/* ===== CSS Custom Properties (Theme System) ===== */
:root {
  /* Default to dark theme */
  --bg-primary: #0d0d0d;
  --bg-secondary: #1a1a1a;
  --bg-tertiary: #252525;
  --text-primary: #f0f0f0;
  --text-secondary: #b0b0b0;
  --accent-primary: #00ff88;
  --accent-primary-hover: #00cc6a;
  --accent-secondary: #0088ff;
  --accent-secondary-hover: #0066cc;
  --border-color: #333;
  --shadow-color: rgba(0, 0, 0, 0.3);

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-xxl: 5rem;

  /* Typography */
  --font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.25rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 2.5rem;
  --font-size-4xl: 3.5rem;

  /* Layout */
  --max-width: 1200px;
  --header-height: 70px;
  --border-radius: 8px;
  --transition-speed: 0.3s;
}

/* Light Theme */
[data-theme="light"] {
  --bg-primary: #ffffff;
  --bg-secondary: #f5f5f5;
  --bg-tertiary: #e8e8e8;
  --text-primary: #1a1a1a;
  --text-secondary: #555555;
  --accent-primary: #00aa55;
  --accent-primary-hover: #008844;
  --accent-secondary: #0055aa;
  --accent-secondary-hover: #004488;
  --border-color: #ddd;
  --shadow-color: rgba(0, 0, 0, 0.1);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-speed), color var(--transition-speed);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

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

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

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

ul {
  list-style: none;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-sm);
}

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); }

p {
  margin-bottom: var(--spacing-sm);
}

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

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

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.section-title h2 {
  margin-bottom: var(--spacing-xs);
}

.section-title p {
  color: var(--text-secondary);
  font-size: var(--font-size-lg);
}

/* ===== Header & Navigation ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: background-color var(--transition-speed);
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.logo span {
  color: var(--accent-primary);
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
}

.nav-links {
  display: flex;
  gap: var(--spacing-md);
}

.nav-links a {
  color: var(--text-primary);
  font-weight: 500;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius);
  transition: color var(--transition-speed), background-color var(--transition-speed);
}

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

/* Mobile Menu Button */
.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
}

.mobile-menu-btn span {
  display: block;
  width: 25px;
  height: 3px;
  background-color: var(--text-primary);
  border-radius: 2px;
  transition: transform var(--transition-speed), opacity var(--transition-speed);
}

.mobile-menu-btn.active span:nth-child(1) {
  transform: rotate(45deg) translate(6px, 6px);
}

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

.mobile-menu-btn.active span:nth-child(3) {
  transform: rotate(-45deg) translate(6px, -6px);
}

/* Theme Toggle - Yin/Yang Style */
.theme-toggle {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 2px solid var(--border-color);
  background: linear-gradient(to right, var(--bg-primary) 50%, var(--text-primary) 50%);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  transition: transform var(--transition-speed), border-color var(--transition-speed);
}

.theme-toggle:hover {
  transform: rotate(180deg);
  border-color: var(--accent-primary);
}

.theme-toggle::before,
.theme-toggle::after {
  content: '';
  position: absolute;
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.theme-toggle::before {
  top: 5px;
  left: 50%;
  transform: translateX(-50%);
  background-color: var(--text-primary);
}

.theme-toggle::after {
  bottom: 5px;
  left: 50%;
  transform: translateX(-50%);
  background-color: var(--bg-primary);
}

/* ===== Hero Section ===== */
.hero {
  min-height: calc(100vh - var(--header-height));
  display: flex;
  align-items: center;
  padding-top: var(--header-height);
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at 30% 50%, rgba(0, 255, 136, 0.1) 0%, transparent 50%),
              radial-gradient(circle at 70% 80%, rgba(0, 136, 255, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

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

.hero h1 {
  margin-bottom: var(--spacing-md);
}

.hero h1 span {
  color: var(--accent-primary);
}

.hero p {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
}

.hero-buttons {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: var(--font-size-base);
  font-weight: 600;
  border-radius: var(--border-radius);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-speed);
  text-decoration: none;
}

