/* ============================================================
   Xuzhou Qinglingbo Technology Co., Ltd — Common Stylesheet
   Brand Colors: Industrial Cyan-Ink #0F3B48 / Mech Silver #2C3A47
   Accent: Industrial Cyan #2493AB
   ============================================================ */

/* --- Tailwind CSS CDN --- */
@import url('https://cdn.jsdelivr.net/npm/tailwindcss@2.2.19/dist/tailwind.min.css');

/* --- Google Fonts --- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500&display=swap');

/* ============================================================
   CSS Custom Properties (Design Tokens)
   ============================================================ */
:root {
  /* Primary Brand */
  --color-brand:        #0F3B48;
  --color-brand-light:  #163E4A;
  --color-brand-dark:   #0A2D38;

  /* Secondary */
  --color-mech-silver:  #2C3A47;
  --color-mech-light:   #3D4E5C;

  /* Accent */
  --color-accent:       #2493AB;
  --color-accent-hover: #1C7A8E;
  --color-accent-light: rgba(36,147,171,0.12);

  /* Backgrounds */
  --color-bg-page:      #F8FAFB;
  --color-bg-card:      #FFFFFF;
  --color-overlay:      rgba(15,59,72,0.78);

  /* Text */
  --color-text-heading: #141C23;
  --color-text-body:    #404B56;
  --color-text-muted:   #8392A0;
  --color-text-white:   #FFFFFF;

  /* Borders & Dividers */
  --color-border:       #E2E8F0;
  --color-border-light: #EDF2F7;

  /* Shadows */
  --shadow-card:        0 1px 3px rgba(15,59,72,0.06), 0 6px 16px rgba(15,59,72,0.04);
  --shadow-card-hover:  0 4px 12px rgba(15,59,72,0.08), 0 12px 32px rgba(15,59,72,0.06);
  --shadow-nav:         0 1px 0 rgba(15,59,72,0.06), 0 4px 12px rgba(15,59,72,0.03);

  /* Typography */
  --font-sans:  'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono:  'JetBrains Mono', 'Consolas', monospace;

  /* Spacing */
  --nav-height: 72px;
  --section-gap: 96px;
  --content-max: 1200px;

  /* Transitions */
  --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);
  --duration-fast: 150ms;
  --duration-normal: 300ms;
  --duration-slow: 500ms;
}

/* ============================================================
   Global Reset & Base
   ============================================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text-body);
  background-color: var(--color-bg-page);
  overflow-x: hidden;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-smooth);
}

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

/* ============================================================
   Typography
   ============================================================ */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-text-heading);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2.25rem, 4vw, 3.5rem); }
h2 { font-size: clamp(1.75rem, 3vw, 2.5rem); }
h3 { font-size: clamp(1.25rem, 2vw, 1.5rem); }
h4 { font-size: 1.125rem; }

.section-label {
  display: inline-block;
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 0.75rem;
}

.section-title {
  margin-bottom: 1rem;
}

.section-subtitle {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  max-width: 640px;
  margin: 0 auto 3rem;
  line-height: 1.75;
}

/* ============================================================
   Layout Utilities
   ============================================================ */
.container-wide {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 2rem;
}

.section {
  padding: var(--section-gap) 0;
}

.section-sm {
  padding: 64px 0;
}

.bg-brand {
  background-color: var(--color-brand);
}

.bg-page {
  background-color: var(--color-bg-page);
}

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

/* ============================================================
   Navigation Bar
   ============================================================ */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border-light);
  box-shadow: var(--shadow-nav);
  transition: all var(--duration-normal) var(--ease-smooth);
}

.navbar.scrolled {
  background: rgba(255,255,255,0.97);
  box-shadow: 0 2px 20px rgba(15,59,72,0.08);
}

.navbar-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--color-brand);
  letter-spacing: -0.01em;
  text-decoration: none;
  white-space: nowrap;
}

.nav-logo:hover {
  color: var(--color-brand);
}

.nav-logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--color-brand), var(--color-accent));
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 0.75rem;
  font-weight: 800;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  list-style: none;
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 1rem;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text-body);
  border-radius: 6px;
  transition: all var(--duration-fast) var(--ease-smooth);
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-accent);
  background: var(--color-accent-light);
}

