/* ==========================================================================
   Design System & Tokens
   ========================================================================== */

:root {
  /* Colors - HSL for easy manipulation */
  --color-primary-h: 220;
  --color-primary-s: 70%;
  --color-primary-l: 50%;
  --color-primary: hsl(var(--color-primary-h), var(--color-primary-s), var(--color-primary-l));
  --color-primary-dark: hsl(var(--color-primary-h), var(--color-primary-s), 40%);
  --color-primary-light: hsl(var(--color-primary-h), var(--color-primary-s), 60%);
  
  --color-accent-h: 280;
  --color-accent-s: 60%;
  --color-accent-l: 55%;
  --color-accent: hsl(var(--color-accent-h), var(--color-accent-s), var(--color-accent-l));
  
  --color-success: hsl(140, 60%, 45%);
  --color-warning: hsl(40, 90%, 55%);
  --color-error: hsl(0, 70%, 55%);
  --color-info: hsl(200, 70%, 50%);
  
  /* Light theme */
  --bg-primary: hsl(0, 0%, 100%);
  --bg-secondary: hsl(220, 20%, 97%);
  --bg-tertiary: hsl(220, 20%, 94%);
  --bg-dark: hsl(220, 30%, 10%);
  
  --text-primary: hsl(220, 20%, 15%);
  --text-secondary: hsl(220, 15%, 45%);
  --text-tertiary: hsl(220, 10%, 60%);
  --text-inverse: hsl(0, 0%, 100%);
  
  --border-color: hsl(220, 15%, 88%);
  --border-color-hover: hsl(220, 20%, 75%);
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.08), 0 4px 6px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1), 0 10px 10px rgba(0, 0, 0, 0.04);
  
  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, monospace;
  
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  
  --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 */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  
  /* Border radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Z-index */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-toast: 1060;
  --z-tooltip: 1070;
  
  /* Grid */
  --grid-gap: var(--space-6);
  --container-max-width: 1280px;
}

/* Dark theme */
[data-theme="dark"] {
  --bg-primary: hsl(220, 25%, 10%);
  --bg-secondary: hsl(220, 25%, 13%);
  --bg-tertiary: hsl(220, 25%, 16%);
  --bg-dark: hsl(220, 30%, 8%);
  
  --text-primary: hsl(220, 20%, 95%);
  --text-secondary: hsl(220, 15%, 70%);
  --text-tertiary: hsl(220, 10%, 55%);
  --text-inverse: hsl(220, 20%, 15%);
  
  --border-color: hsl(220, 20%, 25%);
  --border-color-hover: hsl(220, 20%, 35%);
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4), 0 2px 4px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5), 0 4px 6px rgba(0, 0, 0, 0.3);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.6), 0 10px 10px rgba(0, 0, 0, 0.4);
}

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

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ==========================================================================
   Typography
   ========================================================================== */

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-4);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

p {
  margin-bottom: var(--space-4);
}

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

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

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

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background-color: var(--bg-tertiary);
  padding: 0.2em 0.4em;
  border-radius: var(--radius-sm);
}

.text-secondary {
  color: var(--text-secondary);
}

.text-tertiary {
  color: var(--text-tertiary);
}

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

.container {
  max-width: var(--container-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-6);
  padding-right: var(--space-6);
}

.section {
  padding-top: var(--space-20);
  padding-bottom: var(--space-20);
}

.section--dark {
  background-color: var(--bg-secondary);
}

.section__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-8);
  gap: var(--space-4);
  flex-wrap: wrap;
}

.section__title {
  font-size: var(--font-size-3xl);
  margin-bottom: 0;
}

.section__description {
  color: var(--text-secondary);
  max-width: 60ch;
  margin-bottom: var(--space-6);
}

.section__actions {
  display: flex;
  gap: var(--space-3);
}

/* Grid System */
.grid {
  display: grid;
  gap: var(--grid-gap);
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
}

.grid--2 {
  grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
}

@media (max-width: 768px) {
  .grid, .grid--2 {
    grid-template-columns: 1fr;
  }
}

/* ==========================================================================
   Navigation
   ========================================================================== */

.nav {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  backdrop-filter: blur(12px);
  background-color: rgba(255, 255, 255, 0.9);
}

[data-theme="dark"] .nav {
  background-color: rgba(28, 32, 41, 0.9);
}

.nav__container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: var(--space-4) var(--space-6);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-4);
}

