/* ===========================================
   FLOWBRAIN — Header / Navbar
   =========================================== */

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-header);
  padding: 20px 0;
  transition: padding 0.4s ease, background 0.4s ease;
  background: transparent;
}

.header.is-scrolled {
  padding: 12px 0;
  background: rgba(5, 5, 16, 0.8);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.header__logo {
  font-family: var(--font-display);
  font-size: 1.375rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--color-white);
  z-index: calc(var(--z-overlay) + 1);
}

.header__logo span {
  color: var(--color-accent);
}

.header__nav {
  display: flex;
  align-items: center;
  gap: 36px;
}

.header__link {
  font-size: 0.8125rem;
  font-weight: 500;
  color: rgba(255,255,255,0.65);
  transition: color var(--duration-fast) ease;
}

.header__link:hover,
.header__link.is-active {
  color: var(--color-white);
}

.header__cta {
  margin-left: 20px;
}

/* Hamburger */
.header__hamburger {
  display: none;
  flex-direction: column;
  gap: 6px;
  width: 28px;
  padding: 4px 0;
  z-index: calc(var(--z-overlay) + 1);
}

.header__hamburger span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-white);
  transition: all var(--duration-fast) ease;
  transform-origin: center;
}

.header__hamburger.is-open span:nth-child(1) { transform: translateY(8px) rotate(45deg); }
.header__hamburger.is-open span:nth-child(2) { opacity: 0; }
.header__hamburger.is-open span:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }

/* Mobile menu */
.header__mobile-menu {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100dvh;
  background: rgba(5, 5, 16, 0.97);
  z-index: var(--z-overlay);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 32px;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.4s ease, visibility 0.4s ease;
}

.header__mobile-menu.is-open {
  opacity: 1;
  visibility: visible;
}

.header__mobile-link {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  color: rgba(255,255,255,0.6);
  transition: color var(--duration-fast) ease;
}

.header__mobile-link:hover {
  color: var(--color-white);
}

.header__mobile-cta {
  margin-top: 24px;
}