/* CSS Custom Properties for Design System */
:root {
  /* Color Palette */
  --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --primary-color: #667eea;
  --primary-dark: #5a67d8;
  --secondary-color: #10b981;
  --accent-color: #f59e0b;
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  
  /* Neutral Colors - Light Mode */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --border-color: #e5e7eb;
  --shadow-light: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --shadow-medium: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-large: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  
  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Transitions */
  --transition-fast: 0.15s ease-out;
  --transition-normal: 0.25s ease-out;
  --transition-slow: 0.35s ease-out;
  
  /* Z-index levels */
  --z-dropdown: 1000;
  --z-toast: 2000;
  --z-modal: 3000;
}

/* Dark Mode Variables */
[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border-color: #475569;
  --shadow-light: 0 1px 3px 0 rgba(0, 0, 0, 0.3);
  --shadow-medium: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
  --shadow-large: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
}

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

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

body {
  font-family: var(--font-family);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  min-height: 100vh;
}

/* Theme Toggle */
.theme-toggle {
  position: fixed;
  top: 1rem;
  right: 1rem;
  z-index: var(--z-dropdown);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 0.75rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-medium);
}

.theme-toggle:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-large);
}

.theme-icon {
  width: 1.25rem;
  height: 1.25rem;
  color: var(--text-primary);
  transition: all var(--transition-fast);
}

.moon-icon {
  display: none;
}

[data-theme="dark"] .sun-icon {
  display: none;
}

[data-theme="dark"] .moon-icon {
  display: block;
}

/* Language Selector */
.language-selector {
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: var(--z-dropdown);
}

.lang-toggle {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 0.75rem 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-medium);
  font-size: 0.875rem;
  font-weight: 500;
}

.lang-toggle:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-large);
}

.chevron-down {
  width: 1rem;
  height: 1rem;
  transition: transform var(--transition-fast);
}

.language-selector.active .chevron-down {
  transform: rotate(180deg);
}

.lang-dropdown {
  position: absolute;
  top: calc(100% + 0.5rem);
  left: 0;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-large);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: all var(--transition-normal);
  min-width: 150px;
}

.language-selector.active .lang-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.lang-option {
  width: 100%;
  padding: 0.75rem 1rem;
  background: none;
  border: none;
  text-align: left;
  cursor: pointer;
  transition: background-color var(--transition-fast);
  font-size: 0.875rem;
  color: var(--text-primary);
}

.lang-option:hover {
  background: var(--bg-tertiary);
}

.lang-option:first-child {
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}

.lang-option:last-child {
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

/* Main Container */
.container {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--spacing-xl) var(--spacing-md);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-2xl);
}

/* Header */
.header {
  text-align: center;
  margin-top: var(--spacing-xl);
}

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

.logo-icon {
  width: 3rem;
  height: 3rem;
  color: var(--primary-color);
  filter: drop-shadow(0 2px 4px rgba(102, 126, 234, 0.2));
}

.logo-text {
  text-align: left;
}

.app-title {
  font-size: 2.5rem;
  font-weight: 700;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.25rem;
}

.app-subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.app-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* Generator Panel */
.generator-panel {
  background: var(--bg-secondary);
  border-radius: var(--radius-xl);
  padding: var(--spacing-2xl);
  box-shadow: var(--shadow-medium);
  border: 1px solid var(--border-color);
  transition: all var(--transition-normal);
}

.generator-panel:hover {
  box-shadow: var(--shadow-large);
}

.control-group {
  margin-bottom: var(--spacing-xl);
}

.control-label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
  font-size: 1.125rem;
}

.length-control {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.length-slider {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 8px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  outline: none;
  cursor: pointer;
}

.length-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 24px;
  height: 24px;
  background: var(--primary-gradient);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: var(--shadow-medium);
  transition: all var(--transition-fast);
}

.length-slider::-webkit-slider-thumb:hover {
  transform: scale(1.1);
  box-shadow: var(--shadow-large);
}

.length-slider::-moz-range-thumb {
  width: 24px;
  height: 24px;
  background: var(--primary-gradient);
  border-radius: 50%;
  cursor: pointer;
  border: none;
  box-shadow: var(--shadow-medium);
}

.length-display {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--primary-color);
  min-width: 3rem;
  text-align: center;
  background: var(--bg-primary);
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

/* Options Grid */
.options-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}

.option-item {
  position: relative;
}

.option-item input[type="checkbox"] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.option-label {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md) var(--spacing-lg);
  background: var(--bg-primary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

.option-label:hover {
  border-color: var(--primary-color);
  transform: translateY(-1px);
  box-shadow: var(--shadow-medium);
}

.option-item input:checked + .option-label {
  border-color: var(--primary-color);
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
}

