/* ========================================
   UAV Enterprise Survey Website
   Main Style Sheet
   ======================================== */

/* ----------------------------------------
   CSS Variables (Design Tokens)
   ---------------------------------------- */
:root {
  /* Colors */
  --color-primary: #0056b3;
  --color-primary-dark: #004494;
  --color-primary-light: #0066cc;
  --color-secondary: #333333;
  --color-secondary-light: #555555;
  --color-accent: #d93025;
  --color-accent-dark: #b5281f;
  --color-accent-light: #e63936;

  /* Neutral Colors */
  --color-white: #ffffff;
  --color-bg-light: #f5f7fa;
  --color-bg-gray: #e8ecf0;
  --color-text-primary: #222222;
  --color-text-secondary: #666666;
  --color-text-light: #999999;
  --color-border: #dde2e8;
  --color-border-dark: #c5cacd;

  /* Typography */
  --font-family-primary: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Helvetica, Arial, sans-serif;
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-base: 16px;
  --font-size-md: 18px;
  --font-size-lg: 20px;
  --font-size-xl: 24px;
  --font-size-2xl: 30px;
  --font-size-3xl: 36px;
  --font-size-4xl: 48px;

  /* Spacing */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  --spacing-3xl: 64px;
  --spacing-4xl: 96px;

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 50%;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.15);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;

  /* Z-index */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-modal: 300;
  --z-tooltip: 400;

  /* Container */
  --container-max: 1200px;
  --container-padding: 20px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family-primary);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text-primary);
  background-color: var(--color-white);
  min-height: 100vh;
}

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

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

a:hover {
  color: var(--color-primary-dark);
}

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
}

h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }
h5 { font-size: var(--font-size-lg); }
h6 { font-size: var(--font-size-md); }

/* ----------------------------------------
   Layout Utilities
   ---------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.section {
  padding: var(--spacing-3xl) 0;
}

.section-sm {
  padding: var(--spacing-2xl) 0;
}

.section-lg {
  padding: var(--spacing-4xl) 0;
}

.row {
  display: flex;
  flex-wrap: wrap;
  margin: 0 calc(var(--spacing-md) * -1);
}

.col {
  flex: 1;
  padding: 0 var(--spacing-md);
}

.grid {
  display: grid;
  gap: var(--spacing-lg);
}

/* ----------------------------------------
   Header & Navigation
   ---------------------------------------- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-sticky);
  background-color: var(--color-white);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition-normal);
}

.header.scrolled {
  box-shadow: var(--shadow-md);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 104px;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 20px;
}

.logo {
  display: flex;
  align-items: center;
  text-decoration: none;
  flex: 0 0 auto;
}

.logo-icon {
  width: 320px;
  height: 80px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background-image: url('../images/logo.jpg');
  background-repeat: no-repeat;
  background-position: left center;
  background-size: contain;
}

.logo-icon svg,
.logo-icon img {
  display: none !important;
}

.logo-icon img {
  border-radius: 0;
}

.logo-text {
  display: none !important;
  flex-direction: column;
}

.logo-name {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.2;
}

.logo-sub {
  font-size: var(--font-size-xs);
  color: var(--color-text-secondary);
  font-weight: 400;
}

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

.nav-list {
  display: flex;
  align-items: center;
  gap: 12px;
  list-style: none;
  margin: 0;
  padding: 0;
  overflow: visible;
}

.nav-item {
  position: relative;
}

.nav-link {
  display: inline-grid;
  grid-template-columns: auto auto;
  grid-template-rows: auto auto;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: 60px;
  padding: 10px 12px;
  color: var(--color-text-primary);
  font-size: 19px;
  font-weight: 700;
  line-height: 1.08;
  border-radius: var(--radius-md);
  transition: color var(--transition-fast), background-color var(--transition-fast), box-shadow var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-primary);
  background-color: rgba(0, 86, 179, 0.08);
  box-shadow: inset 0 -2px 0 rgba(0, 86, 179, 0.12);
}

