/* CSS Variables */
:root {
  /* Colors - Light Theme */
  --color-bg: #ffffff;
  --color-bg-secondary: #f8fafc;
  --color-text: #1f2937;
  --color-text-secondary: #6b7280;
  --color-border: #e5e7eb;
  --color-primary: #3b82f6;
  --color-primary-hover: #2563eb;
  --color-success: #10b981;
  --color-error: #ef4444;
  --color-warning: #f59e0b;
  
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  
  /* Typography */
  --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  
  /* Borders */
  --border-radius: 8px;
  --border-width: 1px;
  
  /* Shadows */
  --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);
  
  /* Transitions */
  --transition: all 0.2s ease-in-out;
}

/* Dark Theme */
[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-bg-secondary: #1e293b;
  --color-text: #f1f5f9;
  --color-text-secondary: #94a3b8;
  --color-border: #334155;
  --color-primary: #60a5fa;
  --color-primary-hover: #3b82f6;
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

body {
  font-family: var(--font-sans);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: var(--transition);
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* Header */
.header {
  background-color: var(--color-bg);
  border-bottom: var(--border-width) solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: var(--space-md);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
  color: var(--color-text);
  font-weight: 600;
  font-size: 1.125rem;
}

.logo-icon {
  font-size: 1.5rem;
}

/* Header Navigation */
.header-nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.nav-link {
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
  padding: var(--space-sm) 0;
  border: none;
  background: none;
  cursor: pointer;
  font-size: 0.875rem;
  transition: var(--transition);
}

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

.nav-dropdown {
  position: relative;
}

.dropdown-toggle {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  background-color: var(--color-bg);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-lg);
  padding: var(--space-sm) 0;
  min-width: 200px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: var(--transition);
  z-index: 1000;
}

.nav-dropdown:hover .dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.dropdown-menu a {
  display: block;
  padding: var(--space-sm) var(--space-md);
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.875rem;
  transition: var(--transition);
}

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

.header-search {
  flex: 1;
  max-width: 300px;
}

.search-input {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-size: 0.875rem;
  transition: var(--transition);
}

.search-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.theme-toggle {
  padding: var(--space-sm);
  border: none;
  background: none;
  cursor: pointer;
  border-radius: var(--border-radius);
  font-size: 1.25rem;
  transition: var(--transition);
}

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

/* Main Content */
.main {
  min-height: calc(100vh - 64px);
  padding: var(--space-xl) 0;
}

/* Hero Section */
.hero {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.hero-title {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
  color: var(--color-text);
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-xl);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.trust-indicators {
  display: flex;
  justify-content: center;
  gap: var(--space-xl);
  flex-wrap: wrap;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-weight: 500;
}

.trust-icon {
  font-size: 1.25rem;
}

/* Stats Section */
.stats-section {
  margin-bottom: var(--space-2xl);
  padding: var(--space-xl) 0;
  background-color: var(--color-bg-secondary);
  border-radius: var(--border-radius);
}

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

.stat-item {
  padding: var(--space-lg);
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--space-sm);
}

.stat-label {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  font-weight: 500;
}

/* Section Titles */
.section-title {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: var(--space-2xl);
  color: var(--color-text);
}

/* Tools Grid */
.tools-section {
  margin-bottom: var(--space-2xl);
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-lg);
}

.tool-card {
  padding: var(--space-xl);
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  text-decoration: none;
  color: var(--color-text);
  transition: var(--transition);
  display: block;
}

.tool-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}

.tool-icon {
  font-size: 2.5rem;
  margin-bottom: var(--space-md);
}

.tool-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.tool-description {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  line-height: 1.6;
  margin-bottom: var(--space-md);
}

.tool-features {
  display: flex;
  gap: var(--space-xs);
  flex-wrap: wrap;
}

.feature-tag {
  background-color: var(--color-primary);
  color: white;
  font-size: 0.75rem;
  padding: var(--space-xs) var(--space-sm);
  border-radius: calc(var(--border-radius) / 2);
  font-weight: 500;
}