.option-icon {
  font-size: 1.25rem;
  width: 2rem;
  text-align: center;
}

.option-text {
  font-weight: 500;
  color: var(--text-primary);
}

/* Generate Button */
.generate-btn {
  width: 100%;
  background: var(--primary-gradient);
  color: white;
  border: none;
  border-radius: var(--radius-lg);
  padding: 1rem 2rem;
  font-size: 1.125rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-md);
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-medium);
  position: relative;
  overflow: hidden;
}

.generate-btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: left var(--transition-slow);
}

.generate-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-large);
}

.generate-btn:hover::before {
  left: 100%;
}

.generate-btn:active {
  transform: translateY(0);
}

.btn-icon {
  width: 1.25rem;
  height: 1.25rem;
  transition: transform var(--transition-fast);
}

.generate-btn:hover .btn-icon {
  transform: rotate(180deg);
}

/* Password Section */
.password-section {
  background: var(--bg-secondary);
  border-radius: var(--radius-xl);
  padding: var(--spacing-2xl);
  box-shadow: var(--shadow-medium);
  border: 1px solid var(--border-color);
}

.password-container {
  position: relative;
  margin-bottom: var(--spacing-lg);
}

.password-field {
  width: 100%;
  padding: 1rem 3.5rem 1rem 1rem;
  font-family: var(--font-mono);
  font-size: 1.125rem;
  background: var(--bg-primary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  outline: none;
  transition: all var(--transition-fast);
  word-break: break-all;
  color: var(--text-primary);
}

.password-field:focus {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.copy-btn {
  position: absolute;
  right: 0.5rem;
  top: 50%;
  transform: translateY(-50%);
  background: var(--primary-gradient);
  border: none;
  border-radius: var(--radius-md);
  padding: 0.75rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  color: white;
}

.copy-btn:hover {
  transform: translateY(-50%) scale(1.05);
}

.copy-icon,
.check-icon {
  width: 1rem;
  height: 1rem;
  transition: all var(--transition-fast);
}

.check-icon {
  display: none;
}

.copy-btn.copied .copy-icon {
  display: none;
}

.copy-btn.copied .check-icon {
  display: block;
}

/* Strength Indicator */
.strength-indicator {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.strength-label {
  font-weight: 600;
  color: var(--text-primary);
}

.strength-bar {
  flex: 1;
  height: 8px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.strength-fill {
  height: 100%;
  border-radius: var(--radius-md);
  transition: all var(--transition-normal);
  width: 0;
}

.strength-fill.weak {
  width: 25%;
  background: var(--danger-color);
}

.strength-fill.fair {
  width: 50%;
  background: var(--warning-color);
}

.strength-fill.good {
  width: 75%;
  background: var(--secondary-color);
}

.strength-fill.strong {
  width: 100%;
  background: var(--secondary-color);
}

.strength-text {
  font-weight: 600;
  min-width: 4rem;
}

.strength-text.weak {
  color: var(--danger-color);
}

.strength-text.fair {
  color: var(--warning-color);
}

.strength-text.good,
.strength-text.strong {
  color: var(--secondary-color);
}

/* History Section */
.history-section {
  background: var(--bg-secondary);
  border-radius: var(--radius-xl);
  border: 1px solid var(--border-color);
  overflow: hidden;
  box-shadow: var(--shadow-medium);
}

.history-toggle {
  width: 100%;
  background: none;
  border: none;
  padding: var(--spacing-lg) var(--spacing-xl);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--text-primary);
  font-size: 1.125rem;
  font-weight: 600;
}

.history-toggle:hover {
  background: var(--bg-tertiary);
}

.history-icon {
  width: 1.25rem;
  height: 1.25rem;
}

.chevron {
  width: 1rem;
  height: 1rem;
  margin-left: auto;
  transition: transform var(--transition-fast);
}

.history-section.expanded .chevron {
  transform: rotate(180deg);
}

.history-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow);
}

.history-section.expanded .history-content {
  max-height: 600px;
}

.history-actions {
  padding: 0 var(--spacing-xl) var(--spacing-lg);
  border-bottom: 1px solid var(--border-color);
}

.clear-history-btn {
  background: var(--danger-color);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.clear-history-btn:hover {
  background: #dc2626;
  transform: translateY(-1px);
}

.history-list {
  padding: var(--spacing-lg) var(--spacing-xl);
  max-height: 400px;
  overflow-y: auto;
}

.history-empty {
  text-align: center;
  color: var(--text-muted);
  font-style: italic;
  padding: var(--spacing-xl) 0;
}

.history-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md);
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-sm);
  transition: all var(--transition-fast);
}

.history-item:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-medium);
}

.history-password {
  font-family: var(--font-mono);
  flex: 1;
  font-size: 0.875rem;
  color: var(--text-primary);
  word-break: break-all;
}

.history-meta {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0.25rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.history-copy {
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  padding: 0.5rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.history-copy:hover {
  background: var(--primary-dark);
}

/* Footer */
.footer {
  text-align: center;
  margin-top: auto;
  padding-top: var(--spacing-2xl);
  border-top: 1px solid var(--border-color);
}

