/* ============================================
   JAXA Earth API → VRChat Terrain Generator
   GitHub Pages - Apple-inspired Design
   ============================================ */

/* ===== CSS Variables (Apple Design System) ===== */
:root {
  /* Colors */
  --color-primary: #007AFF;
  --color-primary-dark: #0051D5;
  --color-secondary: #5856D6;
  --color-success: #34C759;
  --color-warning: #FF9500;
  --color-error: #FF3B30;
  
  /* Grayscale */
  --color-text-primary: #1D1D1F;
  --color-text-secondary: #86868B;
  --color-text-tertiary: #C7C7CC;
  --color-bg-primary: #FFFFFF;
  --color-bg-secondary: #F5F5F7;
  --color-bg-tertiary: #FAFAFA;
  --color-border: #D2D2D7;
  
  /* Spacing (8px base unit) */
  --spacing-xs: 0.5rem;   /* 8px */
  --spacing-sm: 1rem;     /* 16px */
  --spacing-md: 1.5rem;   /* 24px */
  --spacing-lg: 2rem;     /* 32px */
  --spacing-xl: 3rem;     /* 48px */
  --spacing-2xl: 4rem;    /* 64px */
  --spacing-3xl: 6rem;    /* 96px */
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-family-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, "Courier New", monospace;
  
  /* Font Sizes */
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;    /* 20px */
  --font-size-2xl: 1.5rem;    /* 24px */
  --font-size-3xl: 1.875rem;  /* 30px */
  --font-size-4xl: 2.25rem;   /* 36px */
  --font-size-5xl: 3rem;      /* 48px */
  --font-size-6xl: 3.75rem;   /* 60px */
  
  /* Line Heights */
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* Border Radius */
  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  --radius-full: 9999px;
  
  /* Shadows (Apple-style) */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1);
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  overflow-x: hidden;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: var(--line-height-tight);
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
}

h1 {
  font-size: var(--font-size-6xl);
  font-weight: 700;
  margin-bottom: var(--spacing-lg);
}

h2 {
  font-size: var(--font-size-4xl);
  margin-bottom: var(--spacing-md);
  margin-top: var(--spacing-2xl);
}

h3 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-sm);
  margin-top: var(--spacing-xl);
}

h4 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-sm);
}

p {
  margin-bottom: var(--spacing-md);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

code {
  font-family: var(--font-family-mono);
  font-size: 0.9em;
  background-color: var(--color-bg-secondary);
  padding: 0.2em 0.4em;
  border-radius: var(--radius-sm);
  color: var(--color-text-primary);
}

pre {
  font-family: var(--font-family-mono);
  font-size: var(--font-size-sm);
  background-color: var(--color-bg-secondary);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin-bottom: var(--spacing-md);
  border: 1px solid var(--color-border);
}

pre code {
  background: none;
  padding: 0;
}

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

.section {
  padding: var(--spacing-3xl) 0;
}

/* ===== Header ===== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--color-border);
  padding: var(--spacing-md) 0;
  transition: all var(--transition-base);
}

.header.scrolled {
  box-shadow: var(--shadow-sm);
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.logo {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.logo-icon {
  font-size: var(--font-size-2xl);
}

.nav {
  display: flex;
  gap: var(--spacing-lg);
  align-items: center;
}

.lang-toggle {
  display: flex;
  gap: var(--spacing-xs);
  background-color: var(--color-bg-secondary);
  padding: var(--spacing-xs);
  border-radius: var(--radius-full);
  border: none;
}

.lang-toggle button {
  padding: var(--spacing-xs) var(--spacing-sm);
  border: none;
  background: transparent;
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  font-weight: 500;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: var(--font-family);
}

.lang-toggle button.active {
  background-color: var(--color-bg-primary);
  color: var(--color-text-primary);
  box-shadow: var(--shadow-sm);
}

.lang-toggle button:hover {
  color: var(--color-text-primary);
}

/* ===== Hero Section ===== */
.hero {
  text-align: center;
  padding: var(--spacing-3xl) 0;
  background: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
}

.hero-title {
  font-size: var(--font-size-6xl);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.1;
}

