/* ============================================
   Design Tokens & Foundation
   ============================================ */

:root {
  /* Colors */
  --color-white: #FFFFFF;
  --color-bg: #FAFAFA;
  --color-surface: #F3F4F6;
  --color-text: #1A1A2E;
  --color-text-secondary: #6B7280;
  --color-text-light: #9CA3AF;
  --color-primary: #2563EB;
  --color-primary-hover: #1D4ED8;
  --color-primary-light: #EFF6FF;
  --color-border: #E5E7EB;
  --color-border-light: #F3F4F6;
  --color-success: #059669;
  --color-error: #DC2626;

  /* Typography */
  --font-sans: 'Noto Sans JP', 'Inter', system-ui, -apple-system, sans-serif;
  --font-en: 'Inter', system-ui, -apple-system, sans-serif;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;

  --leading-tight: 1.25;
  --leading-normal: 1.75;
  --leading-relaxed: 1.875;

  --weight-normal: 400;
  --weight-medium: 500;
  --weight-bold: 700;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Layout */
  --max-width: 1200px;
  --max-width-narrow: 800px;
  --header-height: 72px;

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;
}

/* ============================================
   CSS Reset
   ============================================ */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--color-text);
  background-color: var(--color-white);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

img, video {
  max-width: 100%;
  height: auto;
  display: block;
}

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

a:hover {
  color: var(--color-primary-hover);
}

ul, ol {
  list-style: none;
}

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

h1, h2, h3, h4, h5, h6 {
  line-height: var(--leading-tight);
  font-weight: var(--weight-bold);
}

/* ============================================
   Typography
   ============================================ */

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }
h6 { font-size: var(--text-base); }

p {
  margin-bottom: var(--space-4);
}

p:last-child {
  margin-bottom: 0;
}

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

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

.text-light {
  color: var(--color-text-light);
}

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

/* ============================================
   Layout Utilities
   ============================================ */

.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-6);
  padding-right: var(--space-6);
}

.container-narrow {
  width: 100%;
  max-width: var(--max-width-narrow);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-6);
  padding-right: var(--space-6);
}

.section {
  padding-top: var(--space-20);
  padding-bottom: var(--space-20);
}

.section-sm {
  padding-top: var(--space-12);
  padding-bottom: var(--space-12);
}

.section-bg {
  background-color: var(--color-bg);
}

/* Grid */
.grid {
  display: grid;
  gap: var(--space-8);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr);
}

/* Flex */
.flex {
  display: flex;
}

.flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}

.flex-between {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.flex-col {
  flex-direction: column;
}

.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

/* ============================================
   Responsive
   ============================================ */

@media (max-width: 1024px) {
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --text-4xl: 1.875rem;
    --text-5xl: 2.25rem;
  }

  .section {
    padding-top: var(--space-12);
    padding-bottom: var(--space-12);
  }

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .container {
    padding-left: var(--space-4);
    padding-right: var(--space-4);
  }

  .hide-mobile {
    display: none !important;
  }
}

@media (min-width: 769px) {
  .hide-desktop {
    display: none !important;
  }
}

/* ============================================
   Accessibility
   ============================================ */

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

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}