/* Base Styles & Variables */
:root {
  /* Light Theme Colors */
  --bg-color: #f8fafc;
  --bg-surface: #ffffff;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --success: #10b981;
  --success-hover: #059669;
  --danger: #ef4444;
  --danger-hover: #dc2626;
  --border-color: #e2e8f0;
  
  /* Shadows & Radii */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-glow: 0 0 15px rgba(59, 130, 246, 0.5);
  --radius-sm: 0.375rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-full: 9999px;

  /* Typography */
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Theme */
body.dark-mode {
  --bg-color: #0f172a;
  --bg-surface: #1e293b;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.5;
  transition: background-color var(--transition), color var(--transition);
  -webkit-font-smoothing: antialiased;
}

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

ul {
  list-style: none;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.hidden {
  display: none !important;
}

.mt-2 {
  margin-top: 0.5rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 500;
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: var(--transition);
  outline: none;
}

.btn-full {
  width: 100%;
}

.btn-small {
  padding: 0.4rem 0.8rem;
  font-size: 0.875rem;
}

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

.btn-primary:hover {
  background-color: var(--primary-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

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

.btn-success:hover:not(:disabled) {
  background-color: var(--success-hover);
  transform: translateY(-1px);
}

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

.btn-danger:hover {
  background-color: var(--danger-hover);
}

.btn-secondary {
  background-color: var(--bg-color);
  color: var(--text-main);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  background-color: var(--border-color);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* Header */
.main-header {
  background-color: rgba(var(--bg-surface), 0.8);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.25rem;
}

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

.nav-links {
  display: flex;
  gap: 1.5rem;
  font-weight: 500;
  color: var(--text-muted);
}

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

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

.lang-switcher select {
  padding: 0.5rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background-color: var(--bg-surface);
  color: var(--text-main);
  font-family: inherit;
  cursor: pointer;
  outline: none;
}

.theme-toggle, .mobile-menu-btn {
  background: none;
  border: none;
  font-size: 1.25rem;
  cursor: pointer;
  color: var(--text-main);
  padding: 0.5rem;
  border-radius: var(--radius-full);
  transition: var(--transition);
}

.theme-toggle:hover {
  background-color: var(--border-color);
}

.mobile-menu-btn {
  display: none;
}

/* Content Sections */
.content-section {
  padding: 4rem 0;
  background-color: var(--bg-color);
}

.content-container h2 {
  font-size: 2rem;
  margin-bottom: 1rem;
  text-align: center;
}

.content-container > p {
  text-align: center;
  color: var(--text-muted);
  margin-bottom: 3rem;
}

/* Article Typography */
.article-content {
  max-width: 800px;
  margin: 0 auto;
}

.article-content h2 {
  font-size: 2rem;
  margin-bottom: 1rem;
  color: var(--text-main);
  text-align: left;
}

.article-content h3 {
  font-size: 1.5rem;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  color: var(--text-main);
}

.article-content h4 {
  font-size: 1.2rem;
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
  color: var(--text-main);
}

.article-content p {
  color: var(--text-muted);
  margin-bottom: 1rem;
  text-align: left;
  line-height: 1.6;
}

.article-content ul, .article-content ol {
  margin-bottom: 1.5rem;
  padding-left: 1.5rem;
  color: var(--text-muted);
}

.article-content li {
  margin-bottom: 0.5rem;
  line-height: 1.6;
}

.article-content .feature-list-custom {
  list-style-type: none;
  padding-left: 0;
}

.article-content .feature-list-custom li {
  margin-bottom: 0.5rem;
  color: var(--text-main);
  font-weight: 500;
}

/* Features Grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-bottom: 4rem;
}

.feature-card {
  background-color: var(--bg-surface);
  padding: 2rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  text-align: center;
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.feature-icon {
  font-size: 3rem;
  display: inline-block;
  margin-bottom: 1rem;
}

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

.feature-card p {
  color: var(--text-muted);
}

/* How it works */
.how-it-works {
  background-color: var(--bg-surface);
  padding: 3rem;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  margin-bottom: 4rem;
}

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

.step h3 {
  color: var(--primary);
  margin-bottom: 0.5rem;
}

.step p {
  color: var(--text-muted);
}

/* FAQs */
.faqs {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  padding: 1.5rem;
  border-radius: var(--radius-md);
  margin-bottom: 1rem;
}

.faq-item h4 {
  margin-bottom: 0.5rem;
  font-size: 1.1rem;
}

.faq-item p {
  color: var(--text-muted);
}

/* Footer */
.main-footer {
  background-color: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0;
}

.footer-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
}

.footer-brand .copyright {
  color: var(--text-muted);
  margin-top: 0.5rem;
  font-size: 0.875rem;
  text-align: center;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1.5rem;
  color: var(--text-muted);
}

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

/* Mobile Responsiveness */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .mobile-menu-btn {
    display: block;
  }
  .content-section {
    padding: 2rem 0;
  }
}