/* ==========================================================================
   NAVIGATION BAR
   Fixed top navigation, theme toggle, and mobile menu overlay.
   ========================================================================== */

/* -- Desktop Nav --------------------------------------------------------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--nav-height);
  z-index: var(--z-sticky);
  transition: background-color var(--duration-slow) var(--ease-out), 
              border-color var(--duration-slow) var(--ease-out),
              box-shadow var(--duration-slow) var(--ease-out),
              padding var(--duration) var(--ease-out);
  display: flex;
  align-items: center;
  background: transparent;
}

/* Scrolled state — glass morphism */
.nav.scrolled {
  background: var(--c-nav-bg);
  backdrop-filter: blur(16px) saturate(1.4);
  -webkit-backdrop-filter: blur(16px) saturate(1.4);
  border-bottom: 1px solid var(--c-border);
  box-shadow: var(--shadow-sm);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

/* -- Logo ---------------------------------------------------------------- */
.logo {
  text-decoration: none;
  display: flex;
  align-items: center;
  z-index: calc(var(--z-modal) + 2);
  flex-shrink: 0;
}

.logo-img {
  height: 40px;
  width: auto;
  display: block;
  mix-blend-mode: multiply;
  transition: opacity var(--duration) ease;
}

.logo-img--dark { display: none; }

[data-theme="dark"] .logo-img--light { display: none; }
[data-theme="dark"] .logo-img--dark  {
  display: block;
  mix-blend-mode: normal;
  filter: brightness(0) invert(1);
}

/* Fallback text logo (if image fails) */
.logo-text {
  font-family: var(--ff-heading);
  font-weight: var(--fw-bold);
  font-size: 1.25rem;
  color: var(--c-text);
  letter-spacing: var(--ls-tight);
  display: none;
}

.logo span { color: var(--c-primary); }

/* -- Desktop Links ------------------------------------------------------- */
.nav-links {
  display: none;
}

@media (min-width: 768px) {
  .nav-links {
    display: flex;
    gap: var(--sp-lg);
    align-items: center;
  }
}

.nav-links a {
  font-family: var(--ff-body);
  font-size: var(--fs-body-sm);
  font-weight: var(--fw-medium);
  color: var(--c-text-2);
  text-decoration: none;
  padding: var(--sp-xs) 0;
  position: relative;
  transition: color var(--duration-fast) var(--ease-out);
}

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

/* Active/Hover line */
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--c-primary);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform var(--duration) var(--ease-out);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  transform: scaleX(1);
  transform-origin: left;
}

/* -- CTA & Actions Container --------------------------------------------- */
.nav-cta {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  z-index: calc(var(--z-modal) + 2);
}

@media (min-width: 768px) {
  .nav-cta {
    gap: var(--sp-md);
  }
}

@media (max-width: 767px) {
  .nav-cta .btn {
    display: none; /* Hide primary CTA button on mobile */
  }
}

/* -- Theme Toggle Button ------------------------------------------------- */
.theme-toggle {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--c-text-2);
  background: transparent;
  transition: all var(--duration-fast) var(--ease-out);
  position: relative;
  overflow: hidden;
}

.theme-toggle:hover {
  background: var(--c-surface-raised);
  color: var(--c-primary);
  transform: scale(1.05);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  position: absolute;
  transition: transform 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55), 
              opacity 0.3s var(--ease-out);
}

/* Sun Icon (shown in dark mode, ready to switch to light) */
.theme-toggle .sun-icon {
  opacity: 0;
  transform: rotate(90deg) scale(0.5);
}

/* Moon Icon (shown in light mode, ready to switch to dark) */
.theme-toggle .moon-icon {
  opacity: 1;
  transform: rotate(0) scale(1);
}

/* Dark theme active states */
:root[data-theme="dark"] .theme-toggle .sun-icon {
  opacity: 1;
  transform: rotate(0) scale(1);
}

:root[data-theme="dark"] .theme-toggle .moon-icon {
  opacity: 0;
  transform: rotate(-90deg) scale(0.5);
}

/* -- Mobile Burger ------------------------------------------------------- */
.burger {
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  width: 28px;
  height: 24px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0;
  margin-left: var(--sp-xs);
  z-index: calc(var(--z-modal) + 2);
}

.burger span {
  width: 100%;
  height: 2px;
  background: var(--c-text);
  border-radius: var(--radius-pill);
  transition: all 0.3s cubic-bezier(0.645, 0.045, 0.355, 1);
  transform-origin: 1px;
}

/* Burger animation to X */
.menu-open .burger span:nth-child(1) {
  transform: rotate(45deg) translate(2px, -2px);
}
.menu-open .burger span:nth-child(2) {
  opacity: 0;
  transform: translateX(-10px);
}
.menu-open .burger span:nth-child(3) {
  transform: rotate(-45deg) translate(2px, 2px);
}

@media (min-width: 768px) {
  .burger {
    display: none;
  }
}

/* -- Mobile Menu Overlay ------------------------------------------------- */
.mobile-menu {
  position: fixed;
  inset: 0;
  background: var(--c-surface-overlay);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  z-index: var(--z-modal);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transform: translateY(-100%);
  transition: transform 0.4s var(--ease-in-out), background-color var(--duration-slow) var(--ease-out);
  visibility: hidden;
}

.menu-open .mobile-menu {
  transform: translateY(0);
  visibility: visible;
}

.mm-links {
  display: flex;
  flex-direction: column;
  gap: var(--sp-xl);
  text-align: center;
  margin-bottom: var(--sp-2xl);
  width: 100%;
}

.mm-links a {
  font-family: var(--ff-heading);
  font-size: var(--fs-h3);
  font-weight: var(--fw-semibold);
  color: var(--c-text);
  text-decoration: none;
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.3s var(--ease-out);
}

.mm-links a:hover {
  color: var(--c-primary);
}

/* Staggered link animation on open */
.menu-open .mm-links a {
  opacity: 1;
  transform: translateY(0);
}
.menu-open .mm-links a:nth-child(1) { transition-delay: 100ms; }
.menu-open .mm-links a:nth-child(2) { transition-delay: 150ms; }
.menu-open .mm-links a:nth-child(3) { transition-delay: 200ms; }
.menu-open .mm-links a:nth-child(4) { transition-delay: 250ms; }
.menu-open .mm-links a:nth-child(5) { transition-delay: 300ms; }
.menu-open .mm-links a:nth-child(6) { transition-delay: 350ms; }

.mm-cta {
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.3s var(--ease-out);
  transition-delay: 400ms;
}

.menu-open .mm-cta {
  opacity: 1;
  transform: translateY(0);
}

/* Prevent body scroll when menu is open */
body.menu-open {
  overflow: hidden;
}

/* Footer logo — same light/dark behaviour, smaller height */
.footer-logo { height: 36px; }