.nav__logo {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  margin: 0;
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.nav__icon {
  color: var(--color-primary);
}

.nav__actions {
  display: flex;
  gap: var(--space-3);
  align-items: center;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */

.hero {
  position: relative;
  min-height: 600px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
}

.hero__bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.hero__pattern {
  width: 100%;
  height: 100%;
  color: var(--color-primary);
}

.hero__content {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 900px;
  padding: var(--space-12) var(--space-6);
}

.hero__title {
  font-size: var(--font-size-5xl);
  margin-bottom: var(--space-4);
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero__subtitle {
  font-size: var(--font-size-xl);
  color: var(--text-secondary);
  margin-bottom: var(--space-8);
}

.hero__cta {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  margin-bottom: var(--space-12);
  flex-wrap: wrap;
}

.hero__stats {
  display: flex;
  gap: var(--space-8);
  justify-content: center;
  flex-wrap: wrap;
}

.stat {
  text-align: center;
}

.stat__value {
  font-size: var(--font-size-4xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  line-height: 1;
  margin-bottom: var(--space-2);
}

.stat__label {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ==========================================================================
   Components - Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  line-height: 1;
  border: none;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

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

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

.btn--primary:hover {
  background-color: var(--color-primary-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn--secondary {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.btn--secondary:hover {
  background-color: var(--bg-secondary);
  border-color: var(--border-color-hover);
}

.btn--outline {
  background-color: transparent;
  color: var(--text-primary);
  border: 2px solid var(--border-color);
}

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

.btn--icon {
  padding: var(--space-2);
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background-color: transparent;
  color: var(--text-secondary);
}

.btn--icon:hover {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
}

.btn--small {
  padding: var(--space-2) var(--space-4);
  font-size: var(--font-size-sm);
}

.btn--large {
  padding: var(--space-4) var(--space-8);
  font-size: var(--font-size-lg);
}

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

/* ==========================================================================
   Components - Cards
   ========================================================================== */

.card {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-2xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-base);
}

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

.card h4 {
  margin-bottom: var(--space-4);
}

/* Species Card */
.species-card {
  cursor: pointer;
  position: relative;
}

.species-card__header {
  display: flex;
  justify-content: space-between;
  align-items: start;
  margin-bottom: var(--space-4);
}

.species-card__title {
  font-size: var(--font-size-xl);
  font-style: italic;
  margin-bottom: var(--space-1);
}

.species-card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.species-card__data {
  display: grid;
  gap: var(--space-3);
}

.species-card__stat {
  display: flex;
  justify-content: space-between;
  font-size: var(--font-size-sm);
}

.species-card__stat-label {
  color: var(--text-secondary);
}

.species-card__stat-value {
  font-weight: var(--font-weight-semibold);
  font-feature-settings: "tnum";
}

/* ==========================================================================
   Components - Chips & Badges
   ========================================================================== */

.chip {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-3);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  border-radius: var(--radius-full);
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.chip--period {
  background-color: hsl(200, 70%, 90%);
  color: hsl(200, 70%, 30%);
}

[data-theme="dark"] .chip--period {
  background-color: hsl(200, 70%, 20%);
  color: hsl(200, 70%, 80%);
}

.chip--diet-carnivore {
  background-color: hsl(0, 70%, 90%);
  color: hsl(0, 70%, 35%);
}

[data-theme="dark"] .chip--diet-carnivore {
  background-color: hsl(0, 70%, 20%);
  color: hsl(0, 70%, 80%);
}

.chip--diet-herbivore {
  background-color: hsl(140, 60%, 90%);
  color: hsl(140, 60%, 30%);
}

[data-theme="dark"] .chip--diet-herbivore {
  background-color: hsl(140, 60%, 20%);
  color: hsl(140, 60%, 80%);
}

.chip--clade {
  background-color: hsl(280, 50%, 90%);
  color: hsl(280, 50%, 35%);
}

[data-theme="dark"] .chip--clade {
  background-color: hsl(280, 50%, 20%);
  color: hsl(280, 50%, 80%);
}

.chip--removable {
  cursor: pointer;
  padding-right: var(--space-1);
}

.chip__remove {
  width: 16px;
  height: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background-color: rgba(0, 0, 0, 0.1);
  transition: background-color var(--transition-fast);
}

.chip__remove:hover {
  background-color: rgba(0, 0, 0, 0.2);
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

