/* =================================================================
   NANJING SASHA TECHNOLOGY - Global Styles
   Premium Corporate Website with Tesla-inspired Design
   ================================================================= */

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

:root {
  --primary-color: #000;
  --secondary-color: #f1f1f1;
  --accent-color: #3b82f6;
  --text-dark: #1a1a1a;
  --text-light: #666;
  --bg-light: #ffffff;
  --bg-dark: #0a0a0a;
  --border-color: #e5e7eb;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
    sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  color: var(--text-dark);
  background-color: var(--bg-light);
  line-height: 1.6;
  overflow-x: hidden;
}

/* =================================================================
   HEADER & NAVIGATION
   ================================================================= */

header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition);
}

header.scrolled {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  background: rgba(255, 255, 255, 0.98);
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  max-width: 100%;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -1px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo svg {
  width: 32px;
  height: 32px;
  transition: var(--transition);
}

.logo:hover svg {
  transform: scale(1.1);
}

nav ul {
  display: flex;
  list-style: none;
  gap: 2rem;
}

nav a {
  text-decoration: none;
  color: var(--text-dark);
  font-weight: 500;
  font-size: 0.95rem;
  position: relative;
  transition: var(--transition);
}

nav a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent-color);
  transition: width 0.3s ease;
}

nav a:hover::after {
  width: 100%;
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.5rem;
}

/* =================================================================
   HERO SECTION
   ================================================================= */

.hero {
  margin-top: 60px;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #ffffff 0%, #f9fafb 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(59, 130, 246, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  top: -200px;
  right: -200px;
  animation: float 6s ease-in-out infinite;
}

.hero::after {
  content: '';
  position: absolute;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(59, 130, 246, 0.08) 0%, transparent 70%);
  border-radius: 50%;
  bottom: -100px;
  left: -100px;
  animation: float 8s ease-in-out infinite reverse;
}

@keyframes float {
  0%, 100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(30px);
  }
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 900px;
  padding: 2rem;
  animation: fadeInUp 0.8s ease 0.2s both;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, #000 0%, #333 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-light);
  margin-bottom: 2.5rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero-buttons {
  display: flex;
  gap: 1.5rem;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  padding: 1rem 2.5rem;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
  display: inline-block;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.2);
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn-primary {
  background: var(--primary-color);
  color: white;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
}

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

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

/* =================================================================
   SECTIONS
   ================================================================= */

section {
  padding: 5rem 2rem;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 1rem;
  animation: fadeIn 0.6s ease;
}

.section-subtitle {
  font-size: 1.1rem;
  color: var(--text-light);
  text-align: center;
  margin-bottom: 3rem;
}

/* =================================================================
   SERVICES SECTION
   ================================================================= */

.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.service-card {
  background: var(--bg-light);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  padding: 2rem;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--accent-color), #60a5fa);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.5s ease;
}

.service-card:hover {
  border-color: var(--accent-color);
  box-shadow: 0 20px 40px rgba(59, 130, 246, 0.1);
  transform: translateY(-5px);
}

.service-card:hover::before {
  transform: scaleX(1);
}

.service-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  display: inline-block;
  transition: var(--transition);
}

.service-card:hover .service-icon {
  transform: scale(1.2) rotate(5deg);
}

.service-card h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

.service-card p {
  color: var(--text-light);
  line-height: 1.8;
}

/* =================================================================
   FEATURES SECTION
   ================================================================= */

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

.features .section-title {
  color: white;
}

.features .section-subtitle {
  color: #aaa;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.feature-item {
  text-align: center;
  padding: 2rem;
  transition: var(--transition);
}

.feature-item:hover {
  transform: translateY(-10px);
}

.feature-icon {
  width: 80px;
  height: 80px;
  background: rgba(59, 130, 246, 0.2);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1.5rem;
  font-size: 2rem;
  transition: var(--transition);
}

.feature-item:hover .feature-icon {
  background: rgba(59, 130, 246, 0.4);
  transform: scale(1.1) rotate(10deg);
}

