/* ── Header ─────────────────────────────── */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 22px 0;
  border-bottom: 1px solid transparent;
  transition: background var(--transition), padding var(--transition),
              border-color var(--transition), backdrop-filter var(--transition);
}

.site-header.scrolled {
  background: rgba(10, 10, 15, 0.88);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: 14px 0;
  border-bottom-color: var(--color-border);
}

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

/* ── Logo ── */
.header-logo {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 1.3rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  word-spacing: 0;
  color: var(--color-text);
  transition: opacity var(--transition);
}

.header-logo-img {
  height: 28px;
  width: auto;
}

.header-logo span { color: var(--color-accent); }
.header-logo:hover { opacity: 0.75; }

/* ── Desktop Nav ── */
.header-nav {
  display: flex;
  align-items: center;
  gap: 36px;
}

.nav-link {
  position: relative;
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--color-muted);
  transition: color var(--transition);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1.5px;
  background: var(--color-accent);
  border-radius: 2px;
  transition: width 0.25s ease;
}

.nav-link:hover { color: var(--color-text); }
.nav-link:hover::after { width: 100%; }

.header-nav .btn-primary {
  font-size: 0.85rem;
  padding: 10px 22px;
  margin-left: 4px;
  color: #fff;
  transition: transform 0.25s ease, box-shadow 0.25s ease, filter 0.25s ease;
}

.header-nav .btn-primary:hover {
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 10px 32px rgba(59, 130, 246, 0.5), inset 0 1px 0 rgba(255, 255, 255, 0.2);
  filter: brightness(1.1);
}

.header-nav .btn-primary:active {
  transform: translateY(0);
  box-shadow: 0 2px 10px rgba(59, 130, 246, 0.3);
}

/* No underline animation on the CTA button */
.header-nav .btn-primary::after { display: none; }

/* ── Hamburger ── */
.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--color-border);
  color: var(--color-text);
  font-size: 1rem;
  transition: background var(--transition), border-color var(--transition), color var(--transition);
}

.nav-toggle:hover {
  background: rgba(255, 255, 255, 0.09);
  border-color: rgba(255, 255, 255, 0.15);
}

.nav-toggle.open {
  background: rgba(59, 130, 246, 0.12);
  border-color: rgba(59, 130, 246, 0.35);
  color: var(--color-accent);
}

.nav-icon-close { display: none; }
.nav-toggle.open .nav-icon-bars  { display: none; }
.nav-toggle.open .nav-icon-close { display: block; }

/* ── Responsive ─────────────────────────── */
@media (max-width: 820px) {

  /* Always-active background on mobile */
  .site-header {
    background: rgba(10, 10, 15, 0.92);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom-color: var(--color-border);
    padding: 14px 0;
  }

  .nav-toggle { display: flex; }

  .header-nav {
    position: absolute;
    top: calc(100% + 1px);
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: rgba(10, 10, 15, 0.97);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
    padding: 8px 0 20px;
    /* Slide-down + fade animation */
    visibility: hidden;
    opacity: 0;
    transform: translateY(-10px);
    pointer-events: none;
    transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s;
  }

  .header-nav.open {
    visibility: visible;
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
  }

  .nav-link {
    width: 100%;
    padding: 14px 24px;
    font-size: 0.95rem;
    color: var(--color-muted);
    border-bottom: 1px solid rgba(255, 255, 255, 0.04);
    transition: background var(--transition), color var(--transition), padding-left 0.2s ease;
  }

  .nav-link::after { display: none; }

  .nav-link:hover {
    background: rgba(59, 130, 246, 0.06);
    color: var(--color-text);
    padding-left: 30px;
  }

  .header-nav .btn-primary {
    margin: 16px 24px 0;
    width: calc(100% - 48px);
    justify-content: center;
    padding: 13px 22px;
  }
}