/* ==========================================================================
   layout.css — Grid System, Header, Footer, Page Shell
   All values reference custom properties from base.css.
   ========================================================================== */

/* --------------------------------------------------------------------------
   Page Shell
   -------------------------------------------------------------------------- */

.page {
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
}

.page__main {
  flex: 1;
  width: 100%;
}

/* --------------------------------------------------------------------------
   Container
   -------------------------------------------------------------------------- */

.container {
  width: 100%;
  max-width: var(--content-width);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.container--narrow {
  max-width: var(--content-narrow);
}

/* --------------------------------------------------------------------------
   Grid System
   -------------------------------------------------------------------------- */

.grid {
  display: grid;
  gap: var(--space-6);
}

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

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

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

.grid--auto-fill {
  grid-template-columns: repeat(auto-fill, minmax(min(16rem, 100%), 1fr));
}

@media (max-width: 48em) {
  .grid--2,
  .grid--3,
  .grid--4 {
    grid-template-columns: 1fr;
  }
}

@media (min-width: 48em) and (max-width: 64em) {
  .grid--3,
  .grid--4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* --------------------------------------------------------------------------
   Header
   -------------------------------------------------------------------------- */

.header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  width: 100%;
  height: var(--header-height);
  background-color: var(--colour-chrome);
  border-bottom: 1px solid var(--colour-border);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--content-width);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.header__logo {
  font-family: var(--font-primary);
  font-size: var(--text-lg);
  font-weight: var(--weight-bold);
  color: var(--colour-text);
  white-space: nowrap;
}

.header__nav {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.header__nav-link {
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--colour-text-secondary);
  transition: color var(--transition-fast);
}

.header__nav-link:hover {
  color: var(--colour-accent);
}

.header__nav-link--active {
  color: var(--colour-accent);
}

/* Header dropdown navigation */
.header__dropdown {
  position: relative;
}

.header__dropdown-toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
}

.header__dropdown-chevron {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  cursor: pointer;
}

.header__dropdown-arrow {
  width: 1.3rem;
  height: 1.3rem;
  transition: transform var(--transition-fast);
}

.header__dropdown-chevron:hover .header__dropdown-arrow {
  transform: rotate(180deg);
}

.header__dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  z-index: var(--z-dropdown);
  min-width: 12rem;
  margin-top: var(--space-2);
  padding: var(--space-1) 0;
  background-color: var(--colour-surface);
  border: 1px solid var(--colour-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  visibility: hidden;
  transform: translateY(-0.25rem);
  transition: visibility var(--transition-fast), transform var(--transition-fast);
}

.header__dropdown:hover .header__dropdown-menu {
  visibility: visible;
  transform: translateY(0);
}

.header__dropdown-item {
  display: block;
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--colour-text);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.header__dropdown-item:hover {
  background-color: var(--colour-accent-subtle);
  color: var(--colour-accent);
}

.header__icons {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.header__icon-btn {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--space-10);
  height: var(--space-10);
  border-radius: var(--radius-md);
  color: var(--colour-text-secondary);
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.header__icon-btn:hover {
  color: var(--colour-accent);
  background-color: var(--colour-accent-subtle);
}

.header__icon-btn svg {
  width: var(--space-5);
  height: var(--space-5);
}

.header__badge {
  position: absolute;
  top: var(--space-1);
  right: var(--space-1);
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: var(--space-4);
  height: var(--space-4);
  padding-inline: var(--space-1);
  font-size: var(--text-xs);
  font-weight: var(--weight-bold);
  color: var(--colour-text-inverse);
  background-color: var(--colour-accent);
  border-radius: var(--radius-full);
  line-height: 1;
}

/* Header Search */
.header__search {
  position: relative;
  display: flex;
  align-items: center;
}

.header__search-form {
  overflow: hidden;
  width: 0;
  opacity: 0;
  transition: width var(--transition-base), opacity var(--transition-base);
}

.header__search.is-open .header__search-form {
  width: 14rem;
  opacity: 1;
}

.header__search-input {
  height: var(--space-10);
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-sm);
  border-radius: var(--radius-md);
}

@media (max-width: 48em) {
  .header__search.is-open .header__search-form {
    width: 10rem;
  }
}

/* Mobile menu toggle */
.header__menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: var(--space-10);
  height: var(--space-10);
  color: var(--colour-text);
}

@media (max-width: 48em) {
  .header__nav {
    display: none;
  }

  .header__nav.is-open {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    z-index: var(--z-overlay);
    background-color: var(--colour-surface);
    border-bottom: 1px solid var(--colour-border);
    box-shadow: var(--shadow-lg);
    padding: 0;
    gap: 0;
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
  }

  .header__nav.is-open .header__nav-link {
    display: block;
    padding: var(--space-3) var(--space-5);
    font-size: var(--text-base);
    text-align: left;
    border-bottom: 1px solid var(--colour-border-light);
  }

