/* ==========================================================================
   BONGSHAI ENGINEERING & CONSTRUCTION - MAIN STYLESHEET (UPGRADED)
   Ultrafast, Accessible, Responsive CSS Design System + Mega Menu Engine
   ========================================================================== */

:root {
  /* Brand Palette - Clean Light Engineering Theme */
  --color-primary: #0f172a;       /* Deep Slate Blue */
  --color-primary-light: #1e293b; /* Slate Card Surface */
  --color-accent: #eab308;        /* Construction Gold Yellow */
  --color-accent-hover: #ca8a04;  /* Deep Gold */
  --color-accent-soft: rgba(234, 179, 8, 0.12);
  
  --color-text-main: #0f172a;
  --color-text-muted: #475569;
  --color-text-light: #f8fafc;
  
  --color-bg-body: #f8fafc;
  --color-bg-card: #ffffff;
  --color-bg-card-alt: #f1f5f9;
  --color-border: #e2e8f0;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.12), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  --glass-bg: rgba(255, 255, 255, 0.95);
  --glass-border: rgba(226, 232, 240, 0.8);
  --glass-backdrop: blur(16px);
  
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;
  --font-heading: 'Outfit', system-ui, -apple-system, sans-serif;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  
  --container-max: 1280px;
  --header-height: 80px;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg-body);
  color: var(--color-text-main);
  line-height: 1.6;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

ul {
  list-style: none;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.25rem;
  padding-right: 1.25rem;
}

.section {
  padding: 5rem 0;
  position: relative;
}

.section-alt {
  background-color: var(--color-bg-card-alt);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  padding: 0.85rem 1.75rem;
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 0.95rem;
  transition: all var(--transition-fast);
  white-space: nowrap;
  cursor: pointer;
}

.btn-primary {
  background-color: var(--color-accent);
  color: #0f172a;
  box-shadow: 0 4px 14px rgba(234, 179, 8, 0.35);
}

.btn-primary:hover {
  background-color: var(--color-accent-hover);
  transform: translateY(-2px);
}

.btn-outline {
  border: 2px solid var(--color-accent);
  color: var(--color-accent);
  background: transparent;
}

.btn-outline:hover {
  background-color: var(--color-accent);
  color: #0f172a;
}

/* --------------------------------------------------------------------------
   Header & Upgraded Mega Menu Navigation
   -------------------------------------------------------------------------- */
.top-bar {
  background-color: var(--color-primary);
  color: #94a3b8;
  font-size: 0.85rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

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

.top-contacts {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.top-contact-item {
  color: #e2e8f0;
}

.top-contact-item:hover {
  color: var(--color-accent);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--glass-bg);
  backdrop-filter: var(--glass-backdrop);
  border-bottom: 1px solid var(--glass-border);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-weight: 800;
  font-size: 1.35rem;
  color: var(--color-text-main);
  text-transform: uppercase;
}

.brand-badge-logo {
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
  border: 2px solid var(--color-accent);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-accent);
  font-weight: 900;
}

.brand-text-sub {
  display: block;
  font-size: 0.7rem;
  color: var(--color-accent-hover);
  letter-spacing: 0.15em;
  font-weight: 700;
}

.main-nav {
  display: flex;
  align-items: center;
}

.main-nav > ul {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  flex-wrap: nowrap;
}

.nav-item {
  position: relative;
  white-space: nowrap;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.6rem 0.8rem;
  font-weight: 600;
  font-size: 0.92rem;
  color: var(--color-text-main);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.nav-link:hover, .nav-item:hover > .nav-link, .nav-link.active {
  color: var(--color-accent-hover);
  background-color: var(--color-accent-soft);
}

.nav-link svg.chevron {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  transition: transform var(--transition-fast);
}

.nav-item:hover > .nav-link svg.chevron {
  transform: rotate(180deg);
}

/* Upgraded Mega Menu & Standard Dropdown Container */
.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 270px;
  width: max-content;
  max-width: 380px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xl);
  padding: 0.5rem 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all 0.2s ease-in-out;
  z-index: 1200;
}

.nav-item:hover > .dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.dropdown-item {
  position: relative;
  white-space: nowrap;
}

.dropdown-link {
  display: block;
  padding: 0.65rem 1.25rem;
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--color-text-main);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.dropdown-link:hover {
  background: var(--color-bg-card-alt);
  color: var(--color-accent-hover);
  padding-left: 1.5rem;
}

.mega-menu {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(15px);
  width: max-content;
  min-width: 650px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  padding: 1.75rem;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 1200;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.nav-item:hover > .mega-menu {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.mega-menu-single {
  min-width: 320px;
  grid-template-columns: 1fr;
}

