/**
 * AI Learning Portal v2 - Design System
 * Modern design system with Tailwind CSS utilities and custom components
 */

/* Import Tailwind CSS */
@import url('https://cdn.jsdelivr.net/npm/tailwindcss@3.4.0/base.css');
@import url('https://cdn.jsdelivr.net/npm/tailwindcss@3.4.0/components.css');
@import url('https://cdn.jsdelivr.net/npm/tailwindcss@3.4.0/utilities.css');

/* CSS Custom Properties for Design System */
:root {
  /* Colors - Primary Palette */
  --color-primary-50: #eff6ff;
  --color-primary-100: #dbeafe;
  --color-primary-200: #bfdbfe;
  --color-primary-300: #93c5fd;
  --color-primary-400: #60a5fa;
  --color-primary-500: #3b82f6;
  --color-primary-600: #2563eb;
  --color-primary-700: #1d4ed8;
  --color-primary-800: #1e40af;
  --color-primary-900: #1e3a8a;
  --color-primary-950: #172554;

  /* Colors - Secondary Palette */
  --color-secondary-50: #f8fafc;
  --color-secondary-100: #f1f5f9;
  --color-secondary-200: #e2e8f0;
  --color-secondary-300: #cbd5e1;
  --color-secondary-400: #94a3b8;
  --color-secondary-500: #64748b;
  --color-secondary-600: #475569;
  --color-secondary-700: #334155;
  --color-secondary-800: #1e293b;
  --color-secondary-900: #0f172a;

  /* Colors - Semantic */
  --color-success-50: #ecfdf5;
  --color-success-500: #10b981;
  --color-success-600: #059669;
  --color-success-700: #047857;

  --color-warning-50: #fffbeb;
  --color-warning-500: #f59e0b;
  --color-warning-600: #d97706;
  --color-warning-700: #b45309;

  --color-error-50: #fef2f2;
  --color-error-500: #ef4444;
  --color-error-600: #dc2626;
  --color-error-700: #b91c1c;

  --color-info-50: #eff6ff;
  --color-info-500: #3b82f6;
  --color-info-600: #2563eb;
  --color-info-700: #1d4ed8;

  /* Typography */
  --font-family-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-family-mono: 'SF Mono', Monaco, Inconsolata, 'Roboto Mono', monospace;

  /* Spacing Scale */
  --spacing-xs: 0.25rem;   /* 4px */
  --spacing-sm: 0.5rem;    /* 8px */
  --spacing-md: 1rem;      /* 16px */
  --spacing-lg: 1.5rem;    /* 24px */
  --spacing-xl: 2rem;      /* 32px */
  --spacing-2xl: 3rem;     /* 48px */
  --spacing-3xl: 4rem;     /* 64px */

  /* Border Radius */
  --radius-sm: 0.25rem;    /* 4px */
  --radius-md: 0.375rem;   /* 6px */
  --radius-lg: 0.5rem;     /* 8px */
  --radius-xl: 0.75rem;    /* 12px */
  --radius-2xl: 1rem;      /* 16px */
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

  /* Z-Index Scale */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
  --z-toast: 1080;
}

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

html {
  font-family: var(--font-family-sans);
  line-height: 1.6;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  padding: 0;
  background-color: var(--color-secondary-50);
  color: var(--color-secondary-900);
}

/* Focus Management for Accessibility */
*:focus {
  outline: 2px solid var(--color-primary-500);
  outline-offset: 2px;
}

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

*:focus-visible {
  outline: 2px solid var(--color-primary-500);
  outline-offset: 2px;
}

/* Skip Link for Screen Readers */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--color-primary-600);
  color: white;
  padding: 8px;
  text-decoration: none;
  border-radius: var(--radius-md);
  z-index: var(--z-tooltip);
  transition: top 0.3s;
}

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

/* Component Base Classes */

/* Button Component */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: 0.875rem;
  font-weight: 500;
  line-height: 1.25rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s ease-in-out;
  text-decoration: none;
  white-space: nowrap;
  user-select: none;
  position: relative;
  overflow: hidden;
}

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

.btn:focus {
  outline: 2px solid var(--color-primary-500);
  outline-offset: 2px;
}

/* Button Variants */
.btn-primary {
  background-color: var(--color-primary-600);
  color: white;
  border-color: var(--color-primary-600);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-primary-700);
  border-color: var(--color-primary-700);
}

.btn-secondary {
  background-color: white;
  color: var(--color-secondary-700);
  border-color: var(--color-secondary-300);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-secondary-50);
  border-color: var(--color-secondary-400);
}

.btn-success {
  background-color: var(--color-success-600);
  color: white;
  border-color: var(--color-success-600);
}

.btn-success:hover:not(:disabled) {
  background-color: var(--color-success-700);
  border-color: var(--color-success-700);
}

.btn-warning {
  background-color: var(--color-warning-600);
  color: white;
  border-color: var(--color-warning-600);
}

.btn-warning:hover:not(:disabled) {
  background-color: var(--color-warning-700);
  border-color: var(--color-warning-700);
}

.btn-error {
  background-color: var(--color-error-600);
  color: white;
  border-color: var(--color-error-600);
}

.btn-error:hover:not(:disabled) {
  background-color: var(--color-error-700);
  border-color: var(--color-error-700);
}

