/* Header layout & branding */
.header {
  position: sticky;
  top: 0;
  z-index: 50;
}

.header__inner {
  gap: var(--space-4);
}

.header__brand {
  display: flex;
  align-items: center;
}

.header__logo-link {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--gray-900);
}

.header__logo-mark {
  width: 2.4rem;
  height: 2.4rem;
  border-radius: var(--radius-full);
  background: radial-gradient(circle at 20% 20%, var(--color-accent-green) 0, var(--color-primary) 40%, var(--color-primary-strong) 100%);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 1.1rem;
  box-shadow: var(--shadow-md);
}

.header__text-group {
  display: flex;
  flex-direction: column;
}

.header__site-name {
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-size: 0.86rem;
}

.header__tagline {
  font-size: 0.78rem;
  color: var(--color-text-muted);
}

/* Navigation */
.header__nav {
  margin-left: auto;
}

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

.header__nav-link {
  font-size: var(--font-size-sm);
  color: var(--gray-700);
  padding: 0.25rem 0;
}

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

.header__nav-item--highlight .header__nav-link--button {
  padding: 0.45rem 1.1rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-primary-soft);
  background-color: #ffffff;
  box-shadow: var(--shadow-sm);
  color: var(--color-primary-strong);
  font-weight: 500;
}

.header__nav-item--highlight .header__nav-link--button:hover,
.header__nav-item--highlight .header__nav-link--button:focus-visible {
  background-color: var(--color-primary);
  color: #ffffff;
  border-color: var(--color-primary);
}

/* Mobile menu toggle */
.header__menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 0.25rem;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--gray-200);
  background-color: #ffffff;
  cursor: pointer;
}

.header__menu-toggle-bar {
  width: 1.3rem;
  height: 2px;
  border-radius: 999px;
  background-color: var(--gray-800);
  transition: transform var(--transition-fast), opacity var(--transition-fast), background-color var(--transition-fast);
}

.header__menu-toggle:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}

/* Hamburger to close icon animation */
.header__menu-toggle[aria-expanded="true"] .header__menu-toggle-bar:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

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

.header__menu-toggle[aria-expanded="true"] .header__menu-toggle-bar:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* Responsive behaviour */
@media (max-width: 900px) {
  .header__menu-toggle {
    display: inline-flex;
  }

  .header__nav {
    position: absolute;
    inset-inline: 0;
    top: 100%;
    background-color: #ffffff;
    box-shadow: 0 12px 30px rgba(15, 23, 42, 0.12);
    border-bottom: 1px solid var(--gray-200);
    max-height: 0;
    overflow: hidden;
    visibility: hidden;
    opacity: 0;
    transition: max-height var(--transition-slow), opacity var(--transition-normal), visibility var(--transition-normal);
  }

  .header__nav-list {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-4) var(--container-padding-x);
    gap: var(--space-3);
  }

  .header__nav-item--highlight .header__nav-link--button {
    width: 100%;
    text-align: center;
  }

  .header__nav--open {
    visibility: visible;
    opacity: 1;
    max-height: 420px;
  }
}

@media (max-width: 480px) {
  .header__site-name {
    font-size: 0.8rem;
  }

  .header__tagline {
    display: none;
  }
}

/* Desktop refinements */
@media (min-width: 901px) {
  .header__nav {
    position: static;
    opacity: 1;
    visibility: visible;
    max-height: none;
    box-shadow: none;
    border-bottom: none;
  }
}