  .header__nav.is-open .header__dropdown {
    border-bottom: 1px solid var(--colour-border-light);
  }

  .header__nav.is-open .header__dropdown-toggle {
    display: flex;
    align-items: stretch;
    width: 100%;
  }

  .header__nav.is-open .header__dropdown-link {
    flex: 1;
    border-bottom: none;
  }

  .header__nav.is-open .header__dropdown-chevron {
    padding: var(--space-3) var(--space-5);
  }

  .header__nav.is-open .header__dropdown.is-open .header__dropdown-arrow {
    transform: rotate(180deg);
  }

  .header__nav.is-open .header__dropdown.is-open .header__dropdown-chevron:hover .header__dropdown-arrow {
    transform: rotate(0deg);
  }

  .header__nav.is-open .header__dropdown-menu {
    position: static;
    display: none;
    opacity: 1;
    visibility: visible;
    transform: none;
    box-shadow: none;
    border: none;
    border-radius: 0;
    margin-top: 0;
    padding: 0;
    background-color: var(--colour-bg-secondary);
  }

  .header__nav.is-open .header__dropdown.is-open .header__dropdown-menu {
    display: block;
  }

  .header__nav.is-open .header__dropdown-item {
    padding: var(--space-3) var(--space-5) var(--space-3) var(--space-8);
  }

  .header__menu-toggle {
    display: flex;
  }
}

/* --------------------------------------------------------------------------
   Mobile Navigation Drawer
   -------------------------------------------------------------------------- */

.nav-drawer {
  position: fixed;
  inset: 0;
  z-index: var(--z-overlay);
  display: none;
}

.nav-drawer.is-open {
  display: block;
}

.nav-drawer__overlay {
  position: absolute;
  inset: 0;
  background-color: var(--colour-overlay);
}

.nav-drawer__panel {
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: min(20rem, 80vw);
  background-color: var(--colour-surface);
  padding: var(--space-6);
  overflow-y: auto;
}

.nav-drawer__link {
  display: block;
  padding: var(--space-3) 0;
  font-size: var(--text-md);
  font-weight: var(--weight-medium);
  color: var(--colour-text);
  border-bottom: 1px solid var(--colour-border-light);
  transition: color var(--transition-fast);
}

.nav-drawer__link:hover {
  color: var(--colour-accent);
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */

.footer {
  width: 100%;
  background-color: var(--colour-chrome);
  border-top: 1px solid var(--colour-border);
  padding: var(--space-12) 0 var(--space-8);
}

.footer__inner {
  max-width: var(--content-width);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.footer__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr));
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer__heading {
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--colour-text);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wider);
  margin-bottom: var(--space-4);
}

.footer__link {
  display: block;
  padding: var(--space-1) 0;
  font-size: var(--text-sm);
  color: var(--colour-text-secondary);
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: var(--colour-accent);
}

.footer__text {
  font-size: var(--text-sm);
  color: var(--colour-text-tertiary);
  line-height: var(--leading-relaxed);
}

.footer__bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-8);
  border-top: 1px solid var(--colour-border);
  font-size: var(--text-sm);
  color: var(--colour-text-tertiary);
}

.footer__theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: 1px solid var(--colour-border);
  border-radius: var(--radius-md);
  padding: var(--space-2);
  color: var(--colour-text-tertiary);
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.footer__theme-toggle:hover {
  color: var(--colour-text-primary);
  border-color: var(--colour-text-tertiary);
}

.footer__theme-toggle svg {
  width: 1.125rem;
  height: 1.125rem;
}

.footer--minimal {
  padding: var(--space-6) 0;
}

.footer--minimal .footer__bottom {
  padding-top: 0;
  border-top: none;
}

/* --------------------------------------------------------------------------
   Two-Column Layout (e.g. sidebar + content)
   -------------------------------------------------------------------------- */

.layout-sidebar {
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr;
  min-height: calc(100dvh - var(--header-height));
}

@media (max-width: 64em) {
  .layout-sidebar {
    grid-template-columns: 1fr;
  }
}

/* --------------------------------------------------------------------------
   Section Spacing
   -------------------------------------------------------------------------- */

.section {
  padding: var(--space-16) 0;
}

.section--sm {
  padding: var(--space-8) 0;
}

.section--lg {
  padding: var(--space-24) 0;
}

/* --------------------------------------------------------------------------
   Theme Toggle Icon Visibility
   Shows only the icon matching the current theme state via data attribute.
   -------------------------------------------------------------------------- */

.theme-icon { display: none; }

[data-current-theme="light"] .theme-icon--light,
[data-current-theme="dark"] .theme-icon--dark,
[data-current-theme="bsb"] .theme-icon--bsb,
[data-current-theme="system"] .theme-icon--system {
  display: block;
}

/* Default: show system icon before JS sets state */
#js-theme-cycle:not([data-current-theme]) .theme-icon--system {
  display: block;
}