/* Button Sizes */
.btn-sm {
  padding: var(--spacing-xs) var(--spacing-sm);
  font-size: 0.75rem;
  line-height: 1rem;
}

.btn-lg {
  padding: var(--spacing-md) var(--spacing-lg);
  font-size: 1rem;
  line-height: 1.5rem;
}

.btn-xl {
  padding: var(--spacing-lg) var(--spacing-xl);
  font-size: 1.125rem;
  line-height: 1.75rem;
}

/* Card Component */
.card {
  background-color: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-secondary-200);
  overflow: hidden;
}

.card-header {
  padding: var(--spacing-lg);
  border-bottom: 1px solid var(--color-secondary-200);
  background-color: var(--color-secondary-50);
}

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

.card-footer {
  padding: var(--spacing-lg);
  border-top: 1px solid var(--color-secondary-200);
  background-color: var(--color-secondary-50);
}

/* Form Components */
.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-secondary-700);
  margin-bottom: var(--spacing-sm);
}

.form-label.required::after {
  content: ' *';
  color: var(--color-error-500);
}

.form-input {
  display: block;
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: 0.875rem;
  line-height: 1.25rem;
  color: var(--color-secondary-900);
  background-color: white;
  border: 1px solid var(--color-secondary-300);
  border-radius: var(--radius-md);
  transition: border-color 0.2s ease-in-out, box-shadow 0.2s ease-in-out;
}

.form-input:focus {
  outline: none;
  border-color: var(--color-primary-500);
  box-shadow: 0 0 0 3px rgb(59 130 246 / 0.1);
}

.form-input:disabled {
  background-color: var(--color-secondary-50);
  color: var(--color-secondary-500);
  cursor: not-allowed;
}

.form-input.error {
  border-color: var(--color-error-500);
}

.form-input.error:focus {
  border-color: var(--color-error-500);
  box-shadow: 0 0 0 3px rgb(239 68 68 / 0.1);
}

.form-error {
  margin-top: var(--spacing-xs);
  font-size: 0.75rem;
  color: var(--color-error-600);
}

.form-help {
  margin-top: var(--spacing-xs);
  font-size: 0.75rem;
  color: var(--color-secondary-500);
}

/* Alert Component */
.alert {
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  margin-bottom: var(--spacing-lg);
}

.alert-success {
  background-color: var(--color-success-50);
  border-color: var(--color-success-200);
  color: var(--color-success-800);
}

.alert-warning {
  background-color: var(--color-warning-50);
  border-color: var(--color-warning-200);
  color: var(--color-warning-800);
}

.alert-error {
  background-color: var(--color-error-50);
  border-color: var(--color-error-200);
  color: var(--color-error-800);
}

.alert-info {
  background-color: var(--color-info-50);
  border-color: var(--color-info-200);
  color: var(--color-info-800);
}

/* Modal Component */
.modal-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgb(0 0 0 / 0.5);
  z-index: var(--z-modal-backdrop);
  opacity: 0;
  transition: opacity 0.3s ease-in-out;
}

.modal-backdrop.show {
  opacity: 1;
}

.modal {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0.95);
  background-color: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  z-index: var(--z-modal);
  max-width: 90vw;
  max-height: 90vh;
  overflow: hidden;
  transition: transform 0.3s ease-in-out;
}

.modal.show {
  transform: translate(-50%, -50%) scale(1);
}

.modal-header {
  padding: var(--spacing-lg);
  border-bottom: 1px solid var(--color-secondary-200);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-secondary-900);
  margin: 0;
}

.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--color-secondary-400);
  cursor: pointer;
  padding: var(--spacing-xs);
  border-radius: var(--radius-sm);
  transition: color 0.2s ease-in-out;
}

.modal-close:hover {
  color: var(--color-secondary-600);
}

.modal-body {
  padding: var(--spacing-lg);
  overflow-y: auto;
}

.modal-footer {
  padding: var(--spacing-lg);
  border-top: 1px solid var(--color-secondary-200);
  display: flex;
  gap: var(--spacing-sm);
  justify-content: flex-end;
}

/* Loading Component */
.loading-spinner {
  display: inline-block;
  width: 1rem;
  height: 1rem;
  border: 2px solid var(--color-secondary-200);
  border-top: 2px solid var(--color-primary-600);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

.loading-spinner-lg {
  width: 2rem;
  height: 2rem;
  border-width: 3px;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

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

.text-truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.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;
}

/* Responsive Design Utilities */
@media (max-width: 640px) {
  .btn {
    width: 100%;
    justify-content: center;
  }
  
  .modal {
    margin: var(--spacing-md);
    max-width: calc(100vw - 2rem);
  }
  
  .card-header,
  .card-body,
  .card-footer {
    padding: var(--spacing-md);
  }
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
  :root {
    --color-primary-600: #0000ff;
    --color-secondary-300: #000000;
    --color-secondary-700: #000000;
  }
  
  .btn {
    border-width: 2px;
  }
}

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

/* Dark Mode Support (for future implementation) */
@media (prefers-color-scheme: dark) {
  :root {
    --color-secondary-50: #0f172a;
    --color-secondary-100: #1e293b;
    --color-secondary-900: #f8fafc;
  }
  
  body {
    background-color: var(--color-secondary-100);
    color: var(--color-secondary-900);
  }
  
  .card {
    background-color: var(--color-secondary-100);
    border-color: var(--color-secondary-700);
  }
}