/*====================================================================*\
  ECNETICA APP - STYLESHEET
  Matches the style of the existing Jupyter Book frontend.
\*====================================================================*/

/* --- CSS Variables (from existing _static/style.css) --- */

:root {
  --background-primary: #ffffff;
  --background-secondary: #f8f9fa;
  --background-tertiary: #e9ecef;
  --primary: #3498db;
  --primary-hover: #2980b9;
  --primary-light: #d6eaf8;
  --secondary: #95a5a6;
  --secondary-hover: #7f8c8d;
  --text-primary: #2c3e50;
  --text-secondary: #6c757d;
  --text-muted: #adb5bd;
  --text-inverse: #ffffff;
  --success: #27ae60;
  --success-bg: #e8f8f5;
  --error: #c0392b;
  --error-bg: #fdedec;
  --warning: #f39c12;
  --warning-bg: #fef9e7;
  --info: #3498db;
  --info-bg: #e8f4fc;
  --border-primary: #dee2e6;
  --border-secondary: #999999;
  --border-light: #e9ecef;
  --shadow-light: 0 1px 3px rgba(0,0,0,0.1);
  --shadow-medium: 0 2px 10px rgba(0,0,0,0.1);
  --shadow-heavy: 0 4px 20px rgba(0,0,0,0.15);
  --spacing-xs: 5px;
  --spacing-sm: 10px;
  --spacing-md: 15px;
  --spacing-lg: 20px;
  --spacing-xl: 30px;
  --spacing-xxl: 40px;
  --border-radius-sm: 5px;
  --border-radius-md: 8px;
  --border-radius-lg: 10px;
  --category-scientific: #3498db;
  --category-engineering: #e67e22;
  --category-financial: #2ecc71;
  --category-creative: #9b59b6;
}

/* --- Base Reset & Typography --- */

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

body {
  margin: 0;
  font-family: Verdana, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--background-primary);
  color: var(--text-primary);
  line-height: 1.6;
}

h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  margin-top: 0;
}

h1, h2 {
  text-align: center;
}

p {
  text-align: justify;
}

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

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

/* --- Layout --- */

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

.site-main {
  min-height: calc(100vh - 140px);
}

/* --- Navigation --- */

.site-nav {
  background-color: var(--background-secondary);
  border-bottom: 1px solid var(--border-primary);
  padding: var(--spacing-md) var(--spacing-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: var(--shadow-light);
}

.nav-brand a {
  font-size: 1.4em;
  font-weight: bold;
  color: var(--primary);
  text-decoration: none;
  font-family: Cambria, Georgia, Times, serif;
}

.nav-links {
  display: flex;
  gap: var(--spacing-lg);
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95em;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius-sm);
  transition: all 0.2s ease;
}

.nav-links a:hover {
  color: var(--primary);
  background-color: var(--primary-light);
  text-decoration: none;
}

/* --- Footer --- */

.site-footer {
  background-color: var(--background-secondary);
  border-top: 1px solid var(--border-primary);
  padding: var(--spacing-lg);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9em;
}

/* --- Buttons --- */

.btn {
  display: inline-block;
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--border-radius-sm);
  font-size: 1em;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.2s ease;
  border: 2px solid transparent;
}

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

.btn-primary:hover {
  background-color: var(--primary-hover);
  color: var(--text-inverse);
  text-decoration: none;
}

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

.btn-secondary:hover {
  background-color: var(--secondary-hover);
  color: var(--text-inverse);
  text-decoration: none;
}

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

.btn-outline:hover {
  background-color: var(--primary);
  color: var(--text-inverse);
  text-decoration: none;
}

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

.btn-success:hover {
  background-color: #1e8449;
  color: var(--text-inverse);
  text-decoration: none;
}

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

.btn-danger:hover {
  background-color: #a93226;
  color: var(--text-inverse);
  text-decoration: none;
}

.btn-full {
  width: 100%;
  text-align: center;
}

/* --- Hero Section --- */

.hero {
  text-align: center;
  padding: var(--spacing-xxl) 0;
}

.hero h1 {
  font-size: 3em;
  font-family: Cambria, Georgia, Times, serif;
  color: var(--primary);
  margin-bottom: var(--spacing-sm);
}

.subtitle {
  color: var(--text-secondary);
  font-style: italic;
  font-size: 1.1em;
  text-align: center;
}

