/**
 * Miles Value Finder - Design System
 *
 * This file provides a single source of truth for all design tokens.
 * Include this file in all HTML pages for consistent styling.
 *
 * Usage:
 *   <link rel="stylesheet" href="/css/design-system.css">
 *
 * Version: 1.0.0
 * Last Updated: January 2026
 */

/* ==========================================================================
   CSS Custom Properties (Design Tokens)
   ========================================================================== */

:root {
  /* Primary Colors - Blue */
  --primary-50: #e6f0ff;
  --primary-100: #cce0ff;
  --primary-200: #99c2ff;
  --primary-300: #66a3ff;
  --primary-400: #3385ff;
  --primary-500: #0066ff;
  --primary-600: #0052cc;
  --primary-700: #003d99;
  --primary-800: #002966;
  --primary-900: #001433;

  /* Secondary Colors - Yellow/Gold */
  --secondary-50: #fffbeb;
  --secondary-100: #fef3c7;
  --secondary-200: #fde68a;
  --secondary-300: #fcd34d;
  --secondary-400: #ffc933;
  --secondary-500: #ffbb00;
  --secondary-600: #d97706;
  --secondary-700: #b45309;
  --secondary-800: #92400e;
  --secondary-900: #78350f;

  /* Success Colors - Green */
  --success-50: #f0fdf4;
  --success-100: #dcfce7;
  --success-200: #bbf7d0;
  --success-300: #86efac;
  --success-400: #4ade80;
  --success-500: #22c55e;
  --success-600: #16a34a;
  --success-700: #15803d;
  --success-800: #166534;
  --success-900: #14532d;

  /* Warning Colors - Amber */
  --warning-50: #fffbeb;
  --warning-100: #fef3c7;
  --warning-200: #fde68a;
  --warning-300: #fcd34d;
  --warning-400: #fbbf24;
  --warning-500: #f59e0b;
  --warning-600: #d97706;
  --warning-700: #b45309;
  --warning-800: #92400e;
  --warning-900: #78350f;

  /* Error/Danger Colors - Red */
  --error-50: #fef2f2;
  --error-100: #fee2e2;
  --error-200: #fecaca;
  --error-300: #fca5a5;
  --error-400: #f87171;
  --error-500: #ef4444;
  --error-600: #dc2626;
  --error-700: #b91c1c;
  --error-800: #991b1b;
  --error-900: #7f1d1d;

  /* Gray Scale - Slate */
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  --gray-950: #020617;

  /* Shadows */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);

  /* Legacy shadow names for backward compatibility */
  --shadow-card: var(--shadow-md);
  --shadow-card-hover: var(--shadow-lg);

  /* Spacing Scale */
  --spacing-0: 0;
  --spacing-1: 0.25rem;   /* 4px */
  --spacing-2: 0.5rem;    /* 8px */
  --spacing-3: 0.75rem;   /* 12px */
  --spacing-4: 1rem;      /* 16px */
  --spacing-5: 1.25rem;   /* 20px */
  --spacing-6: 1.5rem;    /* 24px */
  --spacing-8: 2rem;      /* 32px */
  --spacing-10: 2.5rem;   /* 40px */
  --spacing-12: 3rem;     /* 48px */
  --spacing-16: 4rem;     /* 64px */
  --spacing-20: 5rem;     /* 80px */
  --spacing-24: 6rem;     /* 96px */

  /* Typography */
  --font-family-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-family-mono: ui-monospace, SFMono-Regular, 'SF Mono', Menlo, Consolas, 'Liberation Mono', monospace;

  /* Font Sizes */
  --text-xs: 0.75rem;     /* 12px */
  --text-sm: 0.875rem;    /* 14px */
  --text-base: 1rem;      /* 16px */
  --text-lg: 1.125rem;    /* 18px */
  --text-xl: 1.25rem;     /* 20px */
  --text-2xl: 1.5rem;     /* 24px */
  --text-3xl: 1.875rem;   /* 30px */
  --text-4xl: 2.25rem;    /* 36px */
  --text-5xl: 3rem;       /* 48px */

