/* China House Blog - Apple Design System CSS */
/* Mobile-first responsive design for chinahouse.blog */

/* ========================================
   CSS Reset & Base Styles
======================================== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
  color: #1D1D1F;
  background-color: #FFFFFF;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   Apple Color Palette Variables
======================================== */
:root {
  --primary-blue: #007AFF;
  --success-green: #34C759;
  --warning-orange: #FF9500;
  --text-primary: #1D1D1F;
  --text-secondary: #86868B;
  --background-primary: #FFFFFF;
  --background-secondary: #F2F2F7;
  --border-color: #D1D1D6;
  --hover-background: #E5E5EA;
  
  /* Spacing */
  --spacing-xs: 8px;
  --spacing-sm: 16px;
  --spacing-md: 24px;
  --spacing-lg: 32px;
  --spacing-xl: 48px;
  --spacing-xxl: 64px;
  
  /* Border radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  
  /* Typography */
  --font-size-sm: 14px;
  --font-size-base: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 20px;
  --font-size-2xl: 24px;
  --font-size-3xl: 32px;
  --font-size-4xl: 40px;
}

/* ========================================
   Typography
======================================== */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: var(--spacing-sm);
}

h1 {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
}

h2 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-sm);
  margin-top: var(--spacing-md);
}

h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-xs);
  margin-top: var(--spacing-md);
}

p {
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.lead {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-md);
}

small {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

/* ========================================
   Links & Buttons
======================================== */
a {
  color: var(--primary-blue);
  text-decoration: none;
  transition: all 0.2s ease;
}

a:hover, a:focus {
  color: var(--primary-blue);
  text-decoration: underline;
}

a:focus {
  outline: 2px solid var(--primary-blue);
  outline-offset: 2px;
}

.btn {
  display: inline-block;
  padding: var(--spacing-xs) var(--spacing-md);
  background-color: var(--primary-blue);
  color: white;
  border-radius: var(--radius-md);
  font-weight: 500;
  text-align: center;
  transition: all 0.2s ease;
  border: none;
  cursor: pointer;
  text-decoration: none;
  font-size: var(--font-size-base);
}

.btn:hover, .btn:focus {
  background-color: #0056CC;
  color: white;
  text-decoration: none;
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: var(--background-secondary);
  color: var(--text-primary);
}

.btn-secondary:hover, .btn-secondary:focus {
  background-color: var(--hover-background);
  color: var(--text-primary);
}

/* ========================================
   Layout & Grid
======================================== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-sm);
}

.section {
  padding: var(--spacing-sm) 0;
}

.section-sm {
  padding: var(--spacing-xs) 0;
}

.grid {
  display: grid;
  gap: var(--spacing-lg);
  grid-template-columns: 1fr;
}

/* ========================================
   Header & Navigation
======================================== */
header {
  background-color: var(--background-primary);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(20px);
  background-color: rgba(255, 255, 255, 0.8);
}

nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-sm) 0;
}

.logo {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
}

.logo:hover, .logo:focus {
  text-decoration: none;
  color: var(--primary-blue);
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--spacing-md);
}

.nav-menu a {
  color: var(--text-primary);
  font-weight: 500;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  transition: all 0.2s ease;
}

.nav-menu a:hover, .nav-menu a:focus {
  background-color: var(--background-secondary);
  text-decoration: none;
}

.nav-menu a.active {
  color: var(--primary-blue);
  background-color: var(--background-secondary);
}

/* ========================================
   Breadcrumbs
======================================== */
.breadcrumb {
  padding: var(--spacing-sm) 0;
}

.breadcrumb ol {
  display: flex;
  list-style: none;
  gap: var(--spacing-xs);
  font-size: var(--font-size-sm);
}

.breadcrumb li:not(:last-child)::after {
  content: ">";
  margin-left: var(--spacing-xs);
  color: var(--text-secondary);
}

.breadcrumb a {
  color: var(--text-secondary);
}

/* ========================================
   Cards & Content Blocks
======================================== */
.card {
  background-color: var(--background-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
  transition: all 0.2s ease;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
}

.card-highlight {
  background-color: var(--background-secondary);
  border: 2px solid var(--primary-blue);
  padding: var(--spacing-md);
}

.price-card {
  background: linear-gradient(135deg, var(--background-secondary), var(--background-primary));
  border-left: 4px solid var(--success-green);
  padding: var(--spacing-md);
}

.warning-card {
  background-color: #FFF8F0;
  border-left: 4px solid var(--warning-orange);
  padding: var(--spacing-lg);
  margin-top: var(--spacing-md);
}

/* ========================================
   Quick Navigation (CTA Buttons)
======================================== */
.quick-nav {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-sm);
  margin: var(--spacing-md) 0;
}

