/* ============================================================
   Site header — sticky, white, identity left, nav right
   ============================================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: var(--color-header-bg);
  border-bottom: var(--border-thin);
  box-shadow: var(--shadow-sticky);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 12px var(--page-margin);
}

/* === Identity block (left) === */
.site-header__identity {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  text-decoration: none;
}

.site-header__identity:hover .identity__name { color: var(--color-accent); }

.identity__name {
  font-family: var(--font-display);
  font-size: var(--fs-name);
  font-weight: var(--fw-bold);
  line-height: var(--lh-tight);
  color: var(--color-header-text);
  transition: color var(--transition-fast);
  white-space: nowrap;
}

.identity__sub {
  font-family: var(--font-body);
  font-size: var(--fs-name-sub);
  font-weight: var(--fw-regular);
  color: var(--color-text-muted);
  line-height: var(--lh-snug);
}

.identity__meta {
  font-family: var(--font-body);
  font-size: var(--fs-name-meta);
  font-weight: var(--fw-regular);
  color: var(--color-text-light);
  line-height: var(--lh-snug);
}

/* === Desktop nav (right) === */
.site-nav { flex-shrink: 0; }

.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.site-nav__list a {
  position: relative;
  font-family: var(--font-body);
  font-size: var(--fs-nav);
  font-weight: var(--fw-medium);
  color: var(--color-header-nav);
  padding: 4px 0;
  transition: color var(--transition-fast);
  white-space: nowrap;
}

.site-nav__list a::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 100%;
  height: 2px;
  background: var(--color-accent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--transition-base);
}

.site-nav__list a:hover { color: var(--color-text); }
.site-nav__list a:hover::after,
.site-nav__list a.active::after { transform: scaleX(1); }
.site-nav__list a.active { color: var(--color-text); }

/* === Hamburger (mobile only) === */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  width: 36px;
  height: 36px;
  padding: 8px;
  flex-shrink: 0;
}

.hamburger__line {
  display: block;
  width: 100%;
  height: 1px;
  background: var(--color-header-text);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

/* === Mobile full-screen menu overlay === */
.mobile-nav {
  position: fixed;
  inset: 0;
  z-index: var(--z-overlay);
  background: var(--color-white);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.mobile-nav.open {
  opacity: 1;
  pointer-events: auto;
}

.mobile-nav[hidden] { display: none; }

.mobile-nav__close {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  width: 44px;
  height: 44px;
  font-size: 2rem;
  line-height: 1;
  color: var(--color-text);
}

.mobile-nav__list {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
  text-align: center;
}

.mobile-nav__list a {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: var(--fw-bold);
  color: var(--color-text);
  padding: var(--space-sm) var(--space-md);
  transition: color var(--transition-fast);
}

.mobile-nav__list a:hover,
.mobile-nav__list a.active { color: var(--color-accent); }

/* === Responsive === */
@media (max-width: 900px) {
  .site-nav__list { gap: var(--space-md); }
}

@media (max-width: 767px) {
  .identity__sub, .identity__meta { display: none; }
  .site-nav { display: none; }
  .hamburger { display: flex; }
}