.nav-link::after {
  content: attr(data-nav-code);
  grid-column: 1 / -1;
  display: block;
  margin-top: 4px;
  font-size: 12px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.12em;
  color: var(--color-text-light);
  text-align: center;
  text-transform: uppercase;
  transition: color var(--transition-fast);
}

.nav-link:hover::after,
.nav-link.active::after {
  color: var(--color-primary);
}

/* Dropdown Menu */
.dropdown-toggle {
  cursor: pointer;
}

.dropdown-toggle svg {
  grid-row: 1;
  grid-column: 2;
  width: 15px;
  height: 15px;
  transition: transform var(--transition-fast);
}

.nav-item.dropdown:hover .dropdown-toggle svg {
  transform: rotate(180deg);
}

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  min-width: 200px;
  background-color: var(--color-white);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-fast), visibility var(--transition-fast);
  padding: var(--spacing-sm) 0;
  margin-top: var(--spacing-sm);
  z-index: 1000;
}

.nav-item.dropdown:hover .dropdown-menu {
  opacity: 1;
  visibility: visible;
}

.dropdown-menu a {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  transition: background-color var(--transition-fast), color var(--transition-fast);
  white-space: nowrap;
}

.dropdown-menu a:hover {
  background-color: var(--color-bg-light);
  color: var(--color-primary);
}

/* Header Actions */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.header-actions .btn {
  height: 48px;
  padding: 0 22px;
  font-size: 16px;
  font-weight: 600;
}

.header-actions .btn-accent {
  background-color: var(--color-accent);
  color: var(--color-white);
  border: none;
}

.header-actions .btn-accent:hover {
  background-color: var(--color-accent-dark);
}

/* Mobile Menu Toggle */
.menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 30px;
  height: 30px;
  cursor: pointer;
}

@media (max-width: 991px) {
  .nav {
    display: none;
  }

  .header-actions {
    display: none;
  }

  .menu-toggle {
    display: flex;
  }
}

.menu-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--color-text-primary);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.menu-toggle.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ----------------------------------------
   Hero Section
   ---------------------------------------- */
.hero {
  position: relative;
  min-height: 600px;
  display: flex;
  align-items: center;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: var(--color-white);
  margin-top: 70px;
}

.hero-bg {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-size: cover;
  background-position: center;
  opacity: 0.1;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(90deg, rgba(0, 86, 179, 0.9) 0%, rgba(0, 68, 148, 0.7) 100%);
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 700px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-xs) var(--spacing-md);
  background-color: rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-full);
  font-size: var(--font-size-sm);
  margin-bottom: var(--spacing-lg);
}

.hero-title {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  margin-bottom: var(--spacing-lg);
  line-height: 1.2;
}

.hero-subtitle {
  font-size: var(--font-size-lg);
  opacity: 0.9;
  margin-bottom: var(--spacing-xl);
  line-height: 1.6;
}

.hero-actions {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

/* ----------------------------------------
   Footer
   ---------------------------------------- */
.footer {
  background-color: var(--color-secondary);
  color: var(--color-white);
  padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
}

.footer-brand {
  max-width: 300px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}

.footer-logo svg {
  width: 40px;
  height: 40px;
}

.footer-logo-text {
  font-size: var(--font-size-lg);
  font-weight: 700;
}

.footer-desc {
  font-size: var(--font-size-sm);
  opacity: 0.8;
  line-height: 1.6;
  margin-bottom: var(--spacing-md);
}

.footer-social {
  display: flex;
  gap: var(--spacing-md);
}

.footer-social a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background-color: rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-full);
  color: var(--color-white);
  transition: background-color var(--transition-fast);
}

.footer-social a:hover {
  background-color: var(--color-primary);
}

.footer-title {
  font-size: var(--font-size-md);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.footer-links a {
  color: rgba(255, 255, 255, 0.8);
  font-size: var(--font-size-sm);
  transition: color var(--transition-fast);
}

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

.footer-contact-item {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
  font-size: var(--font-size-sm);
  color: rgba(255, 255, 255, 0.8);
}

.footer-contact-item svg {
  flex-shrink: 0;
  width: 18px;
  height: 18px;
  margin-top: 2px;
}