/* Features Section */
.features-section {
  margin-bottom: var(--space-2xl);
  padding: var(--space-2xl) 0;
  background-color: var(--color-bg-secondary);
  border-radius: var(--border-radius);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-xl);
}

.feature-card {
  text-align: center;
  padding: var(--space-xl);
  background-color: var(--color-bg);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: var(--space-lg);
}

.feature-card h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
  color: var(--color-text);
}

.feature-card p {
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* How It Works Section */
.how-it-works-section {
  margin-bottom: var(--space-2xl);
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-xl);
}

.step-item {
  text-align: center;
  padding: var(--space-lg);
}

.step-number {
  width: 60px;
  height: 60px;
  background-color: var(--color-primary);
  color: white;
  font-size: 1.5rem;
  font-weight: 700;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-md) auto;
}

.step-item h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.step-item p {
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* Educational Section */
.educational-section {
  margin-bottom: var(--space-2xl);
}

.guide-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-lg);
}

.guide-item {
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
}

.guide-item h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.guide-item p {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-md);
  line-height: 1.6;
}

.guide-features {
  font-size: 0.875rem;
  color: var(--color-primary);
}

/* FAQ Section */
.faq-section {
  margin-bottom: var(--space-2xl);
}

.faq-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
  gap: var(--space-lg);
}

.faq-item {
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
}

.faq-item h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.faq-item p {
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.faq-item a {
  color: var(--color-primary);
  text-decoration: none;
}

.faq-item a:hover {
  text-decoration: underline;
}

/* Breadcrumb */
.breadcrumb {
  margin-bottom: var(--space-lg);
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

.breadcrumb a {
  color: var(--color-primary);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

/* Tool Pages */
.tool-header {
  margin-bottom: var(--space-xl);
}

.tool-header h1 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
}

.tool-intro {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  max-width: 800px;
}

/* Converter Interface */
.tool-interface {
  margin-bottom: var(--space-2xl);
}

.converter-layout {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.converter-panel {
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-md);
}

.panel-header h3 {
  font-size: 1.125rem;
  font-weight: 600;
}

.panel-actions {
  display: flex;
  gap: var(--space-sm);
}

.file-upload-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: var(--space-xs) var(--space-sm);
  background-color: var(--color-bg);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  font-size: 0.75rem;
  cursor: pointer;
  transition: var(--transition);
}

.file-upload-btn:hover {
  background-color: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}

.converter-textarea {
  width: 100%;
  height: 300px;
  min-height: 300px;
  padding: var(--space-md);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-mono);
  font-size: 0.875rem;
  line-height: 1.5;
  resize: vertical;
  transition: var(--transition);
}

.converter-textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.converter-textarea.drag-over {
  border-color: var(--color-primary);
  background-color: rgba(59, 130, 246, 0.05);
}

.converter-controls {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: var(--space-sm);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-md);
  border: var(--border-width) solid transparent;
  border-radius: var(--border-radius);
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

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

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

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

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

.btn-small {
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.75rem;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Tool Options */
.tool-options {
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.tool-options h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
}

.options-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-md);
}

.option-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.option-group label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.option-group select,
.option-group input[type="text"],
.option-group input[type="number"] {
  padding: var(--space-xs) var(--space-sm);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-size: 0.875rem;
}

.option-group input[type="checkbox"] {
  margin: 0;
}

/* Error Display */
.error-display {
  background-color: rgba(239, 68, 68, 0.1);
  border: var(--border-width) solid var(--color-error);
  border-radius: var(--border-radius);
  padding: var(--space-md);
  margin: var(--space-md) 0;
  color: var(--color-error);
  font-size: 0.875rem;
}

/* Share Section */
.share-section {
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
}

.share-url {
  width: 100%;
  padding: var(--space-sm);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  margin: var(--space-md) 0;
}

#share-result {
  display: flex;
  gap: var(--space-sm);
  align-items: center;
}