.footer-text {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: var(--spacing-sm);
  color: var(--text-secondary);
}

.heart {
  color: var(--danger-color);
  animation: heartbeat 2s ease-in-out infinite;
}

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

@keyframes heartbeat {
  0%, 50%, 100% { transform: scale(1); }
  25%, 75% { transform: scale(1.1); }
}

/* Toast Notification */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--bg-secondary);
  color: var(--text-primary);
  padding: 1rem 1.5rem;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  box-shadow: var(--shadow-large);
  border: 1px solid var(--border-color);
  opacity: 0;
  transition: all var(--transition-normal);
  z-index: var(--z-toast);
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.toast-icon {
  width: 1.25rem;
  height: 1.25rem;
  color: var(--secondary-color);
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: var(--spacing-lg) var(--spacing-md);
    gap: var(--spacing-xl);
  }
  
  .theme-toggle,
  .language-selector {
    top: 0.5rem;
  }
  
  .theme-toggle {
    right: 0.5rem;
  }
  
  .language-selector {
    left: 0.5rem;
  }
  
  .header {
    margin-top: var(--spacing-lg);
  }
  
  .logo {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
  
  .logo-text {
    text-align: center;
  }
  
  .app-title {
    font-size: 2rem;
  }
  
  .generator-panel,
  .password-section,
  .history-section {
    padding: var(--spacing-lg);
  }
  
  .options-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-sm);
  }
  
  .option-label {
    padding: var(--spacing-md);
  }
  
  .length-control {
    flex-direction: column;
    align-items: stretch;
    gap: var(--spacing-sm);
  }
  
  .length-display {
    align-self: center;
  }
  
  .strength-indicator {
    flex-direction: column;
    align-items: stretch;
    gap: var(--spacing-sm);
  }
  
  .strength-label {
    text-align: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: var(--spacing-md) var(--spacing-sm);
  }
  
  .app-title {
    font-size: 1.75rem;
  }
  
  .app-subtitle {
    font-size: 1rem;
  }
  
  .password-field {
    font-size: 1rem;
  }
  
  .history-item {
    flex-direction: column;
    align-items: stretch;
    gap: var(--spacing-sm);
  }
  
  .history-meta {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }
}

/* Focus Styles for Accessibility */
*:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

button:focus,
input:focus {
  outline: none;
}

button:focus-visible,
input:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
  :root {
    --border-color: #000000;
    --text-muted: var(--text-secondary);
  }
  
  [data-theme="dark"] {
    --border-color: #ffffff;
  }
}

/* Print Styles */
@media print {
  .theme-toggle,
  .language-selector,
  .generate-btn,
  .copy-btn,
  .history-section,
  .toast {
    display: none !important;
  }
  
  body {
    background: white !important;
    color: black !important;
  }
  
  .password-field {
    border: 1px solid black !important;
    background: white !important;
  }
}

/* Touch Feedback Styles */
.touch-active {
  transform: scale(0.98) !important;
  opacity: 0.8 !important;
  transition: all 0.1s ease-out !important;
}

/* Enhanced Mobile Touch Targets */
@media (max-width: 768px) {
  /* Ensure all interactive elements are at least 44px */
  button,
  input[type="checkbox"] + label,
  .lang-option {
    min-height: 44px;
    min-width: 44px;
  }
  
  /* Better spacing for touch */
  .options-grid {
    gap: var(--spacing-lg);
  }
  
  .option-label {
    padding: var(--spacing-lg);
    min-height: 60px;
  }
  
  /* Larger slider thumb on mobile */
  .length-slider::-webkit-slider-thumb {
    width: 28px;
    height: 28px;
  }
  
  .length-slider::-moz-range-thumb {
    width: 28px;
    height: 28px;
  }
  
  /* Better toast positioning on mobile */
  .toast {
    bottom: 1rem;
    left: 1rem;
    right: 1rem;
    transform: translateY(100px);
  }
  
  .toast.show {
    transform: translateY(0);
  }
}

/* PWA Support Styles */
@media (display-mode: standalone) {
  body {
    padding-top: env(safe-area-inset-top);
    padding-bottom: env(safe-area-inset-bottom);
    padding-left: env(safe-area-inset-left);
    padding-right: env(safe-area-inset-right);
  }
}

/* Swipe indicator for password field */
.password-field::after {
  content: '';
  position: absolute;
  right: 4rem;
  top: 50%;
  transform: translateY(-50%);
  width: 2px;
  height: 60%;
  background: linear-gradient(to bottom, transparent, var(--primary-color), transparent);
  opacity: 0;
  transition: opacity var(--transition-normal);
  pointer-events: none;
}

.password-container:hover .password-field::after {
  opacity: 0.3;
}

/* Additional accessibility improvements */
@media (prefers-reduced-motion: reduce) {
  .touch-active {
    transform: none !important;
    transition: opacity 0.01ms !important;
  }
}