.feature-item h3 {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.feature-item p {
  color: #999;
  font-size: 0.95rem;
}

/* =================================================================
   MOBILE APP SECTION
   ================================================================= */

.mobile-app {
  background: linear-gradient(135deg, #f9fafb 0%, #ffffff 100%);
}

.app-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.app-image {
  text-align: center;
  animation: slideInRight 0.8s ease;
}

.app-image svg {
  max-width: 100%;
  height: auto;
  filter: drop-shadow(0 20px 40px rgba(0, 0, 0, 0.1));
}

.app-description h2 {
  font-size: 2rem;
  margin-bottom: 1.5rem;
}

.app-description p {
  color: var(--text-light);
  margin-bottom: 1.5rem;
  line-height: 1.8;
}

.app-features {
  margin: 2rem 0;
}

.app-features li {
  list-style: none;
  padding: 0.75rem 0;
  padding-left: 2rem;
  position: relative;
  color: var(--text-light);
}

.app-features li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--accent-color);
  font-weight: bold;
  font-size: 1.2rem;
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(50px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.store-badges {
  display: flex;
  gap: 1.5rem;
  margin-top: 2rem;
}

.store-badge {
  display: inline-block;
  padding: 0.8rem 1.5rem;
  background: var(--primary-color);
  color: white;
  border-radius: 0.5rem;
  text-decoration: none;
  font-size: 0.9rem;
  transition: var(--transition);
}

.store-badge:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
}

/* =================================================================
   STATS SECTION
   ================================================================= */

.stats {
  background: var(--primary-color);
  color: white;
}

.stats .section-title {
  color: white;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.stat-item {
  text-align: center;
  padding: 2rem;
  border-left: 3px solid var(--accent-color);
  animation: slideUp 0.6s ease;
}

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

.stat-number {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  background: linear-gradient(135deg, #60a5fa, #93c5fd);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-label {
  font-size: 1rem;
  color: #bbb;
}

/* =================================================================
   CULTURE SECTION
   ================================================================= */

.culture-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.culture-card {
  background: var(--bg-light);
  border-radius: 1rem;
  overflow: hidden;
  transition: var(--transition);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
}

.culture-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
}

.culture-image {
  width: 100%;
  height: 200px;
  background: linear-gradient(135deg, var(--accent-color), #60a5fa);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  overflow: hidden;
}

.culture-image svg {
  width: 80%;
  height: 80%;
}

.culture-content {
  padding: 1.5rem;
}

.culture-content h3 {
  font-size: 1.3rem;
  margin-bottom: 0.5rem;
}

.culture-content p {
  color: var(--text-light);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* =================================================================
   NEWS/BLOG SECTION
   ================================================================= */

.news-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.news-card {
  background: var(--bg-light);
  border-radius: 1rem;
  overflow: hidden;
  transition: var(--transition);
  border: 1px solid var(--border-color);
}

.news-card:hover {
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
  transform: translateY(-5px);
}

.news-date {
  padding: 1rem;
  background: var(--accent-color);
  color: white;
  font-size: 0.9rem;
  font-weight: 600;
}

.news-content {
  padding: 1.5rem;
}

.news-content h3 {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.news-excerpt {
  color: var(--text-light);
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 1rem;
}

.read-more {
  color: var(--accent-color);
  text-decoration: none;
  font-weight: 600;
  transition: var(--transition);
}

.read-more:hover {
  gap: 0.5rem;
  display: inline-flex;
  align-items: center;
}

/* =================================================================
   CONTACT SECTION
   ================================================================= */

.contact {
  background: linear-gradient(135deg, var(--bg-dark) 0%, #1a1a1a 100%);
  color: white;
}

.contact .section-title {
  color: white;
}

.contact .section-subtitle {
  color: #aaa;
}

.contact-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  margin-top: 3rem;
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.contact-item {
  display: flex;
  gap: 1.5rem;
  animation: fadeIn 0.6s ease;
}