/* ==========================================================================
   Components - Forms
   ========================================================================== */

.search-box {
  position: relative;
  flex: 1;
  min-width: 250px;
}

.search-box__icon {
  position: absolute;
  left: var(--space-3);
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  pointer-events: none;
}

.search-box__input {
  width: 100%;
  padding: var(--space-3) var(--space-3) var(--space-3) var(--space-10);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
}

.search-box__input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px hsla(var(--color-primary-h), var(--color-primary-s), var(--color-primary-l), 0.1);
}

.filter-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.filter-label {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--text-secondary);
}

.filter-select {
  padding: var(--space-3) var(--space-4);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.filter-select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px hsla(var(--color-primary-h), var(--color-primary-s), var(--color-primary-l), 0.1);
}

.filters {
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
  align-items: end;
  margin-bottom: var(--space-6);
  padding: var(--space-6);
  background-color: var(--bg-secondary);
  border-radius: var(--radius-xl);
}

.results-info {
  margin-bottom: var(--space-4);
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

/* Slider */
.slider-control {
  margin: var(--space-6) 0;
}

.slider-control label {
  display: block;
  font-weight: var(--font-weight-medium);
  margin-bottom: var(--space-3);
}

.slider {
  width: 100%;
  height: 6px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  outline: none;
  -webkit-appearance: none;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.slider::-webkit-slider-thumb:hover {
  transform: scale(1.2);
  box-shadow: 0 0 0 6px hsla(var(--color-primary-h), var(--color-primary-s), var(--color-primary-l), 0.2);
}

.slider::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  border: none;
  transition: all var(--transition-fast);
}

.slider::-moz-range-thumb:hover {
  transform: scale(1.2);
}

.slider-labels {
  display: flex;
  justify-content: space-between;
  margin-top: var(--space-2);
  font-size: var(--font-size-xs);
  color: var(--text-secondary);
}

/* Multiselect */
.multiselect {
  margin-bottom: var(--space-4);
}

.multiselect label {
  display: block;
  font-weight: var(--font-weight-medium);
  margin-bottom: var(--space-2);
}

.multiselect__select {
  width: 100%;
  padding: var(--space-3);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
}

/* ==========================================================================
   Components - Tabs
   ========================================================================== */

.tabs {
  display: flex;
  gap: var(--space-1);
  border-bottom: 2px solid var(--border-color);
  margin-bottom: var(--space-6);
  overflow-x: auto;
}

.tab {
  padding: var(--space-3) var(--space-5);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.tab:hover {
  color: var(--text-primary);
  background-color: var(--bg-tertiary);
}

.tab--active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

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

.tab-panel {
  animation: fadeIn var(--transition-base);
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   Components - Modal
   ========================================================================== */

.modal {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
}

.modal__backdrop {
  position: absolute;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  animation: fadeIn var(--transition-base);
}

.modal__container {
  position: relative;
  background-color: var(--bg-primary);
  border-radius: var(--radius-2xl);
  box-shadow: var(--shadow-xl);
  max-width: 800px;
  max-height: 90vh;
  width: 100%;
  display: flex;
  flex-direction: column;
  animation: slideUp var(--transition-base);
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.modal__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-6);
  border-bottom: 1px solid var(--border-color);
}

.modal__title {
  margin: 0;
  font-size: var(--font-size-2xl);
}

.modal__content {
  padding: var(--space-6);
  overflow-y: auto;
  flex: 1;
}

.modal__footer {
  padding: var(--space-6);
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: flex-end;
  gap: var(--space-3);
}

/* ==========================================================================
   Components - Toast
   ========================================================================== */

.toast-container {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  max-width: 400px;
}

.toast {
  padding: var(--space-4) var(--space-5);
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  animation: slideInRight var(--transition-base);
}

@keyframes slideInRight {
  from { opacity: 0; transform: translateX(100%); }
  to { opacity: 1; transform: translateX(0); }
}

.toast--success {
  border-left-color: var(--color-success);
}

.toast--error {
  border-left-color: var(--color-error);
}

.toast--warning {
  border-left-color: var(--color-warning);
}

/* ==========================================================================
   Components - Timeline
   ========================================================================== */

.timeline {
  position: relative;
  height: 400px;
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  overflow: hidden;
  cursor: grab;
}

.timeline:active {
  cursor: grabbing;
}

.timeline-controls {
  display: flex;
  gap: var(--space-3);
  justify-content: center;
  margin-bottom: var(--space-4);
}

