 2vw (scales with viewport)
   max: 2rem (32px at default)
*/

:root {
  /* Always include rem to respect user preferences */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.375vw, 1rem);
  --text-base: clamp(1rem, 0.9rem + 0.5vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.625vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1rem + 1.25vw, 1.75rem);
  --text-2xl: clamp(1.5rem, 1rem + 2.5vw, 2.5rem);
  --text-3xl: clamp(1.875rem, 1rem + 4.375vw, 3.5rem);
  --text-4xl: clamp(2.25rem, 1rem + 6.25vw, 4.5rem);
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
p { font-size: var(--text-base); }
small { font-size: var(--text-sm); }

/* For component-scoped scaling */
.card {
  container-type: inline-size;
}

.card-title {
  /* Scales with card width, not viewport */
  font-size: clamp(1rem, 0.5rem + 5cqi, 1.75rem);
}

.card-body {
  font-size: clamp(0.875rem, 0.5rem + 3cqi, 1rem);
}

Target: 16px at 320px viewport → 24px at 1200px viewport

Formula:
preferred = min + (max - min) × (viewport - min-viewport) / (max-viewport - min-viewport)

Step 1: Convert to vw
  (24 - 16) / (1200 - 320) = 8 / 880 = 0.909% per px
  0.909 × 100 = 0.909vw

Step 2: Calculate rem offset
  At 320px: 16px = 1rem
  16 - (320 × 0.00909) = 16 - 2.91 = 13.09px ≈ 0.818rem

Result:
font-size: clamp(1rem, 0.818rem + 0.909vw, 1.5rem);

/* ❌ WRONG: Ignores user font preferences */
font-size: 5vw;

/* ❌ WRONG: Completely overrides user settings */
font-size: 16px;

/* ✅ CORRECT: Respects user preferences while scaling */
font-size: clamp(1rem, 0.5rem + 2vw, 2rem);

/* The rem portion ensures user's font-size preference
   is always a factor in the final size */

/* Tighter line-height for larger text */
h1 {
  font-size: clamp(2rem, 1rem + 5vw, 4rem);
  line-height: clamp(1.1, 1.4 - 0.2vw, 1.3);
}

p {
  font-size: clamp(1rem, 0.9rem + 0.5vw, 1.125rem);
  line-height: 1.6; /* Static is fine for body */
}