.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-height);
  background-color: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid rgba(255, 255, 255, 0.04);
  transition: all var(--duration-normal) var(--ease-default);
}

.site-header.is-scrolled {
  background-color: rgba(10, 10, 15, 0.95);
  border-bottom-color: rgba(255, 255, 255, 0.06);
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.4);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

/* ── Logo ── */
.site-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-heading);
  font-size: var(--fs-lg);
  font-weight: var(--fw-bold);
  color: var(--color-white);
  letter-spacing: -0.02em;
}

.site-logo__mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-hover) 100%);
  border-radius: var(--radius-md);
  font-weight: var(--fw-extrabold);
  font-size: var(--fs-sm);
  color: var(--color-black);
  letter-spacing: 0;
}

.site-logo img {
  height: 36px;
  width: auto;
}

/* ── Navigation ── */
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.nav-links a {
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--color-gray);
  transition: color var(--duration-fast) var(--ease-default);
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-light));
  transition: width var(--duration-normal) var(--ease-default);
  border-radius: 1px;
}

.nav-links a:hover {
  color: var(--color-white);
}

.nav-links a:hover::after {
  width: 100%;
}

.nav-cta {
  margin-left: var(--space-md);
}

/* ── Mobile Menu Toggle ── */
.menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 28px;
  height: 28px;
  padding: 0;
}

.menu-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--color-white);
  border-radius: 2px;
  transition: all var(--duration-normal) var(--ease-default);
  transform-origin: center;
}

.menu-toggle.is-active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.menu-toggle.is-active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.is-active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Mobile Nav ── */
.mobile-nav {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(10, 10, 15, 0.98);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: var(--space-2xl) var(--space-lg);
  z-index: 999;
  opacity: 0;
  transform: translateY(-10px);
  transition: opacity var(--duration-normal) var(--ease-default),
              transform var(--duration-normal) var(--ease-default);
}

.mobile-nav.is-open {
  opacity: 1;
  transform: translateY(0);
}

.mobile-nav a {
  display: block;
  padding: var(--space-md) 0;
  font-size: var(--fs-lg);
  font-weight: var(--fw-medium);
  color: var(--color-light-gray);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.mobile-nav a:hover {
  color: var(--color-accent);
}

.mobile-nav .btn {
  margin-top: var(--space-xl);
  width: 100%;
}