/**
 * ============================================================================
 * header.css — .site-header BEM Block
 * ============================================================================
 *
 * Mobile: compact bar, logo + name only (.site-header__desktop hidden).
 * Desktop: sticky; transparent at top, solid navy after scroll.
 *
 * ============================================================================
 */

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  padding: var(--space-md) 0;
  transition: background-color var(--transition-default), color var(--transition-default);
}

/* Default (top of page): transparent, content flows behind; text readable on page bg */
.site-header {
  background-color: transparent;
  color: var(--color-text);
}

/* Transparent header: use theme text colour so logo is readable in light and dark mode */
.site-header .site-header__brand {
  color: var(--color-text);
}

.site-header .site-header__brand:hover,
.site-header .site-header__brand:focus-visible {
  color: var(--color-text);
  opacity: 0.85;
}

.site-header .site-header__logo {
  opacity: 0.9;
}

.site-header .site-header__tagline {
  color: var(--color-text-muted);
}

/* Scrolled: solid navy bar (desktop-style) */
.site-header.site-header--scrolled {
  background-color: var(--color-primary);
  color: var(--color-on-primary);
}

.site-header.site-header--scrolled .site-header__brand,
.site-header.site-header--scrolled .site-header__brand:hover,
.site-header.site-header--scrolled .site-header__brand:focus-visible {
  color: var(--color-on-primary);
}

.site-header.site-header--scrolled .site-header__tagline {
  color: var(--color-on-primary-subtle);
}

/* Mobile: always solid so logo is visible on any background */
@media (max-width: 767px) {
  .site-header {
    background-color: var(--color-primary);
    color: var(--color-on-primary);
  }

  .site-header .site-header__brand,
  .site-header .site-header__brand:hover,
  .site-header .site-header__brand:focus-visible {
    color: var(--color-on-primary);
  }

  .site-header .site-header__tagline {
    color: var(--color-on-primary-subtle);
  }
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.site-header__brand {
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.site-header__brand:hover,
.site-header__brand:focus-visible {
  text-decoration: none;
}

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

.site-header__brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.site-header__brand-name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-bold);
  letter-spacing: -0.01em;
}

.site-header__tagline {
  font-size: var(--text-xs);
  display: none;
}

/* Desktop: show nav + theme toggle */
.site-header__desktop {
  display: none;
}

@media (min-width: 768px) {
  .site-header__tagline {
    display: inline;
  }

  .site-header__desktop {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    flex-wrap: wrap;
  }

  /* Theme toggle in header: when transparent use surface/text colours */
  .site-header:not(.site-header--scrolled) .theme-toggle__button {
    background-color: var(--color-surface);
    color: var(--color-text);
    border-color: var(--color-border);
  }

  .site-header:not(.site-header--scrolled) .theme-toggle__button:hover,
  .site-header:not(.site-header--scrolled) .theme-toggle__button:focus-visible {
    background-color: var(--color-border);
  }

  .site-header:not(.site-header--scrolled) .theme-toggle__button:focus-visible {
    border-color: var(--color-text);
  }

  /* Keep header content on one row; nav can scroll horizontally if needed */
  .site-header__inner {
    flex-wrap: nowrap;
  }

  .site-header__desktop {
    flex-wrap: nowrap;
    min-width: 0;
    flex: 1;
    justify-content: flex-end;
  }
}