  /* Font Weights */
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  /* Line Heights */
  --leading-none: 1;
  --leading-tight: 1.25;
  --leading-snug: 1.375;
  --leading-normal: 1.5;
  --leading-relaxed: 1.625;
  --leading-loose: 2;

  /* Border Radius */
  --radius-none: 0;
  --radius-sm: 0.125rem;  /* 2px */
  --radius-md: 0.375rem;  /* 6px */
  --radius-lg: 0.5rem;    /* 8px */
  --radius-xl: 0.75rem;   /* 12px */
  --radius-2xl: 1rem;     /* 16px */
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 200ms ease;
  --transition-slow: 300ms ease;

  /* 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 Reset & Defaults
   ========================================================================== */

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

* {
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--gray-800);
  background-color: white;
}

/* ==========================================================================
   Utility Classes
   ========================================================================== */

/* Visually hidden but accessible to screen readers */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Hidden */
.hidden {
  display: none !important;
}

/* ==========================================================================
   Common Component Styles
   ========================================================================== */

/* Buttons - Base */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-2);
  padding: var(--spacing-3) var(--spacing-4);
  font-family: var(--font-family-sans);
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  line-height: var(--leading-tight);
  text-decoration: none;
  border: none;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-normal);
}

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

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

/* Button Variants */
.btn-primary {
  background: linear-gradient(135deg, var(--primary-500), var(--primary-600));
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover:not(:disabled) {
  background: linear-gradient(135deg, var(--primary-600), var(--primary-700));
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--gray-100);
  color: var(--gray-700);
  border: 1px solid var(--gray-300);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--gray-200);
  border-color: var(--gray-400);
}

.btn-ghost {
  background: transparent;
  color: var(--gray-600);
}

.btn-ghost:hover:not(:disabled) {
  background: var(--gray-100);
  color: var(--gray-900);
}

/* Form Inputs */
.form-input {
  width: 100%;
  padding: var(--spacing-3) var(--spacing-4);
  font-family: var(--font-family-sans);
  font-size: var(--text-base);
  color: var(--gray-900);
  background: white;
  border: 2px solid var(--gray-300);
  border-radius: var(--radius-lg);
  transition: all var(--transition-normal);
}

.form-input:focus {
  outline: none;
  border-color: var(--primary-500);
  box-shadow: 0 0 0 3px rgba(0, 102, 255, 0.1);
}

.form-input::placeholder {
  color: var(--gray-400);
}

.form-input:disabled {
  background: var(--gray-100);
  color: var(--gray-500);
  cursor: not-allowed;
}

/* Form Label */
.form-label {
  display: block;
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--gray-700);
  margin-bottom: var(--spacing-2);
}

/* Cards */
.card {
  background: white;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  padding: var(--spacing-6);
}

.card-hover {
  transition: all var(--transition-normal);
}

.card-hover:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

/* Alerts */
.alert {
  padding: var(--spacing-3) var(--spacing-4);
  border-radius: var(--radius-lg);
  font-size: var(--text-sm);
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
}

.alert-success {
  background: var(--success-50);
  color: var(--success-800);
  border: 1px solid var(--success-200);
}

.alert-error {
  background: var(--error-50);
  color: var(--error-800);
  border: 1px solid var(--error-200);
}

.alert-warning {
  background: var(--warning-50);
  color: var(--warning-800);
  border: 1px solid var(--warning-200);
}

.alert-info {
  background: var(--primary-50);
  color: var(--primary-800);
  border: 1px solid var(--primary-200);
}

/* Loading Spinner */
.spinner {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 2px solid var(--gray-200);
  border-radius: 50%;
  border-top-color: var(--primary-500);
  animation: spin 0.8s linear infinite;
}

.spinner-sm {
  width: 16px;
  height: 16px;
  border-width: 2px;
}

.spinner-lg {
  width: 32px;
  height: 32px;
  border-width: 3px;
}

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

/* Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

@media (min-width: 640px) {
  .container {
    padding: 0 var(--spacing-6);
  }
}

@media (min-width: 1024px) {
  .container {
    padding: 0 var(--spacing-8);
  }
}