/* 
 * WCAG 2.2 Level AA Compliant Reader CSS
 * Accessibility Features:
 * - High contrast support
 * - Focus indicators
 * - Screen reader friendly
 * - Keyboard navigation
 * - Reduced motion support
 * - Color contrast ratios >= 4.5:1
 */

/* CSS Custom Properties for Accessibility */
:root {
  /* Color Palette - WCAG AA Compliant */
  --color-primary: #0056b3;           /* 4.5:1 contrast on white */
  --color-primary-dark: #003d82;      /* High contrast variant */
  --color-secondary: #6c757d;         /* 4.5:1 contrast on white */
  --color-success: #155724;           /* 4.5:1 contrast on white */
  --color-warning: #856404;           /* 4.5:1 contrast on white */
  --color-error: #721c24;             /* 4.5:1 contrast on white */
  --color-info: #0c5460;              /* 4.5:1 contrast on white */
  
  /* Background Colors */
  --color-bg-primary: #ffffff;
  --color-bg-secondary: #f8f9fa;
  --color-bg-tertiary: #e9ecef;
  --color-bg-dark: #212529;
  
  /* Text Colors */
  --color-text-primary: #212529;      /* 16:1 contrast on white */
  --color-text-secondary: #495057;    /* 9:1 contrast on white */
  --color-text-muted: #6c757d;        /* 4.5:1 contrast on white */
  --color-text-inverse: #ffffff;
  
  /* Border Colors */
  --color-border-light: #dee2e6;
  --color-border-medium: #adb5bd;
  --color-border-dark: #495057;
  
  /* Focus and Interaction */
  --color-focus: #0066cc;
  --color-focus-shadow: rgba(0, 102, 204, 0.25);
  --color-hover: #e9ecef;
  --color-active: #dee2e6;
  
  /* High Contrast Mode Colors */
  --color-hc-bg: #000000;
  --color-hc-text: #ffffff;
  --color-hc-link: #ffff00;
  --color-hc-border: #ffffff;
  
  /* Spacing (based on 8px grid for consistency) */
  --spacing-xs: 0.25rem;   /* 4px */
  --spacing-sm: 0.5rem;    /* 8px */
  --spacing-md: 1rem;      /* 16px */
  --spacing-lg: 1.5rem;    /* 24px */
  --spacing-xl: 2rem;      /* 32px */
  --spacing-xxl: 3rem;     /* 48px */
  
  /* Typography */
  --font-family-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-family-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
  
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px - Base font size */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;    /* 20px */
  --font-size-xxl: 1.5rem;    /* 24px */
  --font-size-xxxl: 2rem;     /* 32px */
  
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* Layout */
  --header-height: 4rem;
  --sidebar-width: 320px;
  --toolbar-height: 3.5rem;
  
  /* Z-index layers */
  --z-base: 1;
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
  
  /* Transitions */
  --transition-fast: 0.15s ease-in-out;
  --transition-normal: 0.3s ease-in-out;
  --transition-slow: 0.5s ease-in-out;
  
  /* Border radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
  :root {
    --color-bg-primary: var(--color-hc-bg);
    --color-bg-secondary: var(--color-hc-bg);
    --color-bg-tertiary: var(--color-hc-bg);
    --color-text-primary: var(--color-hc-text);
    --color-text-secondary: var(--color-hc-text);
    --color-text-muted: var(--color-hc-text);
    --color-primary: var(--color-hc-link);
    --color-border-light: var(--color-hc-border);
    --color-border-medium: var(--color-hc-border);
    --color-border-dark: var(--color-hc-border);
  }
}

/* Reduced Motion Support */
@media (prefers-reduced-motion: reduce) {
  :root {
    --transition-fast: 0s;
    --transition-normal: 0s;
    --transition-slow: 0s;
  }
  