/* Tool Sections */
.tool-section {
  margin-bottom: var(--space-2xl);
}

.tool-section h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
}

.how-to-list {
  padding-left: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.how-to-list li {
  margin-bottom: var(--space-sm);
}

.example {
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
  margin-top: var(--space-md);
}

.example h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
}

.example pre {
  background-color: var(--color-bg);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--space-md);
  margin: var(--space-sm) 0;
  overflow-x: auto;
}

.example code {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--color-text);
}

/* Ad Containers */
.ad-container {
  margin: var(--space-xl) 0;
  text-align: center;
  min-height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg-secondary);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius);
}

/* Footer */
.footer {
  background-color: var(--color-bg-secondary);
  border-top: var(--border-width) solid var(--color-border);
  padding: var(--space-xl) 0;
  margin-top: var(--space-2xl);
}

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

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
}

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

.footer-notice {
  color: var(--color-text-secondary);
  font-size: 0.875rem;
}

.footer-updated {
  margin-top: var(--space-sm);
  font-size: 0.75rem;
}

.tool-footer {
  text-align: center;
  padding-top: var(--space-lg);
  border-top: var(--border-width) solid var(--color-border);
  color: var(--color-text-secondary);
  font-size: 0.875rem;
}

/* Responsive Design */
@media (max-width: 768px) {
  .hero-title {
    font-size: 2rem;
  }
  
  .hero-subtitle {
    font-size: 1rem;
  }
  
  .trust-indicators {
    gap: var(--space-md);
  }
  
  .converter-layout {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }
  
  .converter-controls {
    flex-direction: row;
    justify-content: center;
  }
  
  .options-grid {
    grid-template-columns: 1fr;
  }
  
  .footer-links {
    gap: var(--space-md);
  }
  
  #share-result {
    flex-direction: column;
  }
  
  .container {
    padding: 0 var(--space-sm);
  }
  
  .header-content {
    flex-wrap: wrap;
    gap: var(--space-sm);
  }
  
  .header-nav {
    order: 3;
    flex-basis: 100%;
    justify-content: center;
    gap: var(--space-md);
  }
  
  .header-search {
    order: 2;
    max-width: 200px;
  }
  
  .dropdown-menu {
    position: fixed;
    top: auto;
    left: 50%;
    transform: translateX(-50%);
    width: 90vw;
    max-width: 300px;
  }
  
  .tools-grid {
    grid-template-columns: 1fr;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
  
  .steps-grid {
    grid-template-columns: 1fr;
  }
  
  .guide-grid {
    grid-template-columns: 1fr;
  }
  
  .faq-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .converter-textarea {
    height: 200px;
    min-height: 200px;
  }
  
  .tool-card {
    padding: var(--space-md);
  }
  
  .section-title {
    font-size: 1.5rem;
  }
  
  .stat-number {
    font-size: 2rem;
  }
}

/* Focus and Accessibility */
.btn:focus,
.search-input:focus,
.converter-textarea:focus,
.option-group select:focus,
.option-group input:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Loading States */
.btn.loading {
  opacity: 0.7;
  cursor: wait;
}

.btn.loading::after {
  content: "...";
  animation: dots 1s infinite;
}

@keyframes dots {
  0%, 20% { content: "..."; }
  40% { content: ".."; }
  60% { content: "."; }
  80%, 100% { content: ""; }
}

/* Tooltip */
.tooltip {
  position: relative;
}

.tooltip::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%);
  background-color: var(--color-text);
  color: var(--color-bg);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--border-radius);
  font-size: 0.75rem;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
}

.tooltip:hover::after {
  opacity: 1;
}

/* Dark mode specific adjustments */
[data-theme="dark"] .converter-textarea,
[data-theme="dark"] .search-input,
[data-theme="dark"] .option-group select,
[data-theme="dark"] .option-group input,
[data-theme="dark"] .share-url {
  background-color: var(--color-bg);
}

[data-theme="dark"] .example pre {
  background-color: var(--color-bg-secondary);
}