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

.btn-primary:hover {
  background-color: var(--accent-primary-hover);
  color: var(--bg-primary);
}

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

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

/* ===== Cards ===== */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-lg);
}

.card {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius);
  padding: var(--spacing-lg);
  border: 1px solid var(--border-color);
  transition: transform var(--transition-speed), box-shadow var(--transition-speed), background-color var(--transition-speed);
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px var(--shadow-color);
}

.card-icon {
  width: 60px;
  height: 60px;
  background-color: var(--bg-tertiary);
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-md);
  font-size: var(--font-size-2xl);
}

.card h3 {
  margin-bottom: var(--spacing-xs);
}

.card p {
  color: var(--text-secondary);
  margin-bottom: 0;
}

/* ===== CTA Banner ===== */
.cta-banner {
  background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
  padding: var(--spacing-xl) 0;
  text-align: center;
}

.cta-banner h2 {
  color: var(--bg-primary);
  margin-bottom: var(--spacing-sm);
}

.cta-banner p {
  color: var(--bg-primary);
  opacity: 0.9;
  margin-bottom: var(--spacing-md);
}

.cta-banner .btn {
  background-color: var(--bg-primary);
  color: var(--accent-primary);
  border-color: var(--bg-primary);
}

.cta-banner .btn:hover {
  background-color: transparent;
  color: var(--bg-primary);
}

/* ===== Features Section ===== */
.features {
  background-color: var(--bg-secondary);
}

/* ===== Product Highlight ===== */
.product-highlight {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-xl);
  align-items: center;
}

.product-image {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius);
  padding: var(--spacing-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 300px;
  border: 1px solid var(--border-color);
}

.product-image-placeholder {
  width: 200px;
  height: 200px;
  background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
}

.product-content h3 {
  color: var(--accent-primary);
  font-size: var(--font-size-sm);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: var(--spacing-xs);
}

.product-content h2 {
  margin-bottom: var(--spacing-md);
}

.product-content p {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-md);
}

.product-features {
  margin-bottom: var(--spacing-lg);
}

.product-features li {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xs);
  color: var(--text-secondary);
}

.product-features li::before {
  content: '✓';
  color: var(--accent-primary);
  font-weight: bold;
}

/* ===== About Page Styles ===== */
.page-hero {
  padding: calc(var(--header-height) + var(--spacing-xxl)) 0 var(--spacing-xxl);
  background-color: var(--bg-secondary);
  text-align: center;
}

.page-hero h1 {
  margin-bottom: var(--spacing-sm);
}

.page-hero p {
  color: var(--text-secondary);
  font-size: var(--font-size-lg);
  max-width: 600px;
  margin: 0 auto;
}

.mission-section {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-xl);
}

.mission-box {
  background-color: var(--bg-secondary);
  padding: var(--spacing-xl);
  border-radius: var(--border-radius);
  border: 1px solid var(--border-color);
}

.mission-box h3 {
  color: var(--accent-primary);
  margin-bottom: var(--spacing-sm);
}

.values-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
}

.value-card {
  text-align: center;
  padding: var(--spacing-lg);
}

.value-icon {
  width: 80px;
  height: 80px;
  background-color: var(--bg-secondary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--spacing-md);
  font-size: 2rem;
  border: 2px solid var(--border-color);
}

.value-card h3 {
  margin-bottom: var(--spacing-xs);
}

.value-card p {
  color: var(--text-secondary);
}

.impact-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-lg);
  text-align: center;
}

.stat-item h3 {
  font-size: var(--font-size-4xl);
  color: var(--accent-primary);
  margin-bottom: var(--spacing-xs);
}

.stat-item p {
  color: var(--text-secondary);
}

/* ===== Products Page Styles ===== */
.product-category {
  margin-bottom: var(--spacing-xxl);
}

.product-category:last-child {
  margin-bottom: 0;
}

.category-header {
  margin-bottom: var(--spacing-lg);
}

.category-header h3 {
  color: var(--accent-primary);
  margin-bottom: var(--spacing-xs);
}

