/* =============================================================================
   HEADER — Glassmorphism sticky header
   ============================================================================= */

/* ---------------------------------------------------------------------------
   READING PROGRESS BAR
--------------------------------------------------------------------------- */

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: var(--gradient-accent);
  z-index: calc(var(--z-sticky) + 1);
  transition: width 0.1s linear;
  border-radius: 0 var(--radius-full) var(--radius-full) 0;
  pointer-events: none;
}

/* ---------------------------------------------------------------------------
   SITE HEADER
--------------------------------------------------------------------------- */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-sticky);
  height: var(--header-height);
  transition: height var(--transition-base);
}

.site-header__inner {
  height: 100%;
  background: var(--header-bg);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border-bottom: 1px solid var(--header-border);
  box-shadow: var(--shadow-header);
  transition: background var(--transition-base), box-shadow var(--transition-base);
}

/* Scrolled state (JS adds .is-scrolled) */
.site-header.is-scrolled {
  height: var(--header-height-scroll);
}

.site-header.is-scrolled .site-header__inner {
  background: rgba(248, 250, 255, 0.97);
  box-shadow: 0 2px 30px rgba(15, 23, 42, 0.1);
}

/* Dark mode — OS preference */
@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) .site-header__inner {
    background: rgba(11, 15, 26, 0.85);
    border-bottom-color: rgba(30, 41, 59, 0.8);
  }
  html:not([data-theme="light"]) .site-header.is-scrolled .site-header__inner {
    background: rgba(11, 15, 26, 0.97);
    box-shadow: 0 2px 30px rgba(0, 0, 0, 0.3);
  }
}

/* Dark mode — manual toggle */
html[data-theme="dark"] .site-header__inner {
  background: rgba(11, 15, 26, 0.85);
  border-bottom-color: rgba(30, 41, 59, 0.8);
}
html[data-theme="dark"] .site-header.is-scrolled .site-header__inner {
  background: rgba(11, 15, 26, 0.97);
  box-shadow: 0 2px 30px rgba(0, 0, 0, 0.3);
}

/* Light mode — force light even on dark OS */
html[data-theme="light"] .site-header__inner {
  background: var(--header-bg);
  border-bottom-color: var(--header-border);
}
html[data-theme="light"] .site-header.is-scrolled .site-header__inner {
  background: rgba(248, 250, 255, 0.97);
  box-shadow: 0 2px 30px rgba(15, 23, 42, 0.1);
}

/* ---------------------------------------------------------------------------
   HEADER ROW
--------------------------------------------------------------------------- */

.site-header__row {
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
  transition: height var(--transition-base);
}

.site-header.is-scrolled .site-header__row {
  height: var(--header-height-scroll);
}

/* ---------------------------------------------------------------------------
   SITE BRANDING
--------------------------------------------------------------------------- */

.site-header__branding {
  flex-shrink: 0;
}

/* The block--system-branding-block template handles inner markup */
.site-branding {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
}

.site-branding__logo img {
  height: 40px;
  width: auto;
}

.site-branding__name {
  font-family: var(--font-sans);
  font-size: var(--text-lg);
  font-weight: var(--font-bold);
  line-height: 1;
  letter-spacing: var(--tracking-tight);
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.site-branding__slogan {
  display: block;
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  letter-spacing: var(--tracking-wide);
  -webkit-text-fill-color: var(--color-text-muted);
}

/* ---------------------------------------------------------------------------
   MOBILE NAV TOGGLE BUTTON
--------------------------------------------------------------------------- */

.mobile-nav-button {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-2);
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.mobile-nav-button:hover {
  background: var(--color-brand-subtle);
  border-color: var(--color-border-brand);
  color: var(--color-brand-text);
}

/* Hide text label — icon only */
.mobile-nav-button__label {
  display: none;
}

/* Hamburger bars */
.mobile-nav-button__bars {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  width: 20px;
  height: 14px;
}

.mobile-nav-button__bars span {
  display: block;
  width: 100%;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: all var(--transition-fast);
}

/* Animate to X when open */
.mobile-nav-button[aria-expanded="true"] .mobile-nav-button__bars span:nth-child(1) {
  transform: translateY(5.5px) rotate(45deg);
}
.mobile-nav-button[aria-expanded="true"] .mobile-nav-button__bars span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}
.mobile-nav-button[aria-expanded="true"] .mobile-nav-button__bars span:nth-child(3) {
  transform: translateY(-5.5px) rotate(-45deg);
}

@media (min-width: 1024px) {
  .mobile-nav-button {
    display: none;
  }
}

/* ---------------------------------------------------------------------------
   NAV OVERLAY (mobile backdrop)
--------------------------------------------------------------------------- */

.nav-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.5);
  backdrop-filter: blur(4px);
  z-index: calc(var(--z-sticky) - 1);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.nav-overlay.is-active {
  opacity: 1;
  pointer-events: auto;
}

/* ---------------------------------------------------------------------------
   HEADER SEARCH
--------------------------------------------------------------------------- */

.header-search {
  position: relative;
  flex-shrink: 0;
}

.header-search__btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.header-search__btn:hover,
.header-search__btn[aria-expanded="true"] {
  background: var(--color-brand-subtle);
  border-color: var(--color-border-brand);
  color: var(--color-brand-text);
}

/* ---------------------------------------------------------------------------
   SEARCH PANEL — Full-width slide-down panel (sibling of <header>)
--------------------------------------------------------------------------- */

.search-panel {
  position: fixed;
  top: var(--header-height-current, var(--header-height));
  left: 0;
  right: 0;
  width: 100%;
  max-height: calc(100vh - var(--header-height-current, var(--header-height)));
  overflow-y: auto;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: 0 8px 32px rgba(15, 23, 42, 0.12);
  z-index: calc(var(--z-sticky) - 1);
  padding: var(--space-5) 0 var(--space-8);
  transform: translateY(-110%);
  opacity: 0;
  visibility: hidden;
  transition:
    transform  var(--transition-base),
    opacity    var(--transition-base),
    visibility var(--transition-base);
}

.search-panel.is-open {
  transform: translateY(0);
  opacity: 1;
  visibility: visible;
}

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

.search-panel__cse {
  flex: 1;
  min-width: 0;
}

.search-panel__close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-full);
  border: 1.5px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  cursor: pointer;
  flex-shrink: 0;
  transition: all var(--transition-fast);
}

.search-panel__close:hover {
  background: var(--color-brand-subtle);
  border-color: var(--color-border-brand);
  color: var(--color-brand-text);
}

/* Dark theme */
html[data-theme="dark"] .search-panel {
  background: rgba(11, 15, 26, 0.97);
  border-bottom-color: rgba(30, 41, 59, 0.8);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

html[data-theme="dark"] .search-panel__close {
  background: rgba(30, 41, 59, 0.6);
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) .search-panel {
    background: rgba(11, 15, 26, 0.97);
    border-bottom-color: rgba(30, 41, 59, 0.8);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  }
}