.hero-description {
  max-width: 700px;
  margin: var(--spacing-lg) auto;
  text-align: center;
  color: var(--text-secondary);
  font-size: 1.1em;
}

.hero-actions {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  margin-top: var(--spacing-xl);
  flex-wrap: wrap;
}

/* --- Feature Grid --- */

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-xxl);
}

.feature-card {
  background-color: var(--background-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-light);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.feature-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-medium);
}

.feature-card h3 {
  color: var(--primary);
  text-align: left;
  margin-bottom: var(--spacing-sm);
}

.feature-card p {
  color: var(--text-secondary);
  text-align: left;
}

/* --- Concept Pages --- */

.concept-count {
  text-align: center;
  color: var(--text-muted);
}

.strand-section {
  margin-bottom: var(--spacing-xxl);
}

.strand-section h2 {
  border-bottom: 2px solid var(--primary);
  padding-bottom: var(--spacing-sm);
}

.concept-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--spacing-md);
}

.concept-card {
  display: block;
  background-color: var(--background-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-md);
  text-decoration: none;
  transition: all 0.2s ease;
  box-shadow: var(--shadow-light);
}

.concept-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-medium);
  border-color: var(--primary);
  text-decoration: none;
}

.concept-card h3 {
  font-size: 1em;
  color: var(--text-primary);
  text-align: left;
  margin-bottom: var(--spacing-xs);
}

.concept-card .broader-concept {
  color: var(--text-muted);
  font-size: 0.85em;
  margin: 0;
  text-align: left;
}

.difficulty-badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 0.75em;
  font-weight: bold;
  text-transform: uppercase;
}

.difficulty-badge.basic { background-color: var(--success-bg); color: var(--success); }
.difficulty-badge.intermediate { background-color: var(--info-bg); color: var(--info); }
.difficulty-badge.advanced { background-color: var(--warning-bg); color: var(--warning); }

.concept-detail {
  max-width: 800px;
  margin: 0 auto;
}

.concept-meta {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: var(--spacing-xl);
}

.meta-item {
  color: var(--text-secondary);
  font-size: 0.9em;
}

.concept-explanation {
  background-color: var(--background-secondary);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-light);
}

/* --- Course Pages --- */

.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
}

.course-card {
  display: block;
  background-color: var(--background-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  text-decoration: none;
  transition: all 0.2s ease;
  box-shadow: var(--shadow-light);
}

.course-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-medium);
  border-color: var(--primary);
  text-decoration: none;
}

.course-card h2 {
  color: var(--primary);
  text-align: left;
}

.course-card p {
  color: var(--text-secondary);
  text-align: left;
}

.concept-list {
  max-width: 800px;
  margin: var(--spacing-lg) auto;
}

.concept-list-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-sm) var(--spacing-md);
  border-bottom: 1px solid var(--border-light);
  text-decoration: none;
  transition: background-color 0.2s ease;
}

.concept-list-item:hover {
  background-color: var(--background-secondary);
  text-decoration: none;
}

.concept-number {
  color: var(--text-muted);
  font-weight: bold;
  min-width: 30px;
}

.concept-name {
  flex: 1;
  color: var(--text-primary);
}

/* --- Content / TOC --- */

.toc {
  max-width: 800px;
  margin: 0 auto;
}

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

.toc-section h2 {
  text-align: left;
  border-bottom: 2px solid var(--primary);
  padding-bottom: var(--spacing-xs);
}

.toc-list {
  list-style: none;
  padding: 0;
}

.toc-list li {
  padding: var(--spacing-xs) 0;
  border-bottom: 1px solid var(--border-light);
}

.toc-list li a {
  display: block;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius-sm);
  transition: background-color 0.2s ease;
}

.toc-list li a:hover {
  background-color: var(--background-secondary);
  text-decoration: none;
}

/* --- Rendered Content --- */

.content-page {
  max-width: 900px;
}

.rendered-content {
  line-height: 1.8;
}

.rendered-content h1 { font-size: 2em; margin-bottom: var(--spacing-lg); }
.rendered-content h2 { font-size: 1.5em; margin-top: var(--spacing-xl); }
.rendered-content h3 { font-size: 1.2em; text-align: left; }

.rendered-content img {
  max-width: 100%;
  height: auto;
}

.rendered-content pre {
  background-color: var(--background-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-sm);
  padding: var(--spacing-md);
  overflow-x: auto;
}

