/* ==========================================================================
   EC2 Pricing Dashboard - Main Stylesheet
   Mobile-first responsive design with accessibility features
   ========================================================================== */

/* CSS Custom Properties (Variables) */
:root {
  /* Colors */
  --color-primary: #0066cc;
  --color-primary-dark: #004499;
  --color-primary-light: #3385d6;
  --color-secondary: #6c757d;
  --color-success: #28a745;
  --color-warning: #ffc107;
  --color-danger: #dc3545;
  --color-info: #17a2b8;
  
  /* Neutral Colors */
  --color-white: #ffffff;
  --color-gray-50: #f8f9fa;
  --color-gray-100: #e9ecef;
  --color-gray-200: #dee2e6;
  --color-gray-300: #ced4da;
  --color-gray-400: #adb5bd;
  --color-gray-500: #6c757d;
  --color-gray-600: #495057;
  --color-gray-700: #343a40;
  --color-gray-800: #212529;
  --color-gray-900: #000000;
  
  /* Typography */
  --font-family-base: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;    /* 20px */
  --font-size-2xl: 1.5rem;    /* 24px */
  --font-size-3xl: 1.875rem;  /* 30px */
  --font-size-4xl: 2.25rem;   /* 36px */
  
  --font-weight-light: 300;
  --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;
  
  /* Spacing */
  --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 */
  
  /* Layout */
  --container-max-width: 1200px;
  --border-radius-sm: 0.25rem;
  --border-radius-md: 0.375rem;
  --border-radius-lg: 0.5rem;
  --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-fast: 150ms ease-in-out;
  --transition-normal: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
  
  /* Z-index scale */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal: 1040;
  --z-popover: 1050;
  --z-tooltip: 1060;
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
  :root {
    --color-white: #1a1a1a;
    --color-gray-50: #2d2d2d;
    --color-gray-100: #404040;
    --color-gray-200: #525252;
    --color-gray-300: #737373;
    --color-gray-400: #a3a3a3;
    --color-gray-500: #d4d4d4;
    --color-gray-600: #e5e5e5;
    --color-gray-700: #f5f5f5;
    --color-gray-800: #fafafa;
    --color-gray-900: #ffffff;
  }
}

/* ==========================================================================
   Base Styles
   ========================================================================== */

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

/* Remove default margins */
* {
  margin: 0;
}

/* HTML and Body */
html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family-base);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--color-gray-800);
  background-color: var(--color-gray-50);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Improve text rendering */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
  color: var(--color-gray-900);
}

/* Links */
a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover,
a:focus {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

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

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

/* Skip link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--color-gray-900);
  color: var(--color-white);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius-md);
  text-decoration: none;
  z-index: var(--z-tooltip);
  transition: top var(--transition-fast);
}

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

/* ==========================================================================
   Layout Components
   ========================================================================== */

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

@media (min-width: 768px) {
  .container {
    padding: 0 var(--spacing-lg);
  }
}

/* ==========================================================================
   Header
   ========================================================================== */

.header {
  background-color: var(--color-white);
  border-bottom: var(--border-width) solid var(--color-gray-200);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
}

.header__content {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  padding: var(--spacing-md) 0;
}

@media (min-width: 768px) {
  .header__content {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

.header__brand {
  text-align: center;
}

@media (min-width: 768px) {
  .header__brand {
    text-align: left;
  }
}

.header__title {
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-gray-900);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
}

@media (min-width: 768px) {
  .header__title {
    justify-content: flex-start;
    font-size: var(--font-size-3xl);
  }
}

.header__icon {
  font-size: var(--font-size-3xl);
}

.header__subtitle {
  font-size: var(--font-size-sm);
  color: var(--color-gray-600);
  margin-top: var(--spacing-xs);
}

/* Navigation */
.header__nav {
  display: flex;
  justify-content: center;
}

@media (min-width: 768px) {
  .header__nav {
    justify-content: flex-end;
  }
}

.nav-list {
  display: flex;
  list-style: none;
  padding: 0;
  gap: var(--spacing-lg);
}

.nav-list__link {
  font-weight: var(--font-weight-medium);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius-md);
  transition: all var(--transition-fast);
}

.nav-list__link:hover,
.nav-list__link:focus {
  background-color: var(--color-gray-100);
  text-decoration: none;
}

.nav-list__link--active {
  background-color: var(--color-primary);
  color: var(--color-white);
}

.nav-list__link--active:hover,
.nav-list__link--active:focus {
  background-color: var(--color-primary-dark);
  color: var(--color-white);
}

/* ==========================================================================
   Main Content
   ========================================================================== */

.main {
  min-height: calc(100vh - 200px);
  padding: var(--spacing-xl) 0;
}

/* ==========================================================================
   Loading and Error States
   ========================================================================== */

.loading-state,
.error-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--spacing-3xl) var(--spacing-md);
  min-height: 400px;
}