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Base Styles */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 16px; /* Explicit base font size for rem calculations */
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family-primary);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  min-height: 100vh;
  overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--spacing-md) 0;
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
  color: var(--color-text-primary);
}

h1 {
  font-size: var(--font-size-xxxl);
}

h2 {
  font-size: var(--font-size-xxl);
}

h3 {
  font-size: var(--font-size-xl);
}

h4 {
  font-size: var(--font-size-lg);
}

h5 {
  font-size: var(--font-size-base);
}

h6 {
  font-size: var(--font-size-sm);
}

p {
  margin: 0 0 var(--spacing-md) 0;
  color: var(--color-text-primary);
}

/* Links */
a {
  color: var(--color-primary);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
  text-decoration-thickness: 2px;
}

a:focus {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

a:focus:not(:focus-visible) {
  outline: none;
}

a:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

/* Skip Link for Screen Readers */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--color-primary);
  color: var(--color-text-inverse);
  padding: var(--spacing-sm) var(--spacing-md);
  text-decoration: none;
  border-radius: var(--radius-sm);
  z-index: var(--z-tooltip);
  font-weight: var(--font-weight-medium);
}

.skip-link:focus {
  top: 6px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  font-family: inherit;
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  line-height: 1.5;
  text-decoration: none;
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  min-height: 44px; /* WCAG touch target minimum */
  min-width: 44px;
  position: relative;
}

.btn:focus {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  box-shadow: 0 0 0 4px var(--color-focus-shadow);
}

.btn:focus:not(:focus-visible) {
  outline: none;
  box-shadow: none;
}

.btn:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  box-shadow: 0 0 0 4px var(--color-focus-shadow);
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  pointer-events: none;
}

/* Button Variants */
.btn-primary {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-text-inverse);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
}

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

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

.btn-outline:hover:not(:disabled) {
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
}

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

.btn-ghost:hover:not(:disabled) {
  background-color: var(--color-hover);
}

/* Button Sizes */
.btn-sm {
  padding: var(--spacing-xs) var(--spacing-sm);
  font-size: var(--font-size-sm);
  min-height: 32px;
  min-width: 32px;
}

.btn-lg {
  padding: var(--spacing-md) var(--spacing-lg);
  font-size: var(--font-size-lg);
  min-height: 48px;
  min-width: 48px;
}

/* Icon buttons */
.btn-icon {
  width: 44px;
  height: 44px;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.btn-icon-sm {
  width: 32px;
  height: 32px;
}

.btn-icon-lg {
  width: 48px;
  height: 48px;
}

/* Form Controls */
.form-control {
  display: block;
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  font-family: inherit;
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  border: 2px solid var(--color-border-medium);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  min-height: 44px; /* Touch target minimum */
}

.form-control:focus {
  outline: none;
  border-color: var(--color-focus);
  box-shadow: 0 0 0 4px var(--color-focus-shadow);
}

.form-control:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  background-color: var(--color-bg-tertiary);
}

.form-control::placeholder {
  color: var(--color-text-muted);
  opacity: 1;
}

/* Form Labels */
.form-label {
  display: block;
  margin-bottom: var(--spacing-xs);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
  font-size: var(--font-size-base);
}

.form-label.required::after {
  content: " *";
  color: var(--color-error);
}

/* Screen Reader Only Content */
.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

.sr-only-focusable:focus,
.sr-only-focusable:active {
  position: static !important;
  width: auto !important;
  height: auto !important;
  padding: inherit !important;
  margin: inherit !important;
  overflow: visible !important;
  clip: auto !important;
  white-space: inherit !important;
}

/* Loading States */
.loading {
  position: relative;
  pointer-events: none;
}

.loading::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 20px;
  height: 20px;
  margin: -10px 0 0 -10px;
  border: 2px solid var(--color-border-light);
  border-radius: 50%;
  border-top-color: var(--color-primary);
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

@media (prefers-reduced-motion: reduce) {
  .loading::after {
    animation: none;
    content: "Loading...";
    border: none;
    background: none;
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    width: auto;
    height: auto;
    margin: 0;
    top: auto;
    left: auto;
    position: static;
  }
}

/* Alert/Notification Styles */
.alert {
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-md);
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  position: relative;
}

.alert-success {
  background-color: #d4edda;
  border-color: var(--color-success);
  color: var(--color-success);
}

.alert-warning {
  background-color: #fff3cd;
  border-color: var(--color-warning);
  color: var(--color-warning);
}