.rendered-content code {
  background-color: var(--background-secondary);
  padding: 2px 6px;
  border-radius: 3px;
  font-size: 0.9em;
}

.rendered-content pre code {
  background-color: transparent;
  padding: 0;
}

.rendered-content table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--spacing-lg) 0;
}

.rendered-content th, .rendered-content td {
  border: 1px solid var(--border-secondary);
  text-align: center;
  padding: var(--spacing-sm);
}

.rendered-content th {
  font-weight: bold;
  background-color: var(--background-tertiary);
}

/* Admonitions (tip, note, warning, important) */
.admonition {
  border-radius: var(--border-radius-md);
  padding: var(--spacing-md) var(--spacing-lg);
  margin: var(--spacing-lg) 0;
  border-left: 4px solid;
}

.admonition-title {
  font-weight: bold;
  margin-bottom: var(--spacing-xs);
}

.admonition-tip { border-color: var(--success); background-color: var(--success-bg); }
.admonition-note { border-color: var(--info); background-color: var(--info-bg); }
.admonition-warning { border-color: var(--warning); background-color: var(--warning-bg); }
.admonition-important { border-color: var(--error); background-color: var(--error-bg); }
.admonition-seealso { border-color: var(--secondary); background-color: var(--background-secondary); }

/* Math display */
.math-display {
  text-align: center;
  margin: var(--spacing-lg) 0;
  font-size: 1.1em;
  overflow-x: auto;
}

.math-inline {
  font-style: italic;
}

/* --- Dashboard --- */

.dashboard-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-lg);
}

.dashboard-card {
  background-color: var(--background-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-light);
}

.dashboard-card h2 {
  text-align: left;
  font-size: 1.2em;
  margin-bottom: var(--spacing-md);
  color: var(--primary);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-md);
}

.stat {
  text-align: center;
  padding: var(--spacing-md);
  background-color: var(--background-primary);
  border-radius: var(--border-radius-md);
}

.stat-value {
  display: block;
  font-size: 2em;
  font-weight: bold;
  color: var(--primary);
}

.stat-label {
  display: block;
  font-size: 0.85em;
  color: var(--text-muted);
}

.action-buttons {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

/* --- Concept Graph --- */

.dashboard-card-full {
  grid-column: 1 / -1;
  margin-top: var(--spacing-lg);
}

.graph-controls {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-md);
  flex-wrap: wrap;
}

.graph-controls label {
  font-weight: 500;
  color: var(--text-secondary);
  white-space: nowrap;
}

.course-select {
  padding: var(--spacing-xs) var(--spacing-md);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-sm);
  font-size: 1em;
  font-family: inherit;
  background-color: var(--background-primary);
  color: var(--text-primary);
  min-width: 250px;
  cursor: pointer;
}

.course-select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.graph-container {
  background-color: var(--background-primary);
  border: 1px solid var(--border-light);
  border-radius: var(--border-radius-md);
  min-height: 200px;
  overflow: hidden;
  max-width: 100%;
}

.graph-canvas-viewport {
  position: relative;
  width: 100%;
  max-width: 100%;
  height: min(72vh, 900px);
  overflow: hidden;
  cursor: grab;
  background:
    radial-gradient(circle at 20% 20%, rgba(52, 152, 219, 0.08), transparent 28%),
    radial-gradient(circle at 80% 30%, rgba(39, 174, 96, 0.08), transparent 26%),
    linear-gradient(180deg, rgba(250, 252, 255, 0.96), rgba(244, 247, 251, 0.96));
  user-select: none;
  touch-action: none;
}

.graph-canvas-viewport:active {
  cursor: grabbing;
}

.graph-canvas-surface {
  position: absolute;
  top: 0;
  left: 0;
  will-change: transform;
}

.graph-canvas-image {
  display: block;
  max-width: none;
  height: auto;
  pointer-events: none;
}

.graph-label-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.graph-node-label {
  position: absolute;
  transform: translateX(-50%);
  max-width: 170px;
  padding: 3px 8px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid rgba(148, 163, 184, 0.45);
  box-shadow: 0 8px 18px rgba(15, 23, 42, 0.08);
  color: var(--text-primary);
  font-size: 0.76rem;
  font-weight: 600;
  line-height: 1.2;
  text-align: center;
  white-space: normal;
}