.product-card {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius);
  overflow: hidden;
  border: 1px solid var(--border-color);
  transition: transform var(--transition-speed), box-shadow var(--transition-speed);
}

.product-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px var(--shadow-color);
}

.product-card-image {
  height: 200px;
  background: linear-gradient(135deg, var(--bg-tertiary) 0%, var(--bg-secondary) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
  border-bottom: 1px solid var(--border-color);
}

.product-card-content {
  padding: var(--spacing-lg);
}

.product-card h4 {
  margin-bottom: var(--spacing-xs);
}

.product-card p {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-md);
}

.use-cases {
  background-color: var(--bg-secondary);
}

.use-case-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
}

.use-case-card {
  background-color: var(--bg-primary);
  padding: var(--spacing-lg);
  border-radius: var(--border-radius);
  border: 1px solid var(--border-color);
}

.use-case-card h4 {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-sm);
}

.use-case-card p {
  color: var(--text-secondary);
  margin-bottom: 0;
}

/* ===== Contact Page Styles ===== */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-xl);
}

.contact-form {
  background-color: var(--bg-secondary);
  padding: var(--spacing-xl);
  border-radius: var(--border-radius);
  border: 1px solid var(--border-color);
}

.form-group {
  margin-bottom: var(--spacing-md);
}

.form-group label {
  display: block;
  margin-bottom: var(--spacing-xs);
  font-weight: 500;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: var(--spacing-sm);
  font-size: var(--font-size-base);
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  color: var(--text-primary);
  transition: border-color var(--transition-speed), box-shadow var(--transition-speed);
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(0, 255, 136, 0.1);
}

.form-group textarea {
  resize: vertical;
  min-height: 150px;
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--text-secondary);
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.info-card {
  background-color: var(--bg-secondary);
  padding: var(--spacing-lg);
  border-radius: var(--border-radius);
  border: 1px solid var(--border-color);
}

.info-card h4 {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-sm);
  color: var(--accent-primary);
}

.info-card p {
  color: var(--text-secondary);
  margin-bottom: 0;
}

.info-card a {
  color: var(--text-primary);
}

.info-card a:hover {
  color: var(--accent-primary);
}

/* ===== Footer ===== */
.footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: var(--spacing-xl) 0 var(--spacing-lg);
  margin-top: auto;
}

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

.footer-brand p {
  color: var(--text-secondary);
  margin-top: var(--spacing-sm);
}

.footer-column h4 {
  font-size: var(--font-size-base);
  margin-bottom: var(--spacing-md);
}

.footer-column ul li {
  margin-bottom: var(--spacing-xs);
}

.footer-column a {
  color: var(--text-secondary);
}

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

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--border-color);
}

.footer-bottom p {
  color: var(--text-secondary);
  margin: 0;
}

.social-links {
  display: flex;
  gap: var(--spacing-sm);
}

.social-links a {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--bg-tertiary);
  border-radius: 50%;
  color: var(--text-primary);
  transition: background-color var(--transition-speed), color var(--transition-speed);
}

.social-links a:hover {
  background-color: var(--accent-primary);
  color: var(--bg-primary);
}

/* ===== Responsive Styles ===== */
@media (max-width: 1024px) {
  .product-highlight {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 768px) {
  :root {
    --font-size-4xl: 2.5rem;
    --font-size-3xl: 2rem;
    --font-size-2xl: 1.5rem;
  }

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

  .nav-links {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background-color: var(--bg-secondary);
    flex-direction: column;
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
    gap: 0;
  }

  .nav-links.active {
    display: flex;
  }

  .nav-links a {
    padding: var(--spacing-sm);
    border-bottom: 1px solid var(--border-color);
  }

  .nav-links a:last-child {
    border-bottom: none;
  }

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

  .mission-section {
    grid-template-columns: 1fr;
  }

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

  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .footer-bottom {
    flex-direction: column;
    gap: var(--spacing-md);
    text-align: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--spacing-sm);
  }

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