.hero-subtitle {
  font-size: var(--font-size-2xl);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xl);
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.hero-cta {
  display: inline-flex;
  gap: var(--spacing-sm);
  align-items: center;
  padding: var(--spacing-md) var(--spacing-xl);
  background-color: var(--color-primary);
  color: white;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: var(--font-size-lg);
  transition: all var(--transition-base);
  box-shadow: var(--shadow-md);
  border: none;
  cursor: pointer;
  text-decoration: none;
}

.hero-cta:hover {
  background-color: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  text-decoration: none;
  color: white;
}

/* ===== Card Components ===== */
.card {
  background-color: var(--color-bg-primary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
  transition: all var(--transition-base);
  margin-bottom: var(--spacing-lg);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.card-title {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-primary);
}

.card-content {
  color: var(--color-text-secondary);
}

/* ===== Feature Grid ===== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-xl);
}

.feature-card {
  background-color: var(--color-bg-primary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
  transition: all var(--transition-base);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}

.feature-icon {
  font-size: var(--font-size-4xl);
  margin-bottom: var(--spacing-md);
  display: block;
}

.feature-title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-primary);
}

.feature-description {
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* ===== Code Blocks ===== */
.code-block {
  position: relative;
  margin: var(--spacing-lg) 0;
}

.code-block-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-sm) var(--spacing-md);
  background-color: var(--color-bg-secondary);
  border-top-left-radius: var(--radius-md);
  border-top-right-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  border-bottom: none;
}

.code-block-title {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-secondary);
  font-family: var(--font-family-mono);
}

.code-block-copy {
  background: none;
  border: none;
  color: var(--color-primary);
  font-size: var(--font-size-sm);
  cursor: pointer;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  font-family: var(--font-family);
}

.code-block-copy:hover {
  background-color: var(--color-bg-primary);
}

.code-block-content {
  margin-top: 0;
  border-top-left-radius: 0;
  border-top-right-radius: 0;
}

/* ===== Steps ===== */
.steps {
  counter-reset: step-counter;
  list-style: none;
  padding: 0;
}

.step {
  counter-increment: step-counter;
  display: flex;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-xl);
  padding: var(--spacing-lg);
  background-color: var(--color-bg-secondary);
  border-radius: var(--radius-lg);
  border-left: 4px solid var(--color-primary);
}

.step::before {
  content: counter(step-counter);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  background-color: var(--color-primary);
  color: white;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: var(--font-size-xl);
  flex-shrink: 0;
}

.step-content {
  flex: 1;
}

.step-title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-primary);
}

.step-description {
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* ===== Badges ===== */
.badge {
  display: inline-block;
  padding: var(--spacing-xs) var(--spacing-sm);
  background-color: var(--color-bg-secondary);
  color: var(--color-text-primary);
  border-radius: var(--radius-full);
  font-size: var(--font-size-sm);
  font-weight: 500;
  margin-right: var(--spacing-xs);
  margin-bottom: var(--spacing-xs);
}

.badge-primary {
  background-color: var(--color-primary);
  color: white;
}

.badge-success {
  background-color: var(--color-success);
  color: white;
}

/* ===== Footer ===== */
.footer {
  background-color: var(--color-bg-secondary);
  padding: var(--spacing-2xl) 0;
  margin-top: var(--spacing-3xl);
  border-top: 1px solid var(--color-border);
}

.footer-content {
  text-align: center;
  color: var(--color-text-secondary);
}

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

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
  :root {
    --font-size-6xl: 2.5rem;
    --font-size-5xl: 2rem;
    --font-size-4xl: 1.75rem;
    --spacing-3xl: 3rem;
    --spacing-2xl: 2rem;
  }
  
  .header-content {
    flex-direction: column;
    gap: var(--spacing-md);
  }
  
  .nav {
    width: 100%;
    justify-content: center;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
  
  .step {
    flex-direction: column;
    text-align: center;
  }
  
  .step::before {
    margin: 0 auto;
  }
  
  .container {
    padding: 0 var(--spacing-md);
  }
}

/* ===== Animations ===== */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeIn 0.6s ease-out;
}

/* ===== Utility Classes ===== */
.hidden {
  display: none !important;
}

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

.mt-lg {
  margin-top: var(--spacing-lg);
}

.mb-lg {
  margin-bottom: var(--spacing-lg);
}