/* ==========================================================================
   layout.css — Kai-Signals: structural layout
   Header · Footer · Nav · Container · Skip-link · Language switch
   ========================================================================== */

/* ── Container ───────────────────────────────────────────────────────────── */
.container {
  max-width: var(--container-max);
  width: 100%;
  margin-inline: auto;
  padding-inline: var(--side-padding-desktop);
}

.container--narrow {
  max-width: var(--container-narrow);
  width: 100%;
  margin-inline: auto;
  padding-inline: var(--side-padding-desktop);
}

.container--wide {
  max-width: var(--container-wide);
  width: 100%;
  margin-inline: auto;
  padding-inline: var(--side-padding-desktop);
}

@media (max-width: 1023px) {
  .container, .container--narrow, .container--wide {
    padding-inline: var(--side-padding-mobile);
  }
}

/* ── Skip link ───────────────────────────────────────────────────────────── */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  z-index: 9999;
  background-color: var(--color-brand-teal);
  color: #fff;
  padding: var(--space-3) var(--space-5);
  border-radius: 0 0 var(--radius-btn) var(--radius-btn);
  font-weight: 600;
  font-size: var(--text-label-size);
  text-decoration: none;
  transition: top var(--duration-fast);
}

.skip-link:focus {
  top: 0;
  outline: 2px solid var(--color-navy-base);
  outline-offset: 2px;
}

/* ── Site header ─────────────────────────────────────────────────────────── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--nav-bg);
  border-bottom: 1px solid var(--nav-border);
  transition: background-color var(--duration-default) var(--easing-default),
              box-shadow var(--duration-default) var(--easing-default),
              border-color var(--duration-default) var(--easing-default);
}

/* JS adds .scrolled when window.scrollY > 10 */
.site-header.scrolled {
  background-color: color-mix(in srgb, var(--nav-bg) 95%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 var(--surface-border);
}

.site-header__inner {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  height: 64px;
}

/* ── Brand ───────────────────────────────────────────────────────────────── */
.site-header__brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  flex-shrink: 0;
  transition: opacity var(--duration-fast);
}

.site-header__brand:hover { opacity: 0.8; color: var(--text-primary); }

.site-header__brand span { color: var(--color-brand-teal); }

.site-header__logo {
  height: 40px;
  width: auto;
  display: block;
  color: var(--text-primary);
}

/* Show/hide logo variants based on active theme.
   Default (no cookie, OS-light or OS-dark): dark variant always shown at first paint.
   JS FOUC script always sets data-theme, so these rules cover all states. */
:root[data-theme="light"] .site-header__logo--dark  { display: none; }
:root[data-theme="light"] .site-header__logo--light { display: block; }
:root[data-theme="dark"]  .site-header__logo--light { display: none; }
:root[data-theme="dark"]  .site-header__logo--dark  { display: block; }

/* Fallback for OS dark preference before JS runs (no cookie) */
@media (prefers-color-scheme: dark) {
  .site-header__logo--light { display: none; }
  .site-header__logo--dark  { display: block; }
}
@media (prefers-color-scheme: light) {
  .site-header__logo--dark  { display: none; }
  .site-header__logo--light { display: block; }
}

/* ── Primary nav ─────────────────────────────────────────────────────────── */
.site-nav {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  flex: 1;
}

.site-nav__link {
  font-family: var(--font-body);
  font-size: var(--text-label-size);
  font-weight: 500;
  color: var(--nav-text-muted);
  text-decoration: none;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-btn);
  transition: color var(--duration-fast) var(--easing-default),
              background-color var(--duration-fast) var(--easing-default);
  white-space: nowrap;
  position: relative;
}

.site-nav__link:hover {
  color: var(--nav-text);
  background-color: var(--surface-raised);
}

.site-nav__link.active,
.site-nav__link[aria-current="page"] {
  color: var(--text-brand);
  font-weight: 600;
}

/* Active underline indicator */
.site-nav__link.active::after,
.site-nav__link[aria-current="page"]::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: var(--space-3);
  right: var(--space-3);
  height: 2px;
  background-color: var(--color-brand-teal);
  border-radius: 1px;
}

/* ── Header actions (language switch + theme toggle + CTAs) ──────────────── */
.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-left: auto;
}

.site-header__actions .logout-form { display: inline; }

/* ── Header CTAs ─────────────────────────────────────────────────────────── */
.site-header__cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-family: var(--font-body);
  font-size: var(--text-label-size);
  font-weight: 600;
  line-height: 1;
  padding: 10px var(--space-5);
  border-radius: var(--radius-btn);
  text-decoration: none;
  white-space: nowrap;
  transition: background-color var(--duration-fast) var(--easing-default),
              border-color var(--duration-fast) var(--easing-default),
              color var(--duration-fast) var(--easing-default),
              transform var(--duration-fast) var(--easing-default),
              box-shadow var(--duration-fast) var(--easing-default);
}

.site-header__cta--secondary {
  background-color: transparent;
  border: 1px solid var(--btn-secondary-border);
  color: var(--btn-secondary-text);
}

.site-header__cta--secondary:hover {
  background-color: var(--btn-secondary-bg-hover);
  color: var(--btn-secondary-text);
  transform: translateY(-1px);
}