.loading-state__spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--color-gray-200);
  border-top: 4px solid var(--color-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: var(--spacing-lg);
}

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

.loading-state__text {
  font-size: var(--font-size-lg);
  color: var(--color-gray-600);
}

.error-state__icon {
  font-size: var(--font-size-4xl);
  margin-bottom: var(--spacing-md);
}

.error-state__title {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-md);
  color: var(--color-danger);
}

.error-state__message {
  font-size: var(--font-size-lg);
  color: var(--color-gray-600);
  margin-bottom: var(--spacing-xl);
  max-width: 500px;
}

/* ==========================================================================
   Dashboard Sections
   ========================================================================== */

.dashboard > * + * {
  margin-top: var(--spacing-3xl);
}

/* Section headings */
.summary__heading,
.filters__heading,
.charts__heading,
.data-table__heading {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-xl);
  color: var(--color-gray-900);
}

/* ==========================================================================
   Summary Cards
   ========================================================================== */

.summary__grid {
  display: grid;
  gap: var(--spacing-lg);
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .summary__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .summary__grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.summary-card {
  background-color: var(--color-white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-md);
  border: var(--border-width) solid var(--color-gray-200);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

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

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

.summary-card__title {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-gray-600);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.summary-card__icon {
  font-size: var(--font-size-xl);
  opacity: 0.7;
}

.summary-card__value {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-gray-900);
  margin-bottom: var(--spacing-xs);
}

.summary-card__label {
  font-size: var(--font-size-sm);
  color: var(--color-gray-500);
}

/* ==========================================================================
   Metadata Information
   ========================================================================== */

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

.metadata__grid {
  display: grid;
  gap: var(--spacing-md);
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .metadata__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.info-card {
  background-color: var(--color-gray-50);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-md);
  border: var(--border-width) solid var(--color-gray-200);
}

.info-card__content {
  display: flex;
  align-items: center;
  justify-content: center;
}

.status {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
}

.status__indicator {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--color-success);
}

.status--data-freshness .status__indicator {
  background-color: var(--color-success);
}

.status--data-stale .status__indicator {
  background-color: var(--color-warning);
}

.status--data-error .status__indicator {
  background-color: var(--color-danger);
}

.total-instances-count {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  color: var(--color-gray-700);
  margin: 0;
}

/* Screen reader only content */
.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;
}

/* ==========================================================================
   Filters
   ========================================================================== */

.filters {
  background-color: var(--color-white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-md);
  border: var(--border-width) solid var(--color-gray-200);
}

.filters__grid {
  display: grid;
  gap: var(--spacing-lg);
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .filters__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .filters__grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.filter-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.filter-group--actions {
  display: flex;
  flex-direction: row;
  align-items: end;
  gap: var(--spacing-md);
}

@media (min-width: 1024px) {
  .filter-group--actions {
    grid-column: span 3;
    justify-content: flex-end;
  }
}

.filter-group__label {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-gray-700);
}

.filter-group__select {
  padding: var(--spacing-sm) var(--spacing-md);
  border: var(--border-width) solid var(--color-gray-300);
  border-radius: var(--border-radius-md);
  font-size: var(--font-size-base);
  background-color: var(--color-white);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.filter-group__select:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.1);
}

.filter-group__help {
  font-size: var(--font-size-xs);
  color: var(--color-gray-500);
}

/* ==========================================================================
   Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  line-height: 1.5;
  border: var(--border-width) solid transparent;
  border-radius: var(--border-radius-md);
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

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

.btn--primary:hover:not(:disabled),
.btn--primary:focus:not(:disabled) {
  background-color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  text-decoration: none;
}

.btn--secondary {
  background-color: var(--color-gray-500);
  color: var(--color-white);
  border-color: var(--color-gray-500);
}

.btn--secondary:hover:not(:disabled),
.btn--secondary:focus:not(:disabled) {
  background-color: var(--color-gray-600);
  border-color: var(--color-gray-600);
  text-decoration: none;
}

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

.btn--outline:hover:not(:disabled),
.btn--outline:focus:not(:disabled) {
  background-color: var(--color-primary);
  color: var(--color-white);
  text-decoration: none;
}

/* ==========================================================================
   Charts
   ========================================================================== */

.charts__container {
  display: grid;
  gap: var(--spacing-xl);
  grid-template-columns: 1fr;
}

@media (min-width: 1024px) {
  .charts__container {
    grid-template-columns: repeat(2, 1fr);
  }
}

.chart-container {
  background-color: var(--color-white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-md);
  border: var(--border-width) solid var(--color-gray-200);
}

.chart-container__title {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--spacing-lg);
  color: var(--color-gray-900);
}

.chart-container__wrapper {
  position: relative;
  height: 300px;
  margin-bottom: var(--spacing-md);
}

