/**
 * Purpose: Premium Navigation System Styles
 * Responsibilities: Styling the sticky header, desktop navigation, dropdowns, and off-canvas mobile menu.
 * Dependencies: css/global.css
 * Version: 1.0.0
 */

/* ==========================================================================
   Header Base
   ========================================================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.03);
  z-index: var(--z-sticky);
  transition: height var(--transition-base),
              background-color var(--transition-base),
              box-shadow var(--transition-base),
              border-color var(--transition-base);
  display: flex;
  align-items: center;
}

.header.is-scrolled {
  height: var(--header-height-scrolled);
  background-color: rgba(255, 255, 255, 0.95);
  border-bottom: 1px solid transparent;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}

/* ==========================================================================
   Navigation Container
   ========================================================================== */
.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

/* ==========================================================================
   Brand Logo
   ========================================================================== */
.nav__brand {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  gap: var(--space-3);
  z-index: var(--z-fixed);
  transition: color var(--transition-base), transform var(--transition-fast);
}

.nav__brand-text {
  display: flex;
  flex-direction: column;
  justify-content: center;
  white-space: normal;
  max-width: 140px;
}

.nav__brand-primary {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
  line-height: 1.1;
  transition: color var(--transition-base);
}

.nav__brand-secondary {
  font-family: var(--font-body);
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--color-text-muted);
  margin-top: 1px;
  transition: color var(--transition-base);
}

@media (min-width: 375px) {
  .nav__brand-text {
    max-width: 160px;
  }
  .nav__brand-primary {
    font-size: 1.125rem;
  }
  .nav__brand-secondary {
    font-size: 0.7rem;
  }
}

@media (min-width: 1024px) {
  .nav__brand-text {
    max-width: 200px;
  }
  .nav__brand-primary {
    font-size: 1.25rem;
  }
  .nav__brand-secondary {
    font-size: 0.75rem;
  }
}

.nav__brand:hover .nav__brand-primary {
  color: var(--color-accent);
}

.nav__brand:hover .nav__brand-secondary {
  color: var(--color-text-secondary);
}

.nav__brand:hover {
  transform: translateY(-1px);
}

/* ==========================================================================
   Desktop Navigation List
   ========================================================================== */
.nav__list {
  display: none;
  align-items: center;
  gap: var(--space-8);
}

@media (min-width: 1024px) {
  .nav__list {
    display: flex;
  }
}

.nav__item {
  position: relative;
}

.nav__link {
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--color-text-secondary);
  padding-block: var(--space-2);
  transition: color var(--transition-base);
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav__link:hover,
.nav__link[aria-current="page"] {
  color: var(--color-text-primary);
}

/* Underline Animation */
.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--color-accent);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  border-radius: 2px;
}

.nav__link:hover::after,
.nav__link[aria-current="page"]::after {
  transform: scaleX(1);
  transform-origin: left;
}

/* Chevron Icon */
.nav__chevron {
  width: 16px;
  height: 16px;
  transition: transform var(--transition-base);
}

.nav__link[aria-expanded="true"] .nav__chevron {
  transform: rotate(180deg);
}

/* ==========================================================================
   Dropdown Menu
   ========================================================================== */
.nav__dropdown {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(10px);
  background-color: var(--color-surface);
  min-width: 260px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-dropdown);
  padding: var(--space-2) 0;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-base),
              transform var(--transition-base),
              visibility var(--transition-base);
  z-index: var(--z-dropdown);
  pointer-events: none;
  border: 1px solid var(--color-border);
}

.nav__item:hover .nav__dropdown,
.nav__link[aria-expanded="true"] + .nav__dropdown,
.nav__dropdown:focus-within {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
  pointer-events: auto;
}

.nav__dropdown-item {
  display: block;
}

.nav__dropdown-link {
  display: block;
  padding: var(--space-2) var(--space-4);
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
  transition: background-color var(--transition-fast),
              color var(--transition-fast);
}

.nav__dropdown-link:hover,
.nav__dropdown-link:focus-visible {
  background-color: var(--color-surface-hover);
  color: var(--color-accent);
  outline: none;
}

/* ==========================================================================
   Navigation Actions (Right side)
   ========================================================================== */
.nav__actions {
  display: none;
  align-items: center;
  gap: var(--space-4);
}

@media (min-width: 1024px) {
  .nav__actions {
    display: flex;
  }
}


/* Primary Button */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-primary);
  color: var(--color-surface);
  font-size: var(--text-sm);
  font-weight: 500;
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-full);
  transition: background-color var(--transition-base),
              transform var(--transition-fast),
              box-shadow var(--transition-base);
  text-align: center;
}

.btn-primary:hover {
  background-color: var(--color-text-primary);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-primary:active {
  transform: translateY(0);
}

/* Secondary/Call Button */
.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-primary);
  font-size: var(--text-sm);
  font-weight: 600;
  gap: var(--space-2);
  transition: color var(--transition-fast);
}

.btn-secondary:hover {
  color: var(--color-accent);
}

.btn-secondary svg {
  width: 18px;
  height: 18px;
}

/* ==========================================================================
   Mobile Navigation Toggle
   ========================================================================== */
.nav__toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 44px;
  height: 44px;
  z-index: var(--z-fixed);
  position: relative;
}

@media (min-width: 1024px) {
  .nav__toggle {
    display: none;
  }
}

.nav__toggle-line {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text-primary);
  transition: transform var(--transition-base),
              opacity var(--transition-base);
  position: absolute;
}

