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

/* ── Base ── */
html {
  font-size: 100%;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--font-normal);
  line-height: var(--leading-normal);
  color: var(--color-text-primary);
  background: var(--color-surface-0);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ── Focus ── */
:focus-visible {
  outline: 2px solid var(--color-focus-400);
  outline-offset: 2px;
}

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

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

/* ── Container ── */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.container:first-child {
  padding-top: var(--space-xl);
  padding-bottom: var(--space-xl);
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-md);
  }
  
  .container:first-child {
    padding-top: var(--space-lg);
    padding-bottom: var(--space-lg);
  }
}

/* ──────────────────────────────────────────────
   Header
   ────────────────────────────────────────────── */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-surface-1);
  border-bottom: 1px solid var(--color-border-100);
  backdrop-filter: saturate(180%) blur(8px);
  /* Dark mode header bg */
  background: color-mix(in srgb, var(--color-surface-1) 90%, transparent);
}

@media (prefers-color-scheme: dark) {
  .site-header {
    background: color-mix(in srgb, var(--color-surface-1) 90%, transparent);
  }
}

.site-header__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
}

/* ── Brand ── */
.site-header__brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  flex-shrink: 0;
}

.site-header__logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-md);
  background: var(--color-brand-500);
  color: var(--color-text-inverse);
  font-size: var(--text-xs);
  font-weight: var(--font-bold);
  letter-spacing: var(--tracking-widest);
}

.site-header__label {
  font-size: var(--text-base);
  font-weight: var(--font-semibold);
  color: var(--color-text-primary);
}

/* ── Navigation ── */
.site-header__nav {
  display: flex;
  align-items: center;
  gap: 0;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--color-text-secondary);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  transition: color var(--duration-fast) var(--ease-out),
              background-color var(--duration-fast) var(--ease-out);
}

.nav-link:hover {
  color: var(--color-text-primary);
  background: var(--color-surface-2);
}

.nav-link--active {
  color: var(--color-brand-600);
  font-weight: var(--font-semibold);
}

@media (prefers-color-scheme: dark) {
  .nav-link--active {
    color: var(--color-brand-300);
  }
}

.nav-link__chevron {
  width: 12px;
  height: 12px;
  transition: transform var(--duration-fast) var(--ease-out);
}

.nav-link--dropdown[aria-expanded="true"] .nav-link__chevron {
  transform: rotate(180deg);
}

/* ── Dropdown ── */
.dropdown {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  margin-top: var(--space-xs);
  background: var(--color-surface-0);
  border: 1px solid var(--color-border-200);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  min-width: 180px;
  padding: var(--space-xs) 0;
  display: none;
}

.dropdown:is([open], :has(.dropdown__item--active)) {
  display: block;
}

.dropdown__item {
  display: block;
  width: 100%;
  padding: var(--space-xs) var(--space-md);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  transition: background-color var(--duration-fast) var(--ease-out);
}

.dropdown__item:hover,
.dropdown__item--active {
  background: var(--color-surface-2);
  color: var(--color-text-primary);
}

.dropdown__item--active {
  background: var(--color-brand-50);
  font-weight: var(--font-medium);
}

@media (prefers-color-scheme: dark) {
  .dropdown__item--active {
    background: color-mix(in srgb, var(--color-brand-500) 15%, transparent);
  }
}

/* ── Theme Toggle ── */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  transition: background-color var(--duration-fast) var(--ease-out),
              color var(--duration-fast) var(--ease-out);
}

.theme-toggle:hover {
  background: var(--color-surface-2);
  color: var(--color-text-primary);
}

.theme-toggle__icon {
  display: none;
}

.theme-toggle__icon--sun {
  display: block;
}

.theme-toggle__icon--moon {
  display: none;
}

[data-theme="dark"] .theme-toggle__icon--sun {
  display: none;
}

[data-theme="dark"] .theme-toggle__icon--moon {
  display: block;
}

/* ── Mobile Nav Toggle ── */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: var(--space-xxs);
  width: 40px;
  height: 40px;
  padding: var(--space-xs);
  border-radius: var(--radius-md);
}

@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }
}

.nav-toggle__bar {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-text-secondary);
  border-radius: 1px; /* micro-detail: bar width too thin for token */
  transition: transform var(--duration-base) var(--ease-out),
              opacity var(--duration-base) var(--ease-out);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Mobile Nav ── */

@media (max-width: 768px) {
  .site-header__nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-surface-1);
    border-bottom: 1px solid var(--color-border-100);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: var(--space-md) 0;
    display: none;
  }

  .site-header__nav.nav--open,
  [aria-expanded="true"] + .site-header__nav {
    display: flex;
  }

  .nav-link {
    padding: var(--space-sm) var(--space-lg);
    width: 100%;
  }
}

/* ──────────────────────────────────────────────
    Main
    ────────────────────────────────────────────── */

.site-main {
  flex: 1;
  padding: var(--space-xxl) 0;
}

/* ──────────────────────────────────────────────
    Footer
    ────────────────────────────────────────────── */

.site-footer {
  background: var(--color-surface-1);
  border-top: 1px solid var(--color-border-100);
  padding: var(--space-xl) 0 var(--space-lg);
  margin-top: auto;
}

.site-footer__inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-xl);
  margin-bottom: var(--space-lg);
}

@media (max-width: 640px) {
  .site-footer__inner {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  .site-footer {
    padding: var(--space-xl) 0 var(--space-md);
  }
}

.site-footer__heading {
  font-size: var(--text-xs);
  font-weight: var(--font-semibold);
  letter-spacing: var(--tracking-widest);
  text-transform: uppercase;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-sm);
}

.site-footer__col .site-header__logo {
  margin-bottom: var(--space-sm);
}

.site-footer__small {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

.site-footer__link {
  display: block;
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  padding: var(--space-xs) 0;
  transition: color var(--duration-fast) var(--ease-out);
}

.site-footer__link:hover {
  color: var(--color-text-primary);
}

.site-footer__link[aria-disabled="true"] {
    color: var(--color-text-tertiary);
    cursor: default;
  }

.site-footer__link--active {
    color: var(--color-text-primary);
    font-weight: var(--font-semibold);
  }

.site-footer__bottom {
    border-top: 1px solid var(--color-border-100);
    padding-top: var(--space-lg);
  }

.site-footer__copy {
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
}

/* ── Unified footer variant for 3D pages with fixed positioning ── */

.site-footer--fixed {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: var(--space-xs) 0;
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  background: color-mix(in srgb, var(--color-surface-0) 85%, transparent);
  border-top: 1px solid var(--color-border-100);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  text-align: center;
}

.site-footer--fixed a {
  color: var(--color-brand-500);
  text-decoration: none;
  font-size: inherit;
}

.site-footer--fixed a:hover {
  text-decoration: underline;
}

.site-footer--fixed__hint {
  opacity: 0.5;
  user-select: none;
}