.contact-icon {
  width: 50px;
  height: 50px;
  background: rgba(59, 130, 246, 0.2);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  flex-shrink: 0;
}

.contact-details h3 {
  margin-bottom: 0.25rem;
  color: var(--accent-color);
}

.contact-details p {
  color: #ccc;
}

.contact-details a {
  color: var(--accent-color);
  text-decoration: none;
  transition: var(--transition);
}

.contact-details a:hover {
  text-decoration: underline;
}

.contact-form {
  background: rgba(255, 255, 255, 0.05);
  padding: 2rem;
  border-radius: 1rem;
  border: 1px solid rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
}

.contact-form h3 {
  margin-bottom: 1.5rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
  font-weight: 500;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.8rem;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 0.5rem;
  color: white;
  font-family: inherit;
  transition: var(--transition);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: rgba(255, 255, 255, 0.5);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  background: rgba(255, 255, 255, 0.15);
  border-color: var(--accent-color);
  box-shadow: 0 0 20px rgba(59, 130, 246, 0.3);
}

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

.form-submit {
  width: 100%;
  padding: 1rem;
  background: var(--accent-color);
  color: white;
  border: none;
  border-radius: 0.5rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.form-submit:hover {
  background: #2563eb;
  transform: translateY(-2px);
  box-shadow: 0 10px 25px rgba(59, 130, 246, 0.3);
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

/* =================================================================
   FOOTER
   ================================================================= */

footer {
  background: var(--primary-color);
  color: #aaa;
  padding: 2rem 2rem 1rem;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.footer-section h4 {
  color: white;
  margin-bottom: 0.75rem;
  font-size: 0.95rem;
  font-weight: 600;
}

.footer-section p {
  font-size: 0.85rem;
  line-height: 1.5;
}

.footer-section ul {
  list-style: none;
}

.footer-section ul li {
  margin-bottom: 0.5rem;
}

.footer-section ul li a {
  color: #aaa;
  text-decoration: none;
  transition: var(--transition);
  font-size: 0.85rem;
}

.footer-section ul li a:hover {
  color: var(--accent-color);
}

.footer-social {
  display: flex;
  gap: 0.75rem;
}

.social-icon {
  width: 32px;
  height: 32px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  color: white;
  transition: var(--transition);
  font-size: 0.8rem;
}

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

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  font-size: 0.8rem;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
}

.footer-links a {
  color: #aaa;
  text-decoration: none;
  font-size: 0.8rem;
  transition: var(--transition);
}

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

/* =================================================================
   RESPONSIVE DESIGN
   ================================================================= */

@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }

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

  nav ul {
    display: none;
  }

  .mobile-menu-btn {
    display: block;
  }

  nav.mobile-open ul {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: white;
    padding: 1rem;
    gap: 0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  }

  nav.mobile-open a {
    padding: 0.75rem 0;
    display: block;
  }

  .hero-buttons {
    flex-direction: column;
  }

  .app-content {
    grid-template-columns: 1fr;
  }

  .contact-container {
    grid-template-columns: 1fr;
  }

  section {
    padding: 3rem 1rem;
  }

  .section-title {
    font-size: 1.8rem;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.5rem;
  }

  .hero-buttons {
    gap: 1rem;
  }

  .btn {
    padding: 0.75rem 1.5rem;
    font-size: 0.9rem;
  }

  .navbar {
    padding: 0.75rem 1rem;
  }

  nav ul {
    gap: 1rem;
  }

  .services-grid,
  .features-grid,
  .news-grid {
    grid-template-columns: 1fr;
  }

  .store-badges {
    flex-direction: column;
  }
}

/* =================================================================
   SCROLL ANIMATIONS
   ================================================================= */

.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: var(--transition-slow);
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* =================================================================
   UTILITY CLASSES
   ================================================================= */

.text-center {
  text-align: center;
}

.mt-3 {
  margin-top: 1.5rem;
}

.mb-3 {
  margin-bottom: 1.5rem;
}

.gap-2 {
  gap: 1rem;
}