/* Mobile Menu Button */
.mobile-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--color-brand);
}

.mobile-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  margin: 5px 0;
  border-radius: 2px;
  transition: all var(--duration-normal) var(--ease-smooth);
}

.mobile-toggle.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.mobile-toggle.active span:nth-child(2) {
  opacity: 0;
}
.mobile-toggle.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ============================================================
   Hero / Banner
   ============================================================ */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: #fff;
  overflow: hidden;
  background-color: var(--color-brand);
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: url('../images/banners/hero-bg.jpg') center/cover no-repeat;
  z-index: 0;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background: var(--color-overlay);
  z-index: 1;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 800px;
  padding: 0 2rem;
}

.hero-badge {
  display: inline-block;
  padding: 0.375rem 1rem;
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent);
  background: rgba(36,147,171,0.12);
  border: 1px solid rgba(36,147,171,0.25);
  border-radius: 100px;
  margin-bottom: 1.5rem;
}

.hero h1 {
  color: #fff;
  margin-bottom: 1.25rem;
}

.hero p {
  font-size: 1.125rem;
  color: rgba(255,255,255,0.78);
  line-height: 1.8;
  max-width: 640px;
  margin: 0 auto 2rem;
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.75rem;
  font-size: 0.9375rem;
  font-weight: 600;
  font-family: var(--font-sans);
  border-radius: 8px;
  border: none;
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-smooth);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--color-accent);
  color: #fff;
  box-shadow: 0 2px 8px rgba(36,147,171,0.3);
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  color: #fff;
  box-shadow: 0 4px 16px rgba(36,147,171,0.4);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: #fff;
  border: 1.5px solid rgba(255,255,255,0.35);
}

.btn-outline:hover {
  background: rgba(255,255,255,0.08);
  border-color: rgba(255,255,255,0.6);
  color: #fff;
}

.btn-ghost {
  background: transparent;
  color: var(--color-accent);
  border: 1.5px solid transparent;
  padding: 0.625rem 1.25rem;
}

.btn-ghost:hover {
  background: var(--color-accent-light);
  border-color: rgba(36,147,171,0.2);
  color: var(--color-accent-hover);
}

.btn-sm {
  padding: 0.5rem 1.25rem;
  font-size: 0.875rem;
}

.btn-lg {
  padding: 0.875rem 2.25rem;
  font-size: 1rem;
}

/* ============================================================
   Cards
   ============================================================ */
.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 2rem;
  box-shadow: var(--shadow-card);
  transition: all var(--duration-normal) var(--ease-smooth);
}

.card:hover {
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-2px);
  border-color: rgba(36,147,171,0.15);
}

.card-icon {
  width: 52px;
  height: 52px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
  font-size: 1.375rem;
  background: linear-gradient(135deg, rgba(15,59,72,0.06), rgba(36,147,171,0.1));
  color: var(--color-accent);
}

.card h3 {
  font-size: 1.125rem;
  margin-bottom: 0.625rem;
}

.card p {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  line-height: 1.7;
}

/* ============================================================
   Service Card (Large)
   ============================================================ */
.service-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--shadow-card);
  transition: all var(--duration-normal) var(--ease-smooth);
  margin-bottom: 2rem;
}

.service-card:hover {
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-2px);
}

.service-card-img {
  height: 100%;
  min-height: 320px;
  background-size: cover;
  background-position: center;
  position: relative;
}

.service-card-body {
  padding: 2.5rem 2.5rem 2.5rem 0;
}

.service-card-number {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-accent);
  letter-spacing: 0.08em;
  margin-bottom: 0.5rem;
}

.service-card h3 {
  font-size: 1.375rem;
  margin-bottom: 0.75rem;
}

.service-card p {
  color: var(--color-text-muted);
  margin-bottom: 1.5rem;
  line-height: 1.75;
}

.service-card-features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.service-card-features li {
  display: flex;
  align-items: flex-start;
  gap: 0.625rem;
  font-size: 0.9375rem;
  color: var(--color-text-body);
}

