/* ==================== Variables ==================== */
:root {
  --color-bg: #fafafa;
  --color-surface: #ffffff;
  --color-text: #1a1a1a;
  --color-text-secondary: #666666;
  --color-accent: #5b7ce6;
  --color-accent-hover: #4a6bd5;
  --color-border: rgba(0, 0, 0, 0.08);
  --color-shadow: rgba(0, 0, 0, 0.06);
  --color-glass: rgba(255, 255, 255, 0.7);

  --gradient-1: #e0e7ff;
  --gradient-2: #fce7f3;
  --gradient-3: #dbeafe;

  --font-sans: system-ui, -apple-system, "Segoe UI", "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic", sans-serif;

  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --color-bg: #0f0f0f;
  --color-surface: #1a1a1a;
  --color-text: #f5f5f5;
  --color-text-secondary: #a3a3a3;
  --color-accent: #6b8aff;
  --color-accent-hover: #5a79ee;
  --color-border: rgba(255, 255, 255, 0.1);
  --color-shadow: rgba(0, 0, 0, 0.3);
  --color-glass: rgba(26, 26, 26, 0.7);

  --gradient-1: #1e293b;
  --gradient-2: #312e81;
  --gradient-3: #1e3a8a;
}

/* Font Size Variables */
[data-font-size="small"] {
  --font-size-base: 14px;
  --font-size-lg: 16px;
  --font-size-xl: 20px;
  --font-size-2xl: 24px;
  --font-size-3xl: 32px;
}

[data-font-size="medium"] {
  --font-size-base: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 22px;
  --font-size-2xl: 28px;
  --font-size-3xl: 36px;
}

[data-font-size="large"] {
  --font-size-base: 18px;
  --font-size-lg: 20px;
  --font-size-xl: 24px;
  --font-size-2xl: 32px;
  --font-size-3xl: 40px;
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overscroll-behavior: none;
}

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base, 16px);
  line-height: 1.75;
  color: var(--color-text);
  background: var(--color-bg);
  transition: background var(--transition-base), color var(--transition-base);
  min-height: 100vh;
  overflow-x: hidden;
  overscroll-behavior: none;
}

/* ==================== Background Gradient Animation ==================== */
.bg-gradient {
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: linear-gradient(
  45deg,
  var(--gradient-1) 0%,
  var(--gradient-2) 50%,
  var(--gradient-3) 100%
  );
  opacity: 0.15;
  z-index: -1;
  animation: gradientShift 20s ease infinite;
}

@keyframes gradientShift {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  33% { transform: translate(-5%, -5%) rotate(3deg); }
  66% { transform: translate(5%, 5%) rotate(-3deg); }
}

@media (prefers-reduced-motion: reduce) {
  .bg-gradient {
    animation: none;
  }
}

/* ==================== Controls ==================== */
.controls-wrapper {
  position: fixed;
  top: var(--spacing-md);
  right: var(--spacing-md);
  z-index: 1000;
}

.controls {
  display: flex;
  gap: var(--spacing-xs);
  background: var(--color-glass);
  backdrop-filter: blur(12px);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: var(--spacing-xs);
  box-shadow: 0 4px 12px var(--color-shadow);
}

.control-btn {
  width: 40px;
  height: 40px;
  border: none;
  background: transparent;
  color: var(--color-text);
  border-radius: var(--radius-full);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  position: relative;
}

.control-btn:hover {
  background: var(--color-accent);
  color: white;
  transform: scale(1.05);
}