.footer-bottom {
  padding-top: var(--spacing-lg);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.footer-copyright {
  font-size: var(--font-size-sm);
  opacity: 0.7;
}

.footer-legal {
  display: flex;
  gap: var(--spacing-lg);
}

.footer-legal a {
  font-size: var(--font-size-sm);
  color: rgba(255, 255, 255, 0.7);
}

.footer-legal a:hover {
  color: var(--color-white);
}

/* ----------------------------------------
   Page Header (Breadcrumb)
   ---------------------------------------- */
.page-header {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: var(--color-white);
  padding: var(--spacing-3xl) 0;
  margin-top: 104px;
}

.page-title {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: var(--font-size-sm);
  opacity: 0.9;
}

.breadcrumb-item {
  display: flex;
  align-items: center;
}

.breadcrumb-item + .breadcrumb-item::before {
  content: '/';
  margin: 0 var(--spacing-sm);
}

.breadcrumb a {
  color: rgba(255, 255, 255, 0.9);
}

.breadcrumb a:hover {
  color: var(--color-white);
}

/* ----------------------------------------
   Sidebar Layout
   ---------------------------------------- */
.page-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: var(--spacing-2xl);
  padding: var(--spacing-2xl) 0;
}

/* 当 page-layout 只有 article 没有 sidebar 时,正文横跨全宽,避免被挤进 280px 那一列 */
.page-layout > article:only-child,
.page-layout > .article-content:only-child {
  grid-column: 1 / -1;
}

.sidebar {
  position: sticky;
  top: 90px;
  height: fit-content;
}

.sidebar-menu {
  background-color: var(--color-bg-light);
  border-radius: var(--radius-lg);
  padding: var(--spacing-md);
}

.sidebar-menu-title {
  font-size: var(--font-size-md);
  font-weight: 600;
  padding: var(--spacing-md);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--spacing-sm);
}

.sidebar-menu-item {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  border-radius: var(--radius-md);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.sidebar-menu-item:hover {
  background-color: var(--color-white);
  color: var(--color-primary);
}

.sidebar-menu-item.active {
  background-color: var(--color-primary);
  color: var(--color-white);
}

.sidebar-contact {
  margin-top: var(--spacing-lg);
  background-color: var(--color-bg-light);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  text-align: center;
}

.sidebar-contact-title {
  font-size: var(--font-size-md);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
}

.sidebar-contact-phone {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: var(--spacing-md);
}

/* ----------------------------------------
   Utility Classes
   ---------------------------------------- */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-primary { color: var(--color-primary); }
.text-accent { color: var(--color-accent); }
.text-secondary { color: var(--color-text-secondary); }
.text-light { color: var(--color-text-light); }

.bg-light { background-color: var(--color-bg-light); }
.bg-gray { background-color: var(--color-bg-gray); }
.bg-white { background-color: var(--color-white); }
.bg-primary { background-color: var(--color-primary); }
.bg-secondary { background-color: var(--color-secondary); }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

.py-1 { padding-top: var(--spacing-sm); padding-bottom: var(--spacing-sm); }
.py-2 { padding-top: var(--spacing-md); padding-bottom: var(--spacing-md); }
.py-3 { padding-top: var(--spacing-lg); padding-bottom: var(--spacing-lg); }
.py-4 { padding-top: var(--spacing-xl); padding-bottom: var(--spacing-xl); }

.px-1 { padding-left: var(--spacing-sm); padding-right: var(--spacing-sm); }
.px-2 { padding-left: var(--spacing-md); padding-right: var(--spacing-md); }
.px-3 { padding-left: var(--spacing-lg); padding-right: var(--spacing-lg); }
.px-4 { padding-left: var(--spacing-xl); padding-right: var(--spacing-xl); }

.hidden { display: none; }
.visible { display: block; }
.invisible { visibility: hidden; }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ----------------------------------------
   Animations
   ---------------------------------------- */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

.animate-fadeIn {
  animation: fadeIn var(--transition-slow) ease-out;
}

.animate-slideUp {
  animation: slideUp var(--transition-slow) ease-out;
}