.site-header__cta--primary {
  background-color: var(--btn-primary-bg);
  border: 1px solid transparent;
  color: var(--btn-primary-text);
  box-shadow: 0 1px 2px rgb(0 0 0 / 0.12);
}

.site-header__cta--primary:hover {
  background-color: var(--btn-primary-bg-hover);
  color: var(--btn-primary-text);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px color-mix(in srgb, var(--color-brand-teal) 30%, transparent);
}

.site-header__cta--primary:active,
.site-header__cta--secondary:active {
  transform: translateY(0);
  box-shadow: none;
}

/* ── Theme toggle button ─────────────────────────────────────────────────── */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-btn);
  border: 1px solid var(--surface-border);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: color var(--duration-fast),
              background-color var(--duration-fast),
              border-color var(--duration-fast);
  flex-shrink: 0;
}

.theme-toggle:hover {
  background-color: var(--surface-raised);
  color: var(--text-primary);
  border-color: var(--color-brand-teal);
}

.theme-toggle svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.5;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform var(--duration-default) var(--easing-default);
}

.theme-toggle:hover svg { transform: rotate(20deg); }

/* Show/hide sun vs moon icon based on current theme */
.theme-toggle .icon-sun  { display: none; }
.theme-toggle .icon-moon { display: block; }

[data-theme="dark"] .theme-toggle .icon-sun  { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

@media (prefers-color-scheme: dark) {
  :not([data-theme="light"]) .theme-toggle .icon-sun  { display: block; }
  :not([data-theme="light"]) .theme-toggle .icon-moon { display: none; }
}

/* ── Hamburger button (mobile) ───────────────────────────────────────────── */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 36px;
  height: 36px;
  gap: 5px;
  background: transparent;
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-btn);
  cursor: pointer;
  padding: 0;
  color: var(--text-primary);
  transition: border-color var(--duration-fast);
  flex-shrink: 0;
}

.hamburger:hover { border-color: var(--color-brand-teal); }

.hamburger__bar {
  display: block;
  width: 18px;
  height: 1.5px;
  background-color: currentColor;
  border-radius: 1px;
  transition: transform var(--duration-default) var(--easing-default),
              opacity var(--duration-fast) var(--easing-default),
              width var(--duration-default) var(--easing-default);
  transform-origin: center;
}

/* Animate to X when [aria-expanded="true"] */
.hamburger[aria-expanded="true"] .hamburger__bar:nth-child(1) {
  transform: translateY(6.5px) rotate(45deg);
}
.hamburger[aria-expanded="true"] .hamburger__bar:nth-child(2) {
  opacity: 0;
  width: 0;
}
.hamburger[aria-expanded="true"] .hamburger__bar:nth-child(3) {
  transform: translateY(-6.5px) rotate(-45deg);
}

/* ── Mobile nav drawer ───────────────────────────────────────────────────── */
.site-nav__drawer {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background-color: var(--nav-bg);
  border-bottom: 1px solid var(--nav-border);
  overflow: hidden;
  max-height: 0;
  transition: max-height var(--duration-slow) var(--easing-default);
  box-shadow: 0 8px 24px rgb(0 0 0 / 0.12);
}

.site-nav__drawer.open {
  max-height: 600px;
}

.site-nav__drawer-inner {
  display: flex;
  flex-direction: column;
  padding: var(--space-4) var(--side-padding-mobile);
  gap: var(--space-2);
}

.site-nav__drawer .site-nav__link {
  padding: var(--space-3) var(--space-2);
  font-size: var(--text-body-md-size);
  border-bottom: 1px solid var(--surface-border);
}

.site-nav__drawer .site-nav__link:last-child { border-bottom: none; }

.site-nav__drawer-actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-2) var(--space-2);
}

/* ── Site main ───────────────────────────────────────────────────────────── */
.site-main {
  flex: 1;
  display: flex;
  flex-direction: column;
}

/* ── Site footer ─────────────────────────────────────────────────────────── */
.site-footer {
  background-color: var(--surface-raised);
  border-top: 1px solid var(--surface-border);
  padding-block: var(--space-8);
  margin-top: auto;
}

.site-footer__inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
  text-align: center;
}

.site-footer__nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-2) var(--space-4);
}

.site-footer__nav a,
.site-footer__link-button {
  font-family: var(--font-body);
  font-size: var(--text-body-sm-size);
  color: var(--text-tertiary);
  text-decoration: none;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0;
  transition: color var(--duration-fast);
}

.site-footer__nav a:hover,
.site-footer__link-button:hover {
  color: var(--text-brand);
}

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

/* ── Responsive: collapse nav at <lg ─────────────────────────────────────── */
@media (max-width: 1023px) {
  .site-nav { display: none; }
  .hamburger { display: flex; }
  .site-nav__drawer { display: block; }
  .site-header__cta { display: none; }

  .site-header__inner {
    height: 56px;
  }

  .site-header__actions {
    gap: var(--space-2);
  }
}

@media (max-width: 479px) {
  .language-switch { display: none; } /* hidden; language shown in drawer */
}