.nav__toggle-line:nth-child(1) { transform: translateY(-6px); }
.nav__toggle-line:nth-child(2) { transform: translateY(0); }
.nav__toggle-line:nth-child(3) { transform: translateY(6px); }

.nav__toggle[aria-expanded="true"] .nav__toggle-line:nth-child(1) {
  transform: translateY(0) rotate(45deg);
}

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

.nav__toggle[aria-expanded="true"] .nav__toggle-line:nth-child(3) {
  transform: translateY(0) rotate(-45deg);
}

/* ==========================================================================
   Mobile Off-Canvas Menu
   ========================================================================== */
.nav__mobile-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(17, 24, 39, 0.4);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: var(--z-overlay);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-base),
              visibility var(--transition-base);
}

.nav__mobile-overlay.is-active {
  opacity: 1;
  visibility: visible;
}

@media (min-width: 1024px) {
  .nav__mobile-overlay {
    display: none;
  }
}

.nav__mobile-menu {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  max-width: 400px;
  background-color: var(--color-surface);
  z-index: var(--z-modal);
  transform: translateX(100%);
  transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
  display: flex;
  flex-direction: column;
  /* FIX: Replaced var(--header-height) top padding with compact spacing
     to eliminate the white space gap when the menu opens */
  padding: var(--space-6) clamp(var(--space-6), 5vw, var(--space-12)) var(--space-8);
  overflow-y: auto;
}

.nav__mobile-menu.is-active {
  transform: translateX(0);
}

@media (min-width: 1024px) {
  .nav__mobile-menu {
    display: none;
  }
}

.nav__mobile-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-4);
  border-bottom: 1px solid var(--color-border);
}

.nav__mobile-close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  color: var(--color-text-primary);
  border-radius: var(--radius-full);
  background-color: var(--color-surface-hover);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.nav__mobile-close:hover {
  background-color: var(--color-border);
  color: var(--color-accent);
}

.nav__mobile-close svg {
  width: 24px;
  height: 24px;
}

.nav__mobile-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin-bottom: var(--space-8);
  margin-top: var(--space-2);
}

.nav__mobile-list > li {
  opacity: 0;
  transform: translateX(20px);
  transition: opacity 0.4s cubic-bezier(0.16, 1, 0.3, 1), 
              transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.nav__mobile-menu.is-active .nav__mobile-list > li {
  opacity: 1;
  transform: translateX(0);
}

/* Staggered transition delays */
.nav__mobile-menu.is-active .nav__mobile-list > li:nth-child(1) { transition-delay: 0.1s; }
.nav__mobile-menu.is-active .nav__mobile-list > li:nth-child(2) { transition-delay: 0.15s; }
.nav__mobile-menu.is-active .nav__mobile-list > li:nth-child(3) { transition-delay: 0.2s; }
.nav__mobile-menu.is-active .nav__mobile-list > li:nth-child(4) { transition-delay: 0.25s; }
.nav__mobile-menu.is-active .nav__mobile-list > li:nth-child(5) { transition-delay: 0.3s; }
.nav__mobile-menu.is-active .nav__mobile-list > li:nth-child(6) { transition-delay: 0.35s; }
.nav__mobile-menu.is-active .nav__mobile-list > li:nth-child(7) { transition-delay: 0.4s; }

.nav__mobile-link {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--color-text-primary);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-block: var(--space-4);
  border-bottom: 1px solid var(--color-divider);
  transition: color var(--transition-base),
              transform var(--transition-base),
              background-color var(--transition-fast);
}

.nav__mobile-link:hover,
.nav__mobile-link[aria-current="page"] {
  color: var(--color-accent);
}

.nav__mobile-link[aria-current="page"] {
  position: relative;
}

.nav__mobile-link[aria-current="page"]::before {
  content: '';
  position: absolute;
  left: -clamp(var(--space-6), 5vw, var(--space-12));
  top: 0;
  bottom: 0;
  width: 3px;
  background-color: var(--color-accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.nav__mobile-link:hover {
  transform: translateX(4px);
}

/* Mobile Dropdown */
.nav__mobile-dropdown {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows var(--transition-base);
}

.nav__mobile-dropdown.is-open {
  grid-template-rows: 1fr;
}

.nav__mobile-dropdown-inner {
  overflow: hidden;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding-left: var(--space-4);
  padding-top: var(--space-2);
}

.nav__mobile-dropdown-link {
  font-size: var(--text-base);
  color: var(--color-text-secondary);
  padding-block: var(--space-2);
  display: block;
}

.nav__mobile-dropdown-link:hover {
  color: var(--color-accent);
}

/* Mobile Actions */
.nav__mobile-actions {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-3);
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-border);
}

.nav__mobile-actions .btn-primary,
.nav__mobile-actions .btn-secondary {
  width: min(100%, 260px);
  min-height: 48px;
  justify-content: center;
  align-items: center;
  text-align: center;
  margin-inline: auto;
}

.nav__mobile-actions .btn-primary {
  padding: var(--space-4) var(--space-6);
  font-size: var(--text-base);
  font-weight: 600;
}

.nav__mobile-actions .btn-secondary {
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-base);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface-hover);
  transition: background-color var(--transition-fast),
              color var(--transition-fast);
}

@media (max-width: 480px) {
  .nav__mobile-menu {
    padding: var(--space-4) var(--space-4) var(--space-6);
  }

  .nav__mobile-link {
    font-size: var(--text-base);
    padding-block: var(--space-3);
  }

  .nav__mobile-actions {
    gap: var(--space-2);
  }
}

.nav__mobile-actions .btn-secondary:hover {
  background-color: var(--color-border);
  color: var(--color-accent);
}