.service-card-features li::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
  margin-top: 0.5rem;
  flex-shrink: 0;
}

/* ============================================================
   Stats / Numbers
   ============================================================ */
.stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  text-align: center;
}

.stat-item {
  padding: 1.5rem;
}

.stat-number {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--color-brand);
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-top: 0.375rem;
}

/* ============================================================
   Grid Layouts
   ============================================================ */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

/* ============================================================
   Footer
   ============================================================ */
.footer {
  background: var(--color-brand);
  color: rgba(255,255,255,0.72);
  padding: 4rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 3rem;
}

.footer-brand-name {
  font-size: 1.25rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 0.75rem;
}

.footer-brand-desc {
  font-size: 0.9375rem;
  line-height: 1.7;
  color: rgba(255,255,255,0.6);
}

.footer h4 {
  color: #fff;
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-links a {
  color: rgba(255,255,255,0.6);
  font-size: 0.9375rem;
  transition: color var(--duration-fast) var(--ease-smooth);
}

.footer-links a:hover {
  color: var(--color-accent);
}

.footer-contact-item {
  display: flex;
  align-items: flex-start;
  gap: 0.625rem;
  margin-bottom: 0.75rem;
  font-size: 0.9375rem;
  color: rgba(255,255,255,0.6);
}

.footer-contact-item .icon {
  color: var(--color-accent);
  flex-shrink: 0;
  margin-top: 0.125rem;
}

.footer-divider {
  border: none;
  border-top: 1px solid rgba(255,255,255,0.1);
  margin: 2.5rem 0 0;
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 1.5rem;
  font-size: 0.875rem;
  color: rgba(255,255,255,0.45);
}

/* ============================================================
   Page Header (Inner Pages)
   ============================================================ */
.page-header {
  padding: calc(var(--nav-height) + 4rem) 0 3rem;
  text-align: center;
  background: linear-gradient(180deg, rgba(15,59,72,0.04) 0%, transparent 100%);
  border-bottom: 1px solid var(--color-border-light);
}

.page-header h1 {
  margin-bottom: 0.75rem;
}

.page-header p {
  color: var(--color-text-muted);
  font-size: 1.125rem;
  max-width: 600px;
  margin: 0 auto;
}

/* ============================================================
   Animations (Scroll Reveal)
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease-smooth), transform 0.7s var(--ease-smooth);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

/* ============================================================
   Badge / Tag
   ============================================================ */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.25rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 100px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.badge-accent {
  background: var(--color-accent-light);
  color: var(--color-accent);
}

/* ============================================================
   Contact Info Cards
   ============================================================ */
.contact-card {
  text-align: center;
  padding: 2.5rem 1.5rem;
}

.contact-card .card-icon {
  margin: 0 auto 1rem;
}

.contact-card h3 {
  margin-bottom: 0.5rem;
}

.contact-card p,
.contact-card a {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .service-card { grid-template-columns: 1fr; }
  .service-card-img { min-height: 240px; }
  .service-card-body { padding: 2rem; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .stats-row { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  :root {
    --section-gap: 64px;
  }

  .grid-2,
  .grid-3 { grid-template-columns: 1fr; }

  .mobile-toggle { display: block; }

  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: rgba(255,255,255,0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 1rem;
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 8px 24px rgba(15,59,72,0.08);
    transform: translateY(-110%);
    opacity: 0;
    pointer-events: none;
    transition: all var(--duration-normal) var(--ease-smooth);
  }

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

  .nav-links a {
    width: 100%;
    padding: 0.75rem 1rem;
  }

  .hero h1 { font-size: 1.75rem; }
  .hero p { font-size: 1rem; }

  .footer-grid { grid-template-columns: 1fr; gap: 2rem; }
  .footer-bottom { flex-direction: column; gap: 0.5rem; text-align: center; }
  .stats-row { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .container-wide { padding: 0 1.25rem; }
  .navbar-inner { padding: 0 1.25rem; }
  .stats-row { grid-template-columns: 1fr; }
  .grid-4 { grid-template-columns: 1fr; }
}