.chart-container__canvas {
  max-width: 100%;
  height: auto;
}

.chart-container__description {
  font-size: var(--font-size-sm);
  color: var(--color-gray-600);
  text-align: center;
}

/* ==========================================================================
   Data Table
   ========================================================================== */

.data-table {
  background-color: var(--color-white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-md);
  border: var(--border-width) solid var(--color-gray-200);
}

.data-table__header {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}

@media (min-width: 768px) {
  .data-table__header {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

.data-table__actions {
  display: flex;
  gap: var(--spacing-md);
}

.table-container {
  overflow-x: auto;
  margin-bottom: var(--spacing-lg);
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--font-size-sm);
}

.table__header {
  background-color: var(--color-gray-50);
  padding: var(--spacing-md);
  text-align: left;
  font-weight: var(--font-weight-semibold);
  color: var(--color-gray-700);
  border-bottom: var(--border-width) solid var(--color-gray-200);
  white-space: nowrap;
}

.table__header--sortable {
  padding: 0;
}

.table__sort-btn {
  width: 100%;
  padding: var(--spacing-md);
  background: none;
  border: none;
  text-align: left;
  font-weight: var(--font-weight-semibold);
  color: var(--color-gray-700);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: background-color var(--transition-fast);
}

.table__sort-btn:hover,
.table__sort-btn:focus {
  background-color: var(--color-gray-100);
}

.table__sort-icon::after {
  content: '↕️';
  font-size: var(--font-size-xs);
  opacity: 0.5;
}

.table__sort-btn[aria-sort="ascending"] .table__sort-icon::after {
  content: '↑';
  opacity: 1;
}

.table__sort-btn[aria-sort="descending"] .table__sort-icon::after {
  content: '↓';
  opacity: 1;
}

.table td {
  padding: var(--spacing-md);
  border-bottom: var(--border-width) solid var(--color-gray-100);
  vertical-align: top;
}

.table tr:hover {
  background-color: var(--color-gray-50);
}

/* ==========================================================================
   Pagination
   ========================================================================== */

.pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-lg);
}

.pagination__btn {
  padding: var(--spacing-sm) var(--spacing-md);
  background-color: var(--color-white);
  border: var(--border-width) solid var(--color-gray-300);
  border-radius: var(--border-radius-md);
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.pagination__btn:hover:not(:disabled),
.pagination__btn:focus:not(:disabled) {
  background-color: var(--color-gray-50);
  border-color: var(--color-gray-400);
}

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

.pagination__info {
  font-size: var(--font-size-sm);
  color: var(--color-gray-600);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.footer {
  background-color: var(--color-gray-100);
  border-top: var(--border-width) solid var(--color-gray-200);
  padding: var(--spacing-xl) 0;
  margin-top: var(--spacing-3xl);
}

.footer__content {
  text-align: center;
}

.footer__text,
.footer__disclaimer {
  font-size: var(--font-size-sm);
  color: var(--color-gray-600);
  margin-bottom: var(--spacing-sm);
}

.footer__disclaimer {
  margin-bottom: 0;
}

.footer__link {
  color: var(--color-primary);
  font-weight: var(--font-weight-medium);
}

/* ==========================================================================
   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;
}

[hidden] {
  display: none !important;
}

.text-warning {
  color: var(--color-warning) !important;
}

/* ==========================================================================
   Print Styles
   ========================================================================== */

@media print {
  .header__nav,
  .filters,
  .charts,
  .data-table__actions,
  .pagination,
  .footer {
    display: none;
  }
  
  .summary-card,
  .data-table {
    box-shadow: none;
    border: var(--border-width) solid var(--color-gray-300);
  }
  
  .table {
    font-size: var(--font-size-xs);
  }
}

/* ==========================================================================
   Reduced Motion
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  
  .loading-state__spinner {
    animation: none;
    border-top-color: var(--color-gray-400);
  }
}

/* Footer Styles */
.footer {
  background: #2c3e50;
  color: #ecf0f1;
  padding: 2rem 0;
  margin-top: 4rem;
  border-top: 3px solid #3498db;
}

.footer__content {
  text-align: center;
}

.footer__text {
  font-size: 1rem;
  margin-bottom: 0.5rem;
  color: #ecf0f1;
}

.footer__contact {
  font-size: 0.9rem;
  margin-bottom: 0.5rem;
  color: #bdc3c7;
}

.footer__link {
  color: #3498db;
  text-decoration: none;
  transition: color 0.2s;
}

.footer__link:hover {
  color: #5dade2;
  text-decoration: underline;
}

.footer__copyright {
  font-size: 0.85rem;
  color: #95a5a6;
  margin-top: 0.5rem;
}

@media (max-width: 768px) {
  .footer {
    padding: 1.5rem 0;
    margin-top: 2rem;
  }
  
  .footer__text,
  .footer__contact {
    font-size: 0.85rem;
  }
  
  .footer__copyright {
    font-size: 0.75rem;
  }
}