.control-btn:active {
  transform: scale(0.95);
}

.control-btn:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

[data-theme="light"] .icon-sun {
  display: block;
}

[data-theme="light"] .icon-moon {
  display: none;
}

[data-theme="dark"] .icon-sun {
  display: none;
}
[data-theme="dark"] .icon-moon {
  display: block;
}
.font-size-controls {
  display: flex;
  gap: 4px;
}
.font-btn {
  font-size: 12px;
  font-weight: 600;
}
.font-btn[data-size="medium"] {
  font-size: 14px;
}
.font-btn[data-size="large"] {
  font-size: 16px;
}
.font-btn.active {
  background: var(--color-accent);
  color: white;
}
/* ==================== Container ==================== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}
/* ==================== Header ==================== */
.header {
  text-align: center;
  padding: var(--spacing-2xl) var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}
.header-title {
  font-size: var(--font-size-3xl, 36px);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--spacing-sm);
  background: linear-gradient(135deg, var(--color-accent) 0%, #9333ea 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: fadeInUp 0.6s ease-out;
}
.header-subtitle {
  font-size: var(--font-size-lg, 18px);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
  animation: fadeInUp 0.6s ease-out 0.1s backwards;
}
.last-updated {
  display: inline-block;
  font-size: var(--font-size-base, 16px);
  color: var(--color-text-secondary);
  padding: var(--spacing-xs) var(--spacing-md);
  background: var(--color-glass);
  backdrop-filter: blur(8px);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  animation: fadeInUp 0.6s ease-out 0.2s backwards;
}
.lang-switcher {
  margin-top: var(--spacing-md);
  display: inline-flex;
  gap: 4px;
  padding: 4px;
  background: var(--color-glass);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  backdrop-filter: blur(8px);
  animation: fadeInUp 0.6s ease-out 0.25s backwards;
}
.lang-option {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 6px 14px;
  border-radius: var(--radius-full);
  font-size: var(--font-size-base, 14px);
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: all var(--transition-fast);
}
.lang-option:hover {
  color: var(--color-accent);
  background: rgba(91, 124, 230, 0.1);
}
.lang-option.is-active {
  color: var(--color-accent);
  background: rgba(91, 124, 230, 0.12);
  font-weight: 600;
}
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
/* ==================== Purpose Card ==================== */
.purpose-card {
  margin-bottom: var(--spacing-xl);
  animation: fadeInUp 0.6s ease-out 0.3s backwards;
}
.purpose-title {
  font-size: var(--font-size-xl, 22px);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--color-accent);
}
.purpose-text {
  font-size: var(--font-size-lg, 18px);
  line-height: 1.8;
}
/* ==================== Glass Card ==================== */
.glass-card {
  background: var(--color-glass);
  backdrop-filter: blur(12px);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  box-shadow: 0 4px 16px var(--color-shadow);
  transition: all var(--transition-base);
}
.glass-card:hover {
  box-shadow: 0 8px 24px var(--color-shadow);
  transform: translateY(-2px);
}
@media (prefers-reduced-motion: reduce) {
  .glass-card:hover {
    transform: none;
  }
}
/* ==================== Layout ==================== */
.layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: var(--spacing-xl);
  margin-bottom: var(--spacing-2xl);
}
@media (max-width: 1024px) {
  .layout {
    grid-template-columns: 1fr;
  }
}
/* ==================== Table of Contents ==================== */
.toc {
  animation: fadeInUp 0.6s ease-out 0.4s backwards;
}
.toc-sticky {
  position: sticky;
  top: var(--spacing-md);
  max-height: calc(100vh - var(--spacing-2xl));
  overflow-y: auto;
  padding-right: var(--spacing-xs);
  scrollbar-width: none;
  -ms-overflow-style: none;
}
.toc-sticky::-webkit-scrollbar {
  width: 0;
  height: 0;
}
.toc-title {
  font-size: var(--font-size-lg, 18px);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}
.toc-list {
  list-style: none;
}
.toc-link {
  display: block;
  padding: var(--spacing-xs) var(--spacing-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
  border-radius: var(--radius-sm);
  font-size: var(--font-size-base, 16px);
  transition: all var(--transition-fast);
  position: relative;
  margin-bottom: 4px;
}
.toc-link::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 3px;
  height: 0;
  background: var(--color-accent);
  border-radius: 2px;
  transition: height var(--transition-fast);
}
.toc-link:hover {
  color: var(--color-accent);
  background: rgba(91, 124, 230, 0.1);
}
.toc-link.active {
  color: var(--color-accent);
  font-weight: 600;
  background: rgba(91, 124, 230, 0.1);
}
.toc-link.active::before {
  height: 100%;
}
@media (max-width: 1024px) {
  .toc {
    margin-bottom: var(--spacing-lg);
  }
  .toc-sticky {
    position: static;
  }