.alert-error {
  background-color: #f8d7da;
  border-color: var(--color-error);
  color: var(--color-error);
}

.alert-info {
  background-color: #d1ecf1;
  border-color: var(--color-info);
  color: var(--color-info);
}

/* Tooltip Styles */
.tooltip {
  position: absolute;
  z-index: var(--z-tooltip);
  background: var(--color-text-primary);
  color: var(--color-text-inverse);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  white-space: nowrap;
  max-width: 200px;
  white-space: normal;
  word-wrap: break-word;
}

/* Focus Management */
.focus-trap {
  position: relative;
}

.focus-trap::before,
.focus-trap::after {
  content: "";
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
}

/* Responsive Design */
@media (max-width: 768px) {
  :root {
    --font-size-base: 1.125rem; /* 18px for better mobile readability */
    --spacing-md: 1.25rem;
    --spacing-lg: 2rem;
  }
  
  .btn {
    min-height: 48px; /* Larger touch targets on mobile */
    min-width: 48px;
  }
  
  .btn-icon {
    width: 48px;
    height: 48px;
  }
  
  .form-control {
    min-height: 48px;
  }
}

@media (max-width: 480px) {
  :root {
    --font-size-base: 1.25rem; /* 20px for small screens */
  }
}

/* Print Styles */
@media print {
  * {
    background: transparent !important;
    color: black !important;
    box-shadow: none !important;
  }
  
  a,
  a:visited {
    text-decoration: underline;
  }
  
  .btn,
  .no-print {
    display: none !important;
  }
  
  .print-only {
    display: block !important;
  }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg-primary: #1a1a1a;
    --color-bg-secondary: #2d2d2d;
    --color-bg-tertiary: #404040;
    --color-text-primary: #ffffff;
    --color-text-secondary: #e0e0e0;
    --color-text-muted: #a0a0a0;
    --color-border-light: #404040;
    --color-border-medium: #606060;
    --color-border-dark: #808080;
    --color-primary: #4da6ff;
    --color-primary-dark: #1a8cff;
  }
}

/* High contrast theme class for manual toggle */
.theme-high-contrast {
  --color-bg-primary: #000000;
  --color-bg-secondary: #000000;
  --color-bg-tertiary: #000000;
  --color-text-primary: #ffffff;
  --color-text-secondary: #ffffff;
  --color-text-muted: #ffffff;
  --color-primary: #ffff00;
  --color-primary-dark: #ffff66;
  --color-border-light: #ffffff;
  --color-border-medium: #ffffff;
  --color-border-dark: #ffffff;
  --color-focus: #00ff00;
}

/* Large text theme class */
.theme-large-text {
  --font-size-xs: 1rem;      /* 16px */
  --font-size-sm: 1.125rem;  /* 18px */
  --font-size-base: 1.25rem; /* 20px */
  --font-size-lg: 1.5rem;    /* 24px */
  --font-size-xl: 1.75rem;   /* 28px */
  --font-size-xxl: 2rem;     /* 32px */
  --font-size-xxxl: 2.5rem;  /* 40px */
}

/* Utility Classes */
.visually-hidden {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

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

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

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

.d-none {
  display: none !important;
}

.d-block {
  display: block !important;
}

.d-flex {
  display: flex !important;
}

.flex-column {
  flex-direction: column !important;
}

.align-items-center {
  align-items: center !important;
}

.justify-content-center {
  justify-content: center !important;
}

.justify-content-between {
  justify-content: space-between !important;
}

.w-100 {
  width: 100% !important;
}

.h-100 {
  height: 100% !important;
}

.m-0 {
  margin: 0 !important;
}

.mt-auto {
  margin-top: auto !important;
}

.mb-auto {
  margin-bottom: auto !important;
}

.p-0 {
  padding: 0 !important;
}

/* Animation classes */
.fade-in {
  animation: fadeIn 0.3s ease-in-out;
}

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

.slide-down {
  animation: slideDown 0.3s ease-in-out;
}

@keyframes slideDown {
  from {
    transform: translateY(-10px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

/* Ensure animations respect reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  .fade-in,
  .slide-down {
    animation: none;
  }
}