/* ===== Design Tokens ===== */
:root {
  /* 和紙×墨×琥珀 Color Palette */
  --washi-white: #FDFBF7;
  --sumi-black: #4A3B32;
  --kohaku-gold: #D4A574;
  --kohaku-deep: #B8860B;
  
  /* Neutral */
  --gray-100: #F5F5F5;
  --gray-200: #E8E5E0;
  --gray-400: #9E9A94;
  --gray-600: #6E6A64;
  
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 2rem;
  --space-xl: 4rem;
  
  /* Typography */
  --font-sans: 'Noto Sans JP', -apple-system, sans-serif;
  --font-serif: 'Noto Serif JP', Georgia, serif;
  
  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  font-weight: 300;
  background: var(--washi-white);
  color: var(--sumi-black);
  min-height: 100vh;
  line-height: 1.6;
}

a {
  color: inherit;
  text-decoration: none;
}

/* ===== Layout ===== */
.container {
  max-width: 480px;
  margin: 0 auto;
  padding: var(--space-lg) var(--space-md);
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
  min-height: 100vh;
}

/* ===== Hero ===== */
.hero {
  text-align: center;
  padding-top: var(--space-xl);
}

.logo {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-sm);
}

.sake-icon {
  width: 48px;
  height: 48px;
  color: var(--kohaku-gold);
}

.logo h1 {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  font-weight: 500;
  letter-spacing: 0.05em;
}

.tagline {
  margin-top: var(--space-md);
  font-size: 0.875rem;
  color: var(--gray-600);
  letter-spacing: 0.1em;
}

/* ===== Preview ===== */
.preview {
  display: flex;
  justify-content: center;
}

.phone-frame {
  width: 200px;
  height: 400px;
  background: var(--sumi-black);
  border-radius: 32px;
  padding: 12px;
  box-shadow: 
    0 25px 50px -12px rgba(74, 59, 50, 0.25),
    inset 0 0 0 2px rgba(255, 255, 255, 0.1);
}

.screen-placeholder {
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, var(--gray-100) 0%, var(--washi-white) 100%);
  border-radius: 24px;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

.grid-preview {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  padding: 16px;
  width: 100%;
}

.grid-item {
  aspect-ratio: 1;
  background: linear-gradient(145deg, var(--kohaku-gold), var(--kohaku-deep));
  border-radius: 8px;
  opacity: 0.6;
}

.grid-item:nth-child(2) { opacity: 0.4; }
.grid-item:nth-child(3) { opacity: 0.8; }
.grid-item:nth-child(4) { opacity: 0.5; }
.grid-item:nth-child(5) { opacity: 0.7; }
.grid-item:nth-child(6) { opacity: 0.3; }

/* ===== Download ===== */
.download {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
}

.version-cards {
  display: flex;
  gap: var(--space-md);
  width: 100%;
}

.version-card {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-lg) var(--space-md);
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: 16px;
  transition: all 0.3s var(--ease-out);
  cursor: pointer;
}

.version-card:hover {
  border-color: var(--kohaku-gold);
  transform: translateY(-2px);
  box-shadow: 0 12px 24px -8px rgba(74, 59, 50, 0.15);
}

.version-card.pro {
  border-color: var(--kohaku-gold);
  background: linear-gradient(180deg, white 0%, rgba(212, 165, 116, 0.05) 100%);
}

.card-header {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.version-name {
  font-weight: 500;
  font-size: 1.125rem;
}

.version-badge {
  font-size: 0.625rem;
  padding: 0.125rem 0.5rem;
  border-radius: 100px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.version-badge.free {
  background: var(--gray-200);
  color: var(--gray-600);
}

.version-badge.pro-badge {
  background: var(--kohaku-gold);
  color: white;
}

.card-icon {
  width: 32px;
  height: 32px;
  color: var(--sumi-black);
  opacity: 0.6;
}

.file-size {
  font-size: 0.75rem;
  color: var(--gray-400);
}

.platform-note {
  font-size: 0.75rem;
  color: var(--gray-400);
}

/* ===== Features ===== */
.features {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
}

.feature {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-xs);
}

.feature svg {
  width: 24px;
  height: 24px;
  color: var(--sumi-black);
  opacity: 0.5;
}

.feature span {
  font-size: 0.625rem;
  color: var(--gray-400);
  letter-spacing: 0.1em;
}

/* ===== Footer ===== */
footer {
  margin-top: auto;
  text-align: center;
  padding: var(--space-lg) 0;
}

footer p {
  font-size: 0.75rem;
  color: var(--gray-400);
}

/* ===== Dark Mode ===== */
@media (prefers-color-scheme: dark) {
  :root {
    --washi-white: #121212;
    --sumi-black: #E8E5E0;
    --gray-100: #1E1E1E;
    --gray-200: #2A2A2A;
    --gray-400: #6E6A64;
    --gray-600: #9E9A94;
  }
  
  .phone-frame {
    background: #2A2A2A;
  }
  
  .screen-placeholder {
    background: linear-gradient(135deg, #1E1E1E 0%, #2A2A2A 100%);
  }
  
  .version-card {
    background: #1E1E1E;
    border-color: #2A2A2A;
  }
  
  .version-card:hover {
    border-color: var(--kohaku-gold);
    box-shadow: 0 12px 24px -8px rgba(0, 0, 0, 0.5);
  }
  
  .version-card.pro {
    background: linear-gradient(180deg, #1E1E1E 0%, rgba(212, 165, 116, 0.08) 100%);
  }
  
  .version-badge.free {
    background: #2A2A2A;
    color: #9E9A94;
  }
}

/* ===== Responsive ===== */
@media (min-width: 768px) {
  .container {
    padding: var(--space-xl);
  }
  
  .phone-frame {
    width: 240px;
    height: 480px;
  }
}