  .toc-list {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
  }

  .toc-link {
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--color-glass);
    border: 1px solid var(--color-border);
  }
}
/* ==================== Content Sections ==================== */
.content {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}
.section {
  animation: fadeInUp 0.6s ease-out backwards;
  scroll-margin-top: var(--spacing-xl);
}
.section:nth-child(1) { animation-delay: 0.5s; }
.section:nth-child(2) { animation-delay: 0.55s; }
.section:nth-child(3) { animation-delay: 0.6s; }
.section:nth-child(4) { animation-delay: 0.65s; }
.section:nth-child(5) { animation-delay: 0.7s; }
.section:nth-child(6) { animation-delay: 0.75s; }
.section:nth-child(7) { animation-delay: 0.8s; }
.section:nth-child(8) { animation-delay: 0.85s; }
.section:nth-child(9) { animation-delay: 0.9s; }
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-md);
}
.section-title {
  font-size: var(--font-size-xl, 22px);
  font-weight: 600;
  color: var(--color-text);
}
.accordion-toggle {
  width: 36px;
  height: 36px;
  border: none;
  background: transparent;
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}
.accordion-toggle:hover {
  background: rgba(91, 124, 230, 0.1);
  color: var(--color-accent);
}
.accordion-toggle svg {
  transition: transform var(--transition-base);
}
.section.collapsed .accordion-toggle svg {
  transform: rotate(-90deg);
}
.section-content {
  max-height: 5000px;
  overflow: hidden;
  transition: max-height var(--transition-slow), opacity var(--transition-base);
}
.section.collapsed .section-content {
  max-height: 0;
  opacity: 0;
}
.section-content p {
  margin-bottom: var(--spacing-md);
  max-width: 75ch;
}
.section-content p:last-of-type {
  margin-bottom: var(--spacing-lg);
}
.info-list {
  list-style: none;
  margin: var(--spacing-md) 0;
  padding-left: var(--spacing-md);
}
.info-list li {
  position: relative;
  padding-left: var(--spacing-md);
  margin-bottom: var(--spacing-sm);
}
.info-list li::before {
  content: '•';
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: bold;
}
.info-list--numbered {
  padding-left: 0;
}
.info-list--numbered li {
  padding-left: 0;
}
.info-list--numbered li::before {
  content: none;
}
.note {
  padding: var(--spacing-sm) var(--spacing-md);
  background: rgba(91, 124, 230, 0.05);
  border-left: 3px solid var(--color-accent);
  border-radius: var(--radius-sm);
  font-size: 0.95em;
  color: var(--color-text-secondary);
}
/* ==================== Copy Button ==================== */
.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-xs) var(--spacing-md);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  font-size: 0.875em;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}
.copy-btn:hover {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: white;
  transform: translateY(-1px);
}
.copy-btn:active {
  transform: translateY(0);
}
.copy-btn svg {
  width: 16px;
  height: 16px;
}
/* ==================== Footer ==================== */
.footer {
  text-align: center;
  padding: var(--spacing-xl) var(--spacing-md);
  background: var(--color-glass);
  backdrop-filter: blur(12px);
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-2xl);
}
.footer-contact {
  font-size: var(--font-size-base, 16px);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-sm);
}
.footer-copyright {
  font-size: 0.875em;
  color: var(--color-text-secondary);
}
/* ==================== Back to Top Button ==================== */
.back-to-top {
  position: fixed;
  bottom: var(--spacing-lg);
  right: var(--spacing-lg);
  width: 48px;
  height: 48px;
  border: none;
  background: var(--color-accent);
  color: white;
  border-radius: var(--radius-full);
  box-shadow: 0 4px 16px rgba(91, 124, 230, 0.3);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all var(--transition-base);
  z-index: 999;
}
.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(91, 124, 230, 0.4);
}
.back-to-top:active {
  transform: translateY(-2px);
}
/* ==================== Toast ==================== */
.toast-container {
  position: fixed;
  top: var(--spacing-lg);
  left: 50%;
  transform: translateX(-50%);
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  pointer-events: none;
}
.toast {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--spacing-md) var(--spacing-lg);
  box-shadow: 0 8px 32px var(--color-shadow);
  backdrop-filter: blur(12px);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  animation: toastSlideIn 0.3s ease-out;
  pointer-events: auto;
}
.toast.success {
  border-left: 4px solid #10b981;
}
.toast-icon {
  width: 24px;
  height: 24px;
  color: #10b981;
}
.toast-message {
  font-size: var(--font-size-base, 16px);
  color: var(--color-text);
}
@keyframes toastSlideIn {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
@keyframes toastSlideOut {
  from {
    opacity: 1;
    transform: translateY(0);
  }
  to {
    opacity: 0;
    transform: translateY(-20px);
  }
}
/* ==================== Responsive ==================== */
@media (max-width: 768px) {
  :root {
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
  }
  .controls-wrapper {
    top: var(--spacing-sm);
    right: var(--spacing-sm);
  }

  .header {
    padding: var(--spacing-xl) var(--spacing-md);
  }
  .lang-switcher {
    flex-wrap: wrap;
    justify-content: center;
  }
  .lang-option {
    padding: 6px 10px;
    font-size: 0.9em;
  }

  .back-to-top {
    bottom: var(--spacing-md);
    right: var(--spacing-md);
    width: 44px;
    height: 44px;
  }
}
/* ==================== Print Styles ==================== */
@media print {
  .controls-wrapper,
  .toc,
  .back-to-top,
  .copy-btn,
  .accordion-toggle {
    display: none;
  }
  .section-content {
    max-height: none !important;
    opacity: 1 !important;
  }

  .glass-card {
    box-shadow: none;
    border: 1px solid #ddd;
  }
}
/* ==================== Accessibility ==================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}