/* ==========================================================================
   Components - Charts
   ========================================================================== */

.chart {
  min-height: 300px;
  position: relative;
}

.chart svg {
  width: 100%;
  height: 100%;
}

/* ==========================================================================
   Components - Callouts
   ========================================================================== */

.callout {
  padding: var(--space-4);
  border-left: 4px solid var(--color-primary);
  background-color: var(--bg-secondary);
  border-radius: var(--radius-md);
  margin: var(--space-4) 0;
}

.callout--info {
  border-left-color: var(--color-info);
}

.callout--warning {
  border-left-color: var(--color-warning);
}

.callout--success {
  border-left-color: var(--color-success);
}

/* ==========================================================================
   Components - Formula Display
   ========================================================================== */

.formula {
  padding: var(--space-5);
  background-color: var(--bg-tertiary);
  border-radius: var(--radius-lg);
  margin: var(--space-4) 0;
  font-family: var(--font-mono);
}

.formula__title {
  font-family: var(--font-sans);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  margin-bottom: var(--space-3);
}

.formula code {
  display: block;
  font-size: var(--font-size-lg);
  background: none;
  padding: 0;
  margin: var(--space-2) 0;
}

.formula__expanded {
  margin-top: var(--space-3);
  padding-top: var(--space-3);
  border-top: 1px solid var(--border-color);
  color: var(--text-secondary);
}

/* ==========================================================================
   Components - Accordion
   ========================================================================== */

.accordion {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.accordion-item {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.accordion-header {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-4) var(--space-5);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  text-align: left;
  background-color: var(--bg-primary);
  border: none;
  cursor: pointer;
  transition: background-color var(--transition-fast);
}

.accordion-header:hover {
  background-color: var(--bg-secondary);
}

.accordion-header[aria-expanded="true"] .accordion-icon {
  transform: rotate(180deg);
}

.accordion-icon {
  transition: transform var(--transition-fast);
}

.accordion-content {
  padding: 0 var(--space-5) var(--space-4) var(--space-5);
}

/* ==========================================================================
   Components - Glossary
   ========================================================================== */

.glossary {
  display: grid;
  gap: var(--space-6);
}

.glossary-item {
  padding-bottom: var(--space-4);
  border-bottom: 1px solid var(--border-color);
}

.glossary-item:last-child {
  border-bottom: none;
}

.glossary-term {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--space-2);
}

.glossary-def {
  color: var(--text-secondary);
}

/* ==========================================================================
   Components - Comparison
   ========================================================================== */

.comparator-controls {
  display: flex;
  gap: var(--space-4);
  align-items: end;
  margin-bottom: var(--space-8);
  flex-wrap: wrap;
}

.comparison-grid {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.comparison-card {
  padding: var(--space-5);
  background-color: var(--bg-secondary);
  border-radius: var(--radius-xl);
}

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

.footer {
  background-color: var(--bg-dark);
  color: var(--text-inverse);
  padding: var(--space-16) 0 var(--space-8);
  margin-top: var(--space-24);
}

.footer__content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer__section h4 {
  margin-bottom: var(--space-4);
  color: var(--text-inverse);
}

.footer__links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.footer__links a {
  color: var(--text-secondary);
}

.footer__links a:hover {
  color: var(--text-inverse);
}

.footer__bottom {
  padding-top: var(--space-6);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  text-align: center;
  color: var(--text-secondary);
}

/* ==========================================================================
   Utilities
   ========================================================================== */

.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] {
  display: none !important;
}

/* ==========================================================================
   Responsive
   ========================================================================== */

@media (max-width: 768px) {
  .hero__title {
    font-size: var(--font-size-3xl);
  }
  
  .hero__cta {
    flex-direction: column;
    width: 100%;
  }
  
  .hero__cta .btn {
    width: 100%;
  }
  
  .filters {
    flex-direction: column;
    align-items: stretch;
  }
  
  .filter-group {
    width: 100%;
  }
  
  .section__header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .tabs {
    flex-wrap: wrap;
  }
  
  .modal__container {
    margin: var(--space-4);
    max-height: calc(100vh - var(--space-8));
  }
}

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

@media print {
  .nav, .hero__cta, .filters, .btn, .modal, .toast-container {
    display: none !important;
  }
  
  .card {
    page-break-inside: avoid;
  }
}