.quick-nav-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-lg);
  background-color: var(--background-secondary);
  border-radius: var(--radius-lg);
  color: var(--text-primary);
  text-decoration: none;
  transition: all 0.2s ease;
}

.quick-nav-item:hover, .quick-nav-item:focus {
  background-color: var(--hover-background);
  transform: translateX(4px);
  text-decoration: none;
}

.quick-nav-item::after {
  content: "→";
  font-weight: bold;
  color: var(--primary-blue);
}

/* ========================================
   Table of Contents
======================================== */
.toc {
  background-color: var(--background-secondary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin: var(--spacing-md) 0;
}

.toc h3 {
  font-size: var(--font-size-lg);
  margin-bottom: var(--spacing-sm);
  margin-top: 0;
}

.toc ul {
  list-style: none;
}

.toc li {
  margin-bottom: var(--spacing-xs);
}

.toc a {
  color: var(--text-primary);
  display: block;
  padding: var(--spacing-xs);
  border-radius: var(--radius-sm);
  transition: all 0.2s ease;
}

.toc a:hover, .toc a:focus {
  background-color: var(--background-primary);
  text-decoration: none;
}

/* ========================================
   FAQ Section (Details/Summary)
======================================== */
.faq {
  margin: var(--spacing-md) 0;
}

details {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-sm);
  overflow: hidden;
}

details[open] {
  border-color: var(--primary-blue);
}

summary {
  padding: var(--spacing-lg);
  background-color: var(--background-secondary);
  cursor: pointer;
  font-weight: 500;
  transition: all 0.2s ease;
  user-select: none;
}

summary:hover, summary:focus {
  background-color: var(--hover-background);
  outline: none;
}

details[open] summary {
  background-color: var(--primary-blue);
  color: white;
}

.faq-content {
  padding: var(--spacing-lg);
  background-color: var(--background-primary);
}

/* ========================================
   Footer
======================================== */
footer {
  background-color: var(--background-secondary);
  border-top: 1px solid var(--border-color);
  margin-top: var(--spacing-lg);
  padding: var(--spacing-md) 0 var(--spacing-sm);
}

.footer-content {
  text-align: center;
}

.footer-nav {
  display: flex;
  justify-content: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-md);
  flex-wrap: wrap;
}

.footer-nav a {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

.footer-info {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  line-height: 1.5;
}

.disclaimer {
  background-color: var(--background-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: var(--spacing-lg);
  margin: var(--spacing-md) 0;
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

/* ========================================
   Utilities
======================================== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.my-lg { margin: var(--spacing-lg) 0; }

.text-success { color: var(--success-green); }
.text-warning { color: var(--warning-orange); }
.text-primary { color: var(--primary-blue); }
.text-muted { color: var(--text-secondary); }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ========================================
   Responsive Design - Tablet (768px+)
======================================== */
@media (min-width: 768px) {
  :root {
    --font-size-3xl: 40px;
    --font-size-4xl: 48px;
  }
  
  .container {
    padding: 0 var(--spacing-md);
  }
  
  .grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
  }
  
  .quick-nav {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .nav-menu {
    gap: var(--spacing-lg);
  }
  
  .section {
    padding: var(--spacing-md) 0;
  }
  
  /* Two-column layout for content pages */
  .content-layout {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: var(--spacing-lg);
    align-items: start;
  }
  
  .toc {
    position: sticky;
    top: 120px;
  }
}

/* ========================================
   Responsive Design - Desktop (1024px+)
======================================== */
@media (min-width: 1024px) {
  .container {
    padding: 0 var(--spacing-lg);
  }
  
  .grid {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-xl);
  }
  
  .quick-nav {
    grid-template-columns: repeat(3, 1fr);
  }
  
  h1 {
    font-size: var(--font-size-4xl);
  }
  
  .content-layout {
    grid-template-columns: 1fr 350px;
  }
  
  /* Enhanced hover effects on desktop */
  .card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
  }
}

/* ========================================
   Print Styles
======================================== */
@media print {
  header, footer, .toc, .quick-nav {
    display: none;
  }
  
  body {
    font-size: 12pt;
    line-height: 1.4;
    color: black;
  }
  
  a::after {
    content: " (" attr(href) ")";
    font-size: 10pt;
    color: #666;
  }
  
  .card {
    border: 1px solid #ddd;
    page-break-inside: avoid;
  }
}

/* ========================================
   Focus & Accessibility
======================================== */
:focus-visible {
  outline: 2px solid var(--primary-blue);
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--text-primary);
  color: white;
  padding: 8px;
  text-decoration: none;
  border-radius: 4px;
  transition: top 0.2s;
}

.skip-link:focus {
  top: 6px;
}

/* Reduced motion for users who prefer it */
@media (prefers-reduced-motion: reduce) {
  *, ::before, ::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}