.graph-placeholder {
  text-align: center;
  color: var(--text-muted);
  padding: var(--spacing-xxl);
}

.graph-loading {
  text-align: center;
  color: var(--text-muted);
  padding: var(--spacing-xxl);
}

.graph-legend {
  display: flex;
  gap: var(--spacing-lg);
  padding: var(--spacing-sm) var(--spacing-md);
  flex-wrap: wrap;
  font-size: 0.85em;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-light);
}

/* --- Progress Bar --- */

.progress-summary {
  margin: var(--spacing-md) 0;
}

.progress-bar-stacked {
  display: flex;
  height: 24px;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  background-color: var(--background-tertiary);
}

.progress-segment {
  transition: width 0.3s ease;
}

.progress-segment.known { background-color: var(--success); }
.progress-segment.learning { background-color: var(--info); }
.progress-segment.review { background-color: var(--warning); }
.progress-segment.unknown { background-color: var(--background-tertiary); }

.progress-legend {
  display: flex;
  gap: var(--spacing-lg);
  margin-top: var(--spacing-sm);
  flex-wrap: wrap;
  justify-content: center;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-size: 0.85em;
  color: var(--text-secondary);
}

.legend-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.legend-dot.known { background-color: var(--success); }
.legend-dot.learning { background-color: var(--info); }
.legend-dot.review { background-color: var(--warning); }
.legend-dot.unknown { background-color: var(--background-tertiary); border: 1px solid var(--border-primary); }

/* --- Study Page --- */

.study-card {
  max-width: 800px;
  margin: var(--spacing-lg) auto;
  background-color: var(--background-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-medium);
}

.study-header {
  margin-bottom: var(--spacing-lg);
}

.study-header h2 {
  text-align: left;
}

.study-meta {
  display: flex;
  gap: var(--spacing-md);
  color: var(--text-secondary);
  font-size: 0.9em;
}

.state-badge {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.8em;
  font-weight: bold;
  text-transform: uppercase;
}

.state-badge.unknown { background-color: var(--background-tertiary); color: var(--text-muted); }
.state-badge.learning { background-color: var(--info-bg); color: var(--info); }
.state-badge.known { background-color: var(--success-bg); color: var(--success); }
.state-badge.review { background-color: var(--warning-bg); color: var(--warning); }

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

.study-meta-info {
  display: flex;
  gap: var(--spacing-md);
  color: var(--text-muted);
  font-size: 0.85em;
  margin-top: var(--spacing-md);
}

.study-actions {
  text-align: center;
  border-top: 1px solid var(--border-light);
  padding-top: var(--spacing-lg);
}

.study-prompt {
  font-weight: bold;
  font-size: 1.1em;
  text-align: center;
}

.study-buttons {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  margin: var(--spacing-md) 0;
}

.study-note {
  color: var(--text-muted);
  font-size: 0.85em;
  text-align: center;
}

/* --- Auth Forms --- */

.auth-prompt {
  text-align: center;
  max-width: 600px;
  margin: var(--spacing-xxl) auto;
}

.auth-actions {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  margin-top: var(--spacing-lg);
}

.auth-form-container {
  max-width: 450px;
  margin: var(--spacing-xxl) auto;
}

.auth-form {
  background-color: var(--background-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-light);
}

.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-group label {
  display: block;
  font-weight: bold;
  margin-bottom: var(--spacing-xs);
  color: var(--text-primary);
}

.form-group input {
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-sm);
  font-size: 1em;
  transition: border-color 0.2s ease;
  font-family: inherit;
}

.form-group input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.auth-switch {
  text-align: center;
  margin-top: var(--spacing-lg);
  color: var(--text-secondary);
}

.logout-form {
  margin-top: var(--spacing-xl);
}

/* --- Empty / Error States --- */

.empty-state {
  text-align: center;
  color: var(--text-muted);
  padding: var(--spacing-xxl);
}

.error {
  color: var(--error);
  text-align: center;
}

.content-error {
  text-align: center;
  padding: var(--spacing-xxl);
}

/* --- Responsive --- */

@media (max-width: 768px) {
  .site-nav {
    flex-direction: column;
    gap: var(--spacing-sm);
  }

  .nav-links {
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-sm);
  }

  .hero h1 {
    font-size: 2em;
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }

  .concept-grid {
    grid-template-columns: 1fr;
  }

  .dashboard-grid {
    grid-template-columns: 1fr;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }
}