.mega-menu-header {
  font-size: 0.8rem;
  font-weight: 800;
  color: var(--color-accent-hover);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.75rem;
  padding-bottom: 0.4rem;
  border-bottom: 2px solid var(--color-accent-soft);
}

.mega-menu-item {
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
  padding: 0.65rem 0.85rem;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.mega-menu-item:hover {
  background: var(--color-bg-card-alt);
  transform: translateX(4px);
}

.mega-icon {
  width: 36px;
  height: 36px;
  background: var(--color-accent-soft);
  color: var(--color-accent-hover);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  flex-shrink: 0;
}

.mega-title {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--color-text-main);
  line-height: 1.3;
}

.mega-desc {
  font-size: 0.78rem;
  color: var(--color-text-muted);
  line-height: 1.4;
  margin-top: 0.15rem;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.theme-toggle-btn {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg-card-alt);
  color: var(--color-text-main);
  border: 1px solid var(--color-border);
  cursor: pointer;
}

/* Off-canvas Mobile Menu Drawer */
.mobile-nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border-radius: var(--radius-sm);
  background: var(--color-bg-card-alt);
  color: var(--color-text-main);
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   Mobile Drawer & Accordion Navigation (Upgraded)
   -------------------------------------------------------------------------- */
.mobile-drawer {
  position: fixed;
  inset: 0;
  background: var(--color-bg-card);
  z-index: 2500;
  display: flex;
  flex-direction: column;
  padding: 1.5rem;
  overflow-y: auto;
  transform: translateX(100%);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.mobile-drawer.active {
  transform: translateX(0);
}

.mobile-drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 1.5rem;
}

.mobile-drawer-close {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-full);
  background: var(--color-bg-card-alt);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  cursor: pointer;
  border: none;
  color: var(--color-text-main);
}

.mobile-menu-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.mobile-menu-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1rem;
  background: var(--color-bg-card-alt);
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 1rem;
  color: var(--color-text-main);
}

.mobile-submenu {
  display: none;
  flex-direction: column;
  gap: 0.5rem;
  padding: 0.5rem 0 0.5rem 1rem;
}

.mobile-submenu.active {
  display: flex;
}

.mobile-sub-link {
  display: block;
  padding: 0.55rem 0.75rem;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  border-left: 2px solid var(--color-accent);
}

/* Responsive Media Queries */
@media (max-width: 1180px) {
  .main-nav {
    display: none;
  }
  .mobile-nav-toggle {
    display: flex;
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  .top-bar {
    display: none;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .section-title {
    font-size: 1.65rem;
  }
  .section {
    padding: 3.5rem 0;
  }
  .project-grid {
    grid-template-columns: 1fr;
  }
}

/* --------------------------------------------------------------------------
   Visual Aesthetics & Premium UI Utilities
   -------------------------------------------------------------------------- */
.glass-card {
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(226, 232, 240, 0.8);
  box-shadow: 0 10px 30px -5px rgba(15, 23, 42, 0.08);
  border-radius: var(--radius-lg);
  transition: all var(--transition-normal);
}

.glass-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 40px -10px rgba(15, 23, 42, 0.12);
  border-color: var(--color-accent);
}

.section-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1.1rem;
  background: var(--color-accent-soft);
  color: var(--color-accent-hover);
  border: 1px solid rgba(234, 179, 8, 0.3);
  border-radius: var(--radius-full);
  font-size: 0.825rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 1rem;
  position: relative;
  overflow: hidden;
}

.section-badge::after {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.6), transparent);
  animation: shimmer 3s infinite;
}

@keyframes shimmer {
  100% {
    left: 100%;
  }
}

@keyframes floatElement {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-6px);
  }
}

@keyframes pulseGlow {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(234, 179, 8, 0.4);
  }
  50% {
    box-shadow: 0 0 0 12px rgba(234, 179, 8, 0);
  }
}

.btn-primary {
  position: relative;
  overflow: hidden;
  z-index: 1;
}

.btn-primary::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.35), transparent);
  transition: left 0.6s ease;
  z-index: -1;
}

.btn-primary:hover::before {
  left: 100%;
}


/* --------------------------------------------------------------------------
   Entry Animations
   -------------------------------------------------------------------------- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.animate-fade-in-up {
  animation: fadeInUp 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.animate-delay-1 {
  animation-delay: 0.1s;
}

.animate-delay-2 {
  animation-delay: 0.2s;
}

.animate-delay-3 {
  animation-delay: 0.3s;
}

/* Enhancing hover state for all generic cards */
div[style*="background: var(--color-bg-card)"] {
  transition: all var(--transition-normal);
}

div[style*="background: var(--color-bg-card)"]:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-xl) !important;
  border-color: var(--color-accent) !important;
}