/* Header layout & branding */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: radial-gradient(circle at top, rgba(15, 23, 42, 0.98) 0, rgba(5, 8, 22, 0.98) 60%, rgba(5, 8, 22, 0.98) 100%);
  border-bottom: 1px solid rgba(148, 163, 184, 0.25);
  backdrop-filter: blur(14px);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: var(--space-3);
  gap: var(--space-4);
}

.site-header__branding {
  display: flex;
  align-items: center;
  min-width: 0;
}

.site-header__logo-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
}

.site-header__logo-mark {
  width: 2.3rem;
  height: 2.3rem;
  border-radius: var(--radius-full);
  background: conic-gradient(from 210deg, var(--color-primary), var(--color-accent-red), var(--color-accent-green), var(--color-accent-blue), var(--color-primary));
  padding: 2px;
}

.site-header__logo-mark::before {
  content: "";
  display: block;
  width: 100%;
  height: 100%;
  border-radius: inherit;
  background: radial-gradient(circle at 30% 20%, rgba(255, 255, 255, 0.42) 0, transparent 32%),
              radial-gradient(circle at 70% 80%, rgba(15, 23, 42, 0.95) 0, rgba(15, 23, 42, 1) 52%);
}

.site-header__title-group {
  display: flex;
  flex-direction: column;
}

.site-header__site-name {
  font-family: var(--font-display);
  font-size: var(--font-size-base);
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  white-space: nowrap;
}

.site-header__tagline {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

/* Navigation */
.site-header__nav {
  display: flex;
}

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

.site-header__nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  padding-block: 0.15rem;
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.site-header__nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -0.3rem;
  height: 2px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent-green));
  transform: scaleX(0);
  transform-origin: center;
  transition: transform var(--transition-fast);
}

.site-header__nav-link:hover,
.site-header__nav-link:focus-visible {
  color: var(--color-text);
}

.site-header__nav-link:hover::after,
.site-header__nav-link:focus-visible::after {
  transform: scaleX(1);
}

.site-header__nav-link--button {
  padding-inline: var(--space-4);
  padding-block: 0.4rem;
  border-radius: var(--radius-full);
  border: 1px solid rgba(251, 191, 36, 0.7);
  background: radial-gradient(circle at top left, rgba(251, 191, 36, 0.25), transparent 55%),
              rgba(15, 23, 42, 0.98);
  color: var(--color-primary);
  font-weight: 500;
  box-shadow: var(--shadow-sm);
}

.site-header__nav-link--button::after {
  display: none;
}

.site-header__nav-link--button:hover,
.site-header__nav-link--button:focus-visible {
  border-color: var(--color-primary);
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-strong));
  color: #111827;
}

.site-header__nav-item--cta {
  margin-left: var(--space-2);
}

/* Mobile menu toggle */
.site-header__menu-toggle {
  display: none;
  align-items: center;
  gap: var(--space-2);
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius-full);
  border: 1px solid rgba(148, 163, 184, 0.5);
  background-color: rgba(15, 23, 42, 0.92);
  color: var(--color-text);
  cursor: pointer;
}

.site-header__menu-toggle-box {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 0.18rem;
}

.site-header__menu-toggle-line {
  width: 1.1rem;
  height: 2px;
  border-radius: 999px;
  background-color: var(--color-gray-300);
  transition: transform var(--transition-fast), opacity var(--transition-fast), translate var(--transition-fast);
}

.site-header__menu-toggle-text {
  font-size: var(--font-size-xs);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

/* Open state (class toggled via JS) */
.site-header__menu-toggle[aria-expanded="true"] .site-header__menu-toggle-line:nth-child(1) {
  transform: rotate(45deg) translate(3px, 3px);
}

.site-header__menu-toggle[aria-expanded="true"] .site-header__menu-toggle-line:nth-child(2) {
  opacity: 0;
}

.site-header__menu-toggle[aria-expanded="true"] .site-header__menu-toggle-line:nth-child(3) {
  transform: rotate(-45deg) translate(3px, -3px);
}

/* Responsive behaviour */
@media (max-width: 900px) {
  .site-header__inner {
    padding-block: var(--space-3);
  }

  .site-header__tagline {
    display: none;
  }

  .site-header__nav-item--cta {
    margin-left: 0;
  }
}

@media (max-width: 768px) {
  .site-header__menu-toggle {
    display: inline-flex;
  }

  .site-header__nav {
    position: fixed;
    inset-inline: 0;
    top: 3.4rem;
    background: radial-gradient(circle at top, rgba(15, 23, 42, 0.98) 0, rgba(5, 8, 22, 0.98) 60%);
    border-bottom: 1px solid rgba(148, 163, 184, 0.25);
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--transition-normal), opacity var(--transition-normal);
  }

  .site-header__nav-list {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-4) var(--layout-gutter) var(--space-5);
    gap: var(--space-3);
  }

  .site-header__nav-link {
    font-size: var(--font-size-base);
  }

  .site-header__nav-link::after {
    bottom: -0.2rem;
  }

  .site-header__nav-link--button {
    width: 100%;
    justify-content: center;
  }

  .site-header__nav--open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
}

@media (max-width: 480px) {
  .site-header__site-name {
    font-size: var(--font-size-sm);
  }
}