:root {
  --bg-dark: #000000;
  --bg-card: #000000;
  --border-color: #262626;
  --border-hover: #ffffff;
  --text-primary: #ffffff;
  --text-secondary: #a3a3a3;
  --text-muted: #525252;
  --accent-white: #ffffff;
  
  --font-heading: 'Space Grotesk', sans-serif;
  --font-body: 'Plus Jakarta Sans', sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;
}

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

body {
  background-color: var(--bg-dark);
  color: var(--text-primary);
  font-family: var(--font-body);
  line-height: 1.6;
  overflow-x: hidden;
  padding: 0;
  margin: 0;
}

.app-container {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Hero Header */
.hero-header {
  padding: 80px 24px 60px 24px;
  text-align: center;
  max-width: 1100px;
  margin: 0 auto;
  position: relative;
}

.header-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--text-primary);
  background: transparent;
  border: 1px solid var(--border-color);
  padding: 6px 14px;
  border-radius: 100px;
  margin-bottom: 24px;
  animation: float 4s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-4px); }
}

.main-title {
  font-family: var(--font-heading);
  font-size: 3.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 700px;
  margin: 0 auto 20px auto;
  font-weight: 300;
}

/* Start Here Section */
.start-here-section {
  text-align: left;
  max-width: 800px;
  margin: 40px auto 0 auto;
  border-top: 1px solid var(--border-color);
  padding-top: 40px;
}

.start-here-title {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 16px;
  text-transform: uppercase;
}

.start-here-intro {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 30px;
}

.seed-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 24px 32px;
  border-radius: 12px;
  max-width: 800px;
  margin: 0 auto;
  position: relative;
  overflow: hidden;
}

.seed-box::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: var(--text-primary);
}

.seed-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.seed-text {
  font-size: 1.05rem;
  color: var(--text-primary);
  font-style: italic;
  line-height: 1.5;
  font-weight: 400;
}

/* Paths Section */
.paths-section {
  max-width: 1200px;
  width: 100%;
  margin: 0 auto 50px auto;
  padding: 0 24px;
}

.section-title {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.section-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 30px;
}

.paths-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
  margin-bottom: 24px;
}

.path-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 24px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  transition: all 0.2s ease;
  height: 100%;
}

.path-card:hover {
  border-color: var(--border-hover);
}

.path-card.active {
  border-color: var(--text-primary);
  background: rgba(255, 255, 255, 0.05);
}

.path-problem {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 12px;
  line-height: 1.4;
  display: block;
}

.path-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
  display: block;
}

.path-description {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Active Path Banner */
.active-path-banner {
  background: #000000;
  border: 1px solid var(--text-primary);
  border-radius: 8px;
  padding: 16px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 20px;
  font-size: 0.95rem;
}

.active-path-banner.hidden {
  display: none;
}

.clear-path-btn {
  background: var(--text-primary);
  color: var(--bg-dark);
  border: none;
  font-family: var(--font-body);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 8px 16px;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.clear-path-btn:hover {
  background: var(--text-secondary);
}

/* Controls & Filter Panel */
.controls-panel {
  max-width: 1200px;
  width: 100%;
  margin: 0 auto 30px auto;
  padding: 0 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.search-wrapper {
  position: relative;
  width: 100%;
}

.search-icon {
  position: absolute;
  left: 18px;
  top: 50%;
  transform: translateY(-50%);
  width: 20px;
  height: 20px;
  color: var(--text-muted);
}

#search-input {
  width: 100%;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 1rem;
  padding: 16px 16px 16px 50px;
  border-radius: 12px;
  outline: none;
  transition: all 0.3s ease;
}

#search-input:focus {
  border-color: var(--border-hover);
}

.filter-wrapper {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 500;
  padding: 10px 18px;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: all 0.2s ease;
}

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

.filter-btn.active {
  background: var(--text-primary);
  border-color: var(--text-primary);
  color: var(--bg-dark);
}

.btn-icon {
  font-size: 1rem;
  filter: grayscale(100%);
}

/* Stats Bar */
.stats-bar {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  max-width: 1200px;
  width: 100%;
  margin: 0 auto 40px auto;
  padding: 0 24px;
  gap: 20px;
}

.stat-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 20px;
  text-align: center;
}

.stat-val {
  display: block;
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1;
  margin-bottom: 6px;
}

.stat-lbl {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-family: var(--font-mono);
}

/* Table of Contents List */
.toc-container {
  display: flex;
  flex-direction: column;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 0 24px 80px 24px;
}

.toc-row {
  display: flex;
  align-items: flex-start;
  padding: 30px 0;
  border-bottom: 1px solid var(--border-color);
  transition: all 0.2s ease;
}

.toc-row:hover {
  border-bottom-color: var(--border-hover);
}

.toc-number {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-muted);
  width: 60px;
  flex-shrink: 0;
  padding-top: 2px;
}

.toc-details {
  flex-grow: 1;
}

.toc-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
  gap: 16px;
}

.toc-title {
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--text-primary);
}

.toc-description {
  font-size: 0.95rem;
  color: var(--text-secondary);
  max-width: 900px;
  line-height: 1.6;
}

.toc-actions {
  margin-left: 40px;
  align-self: center;
  flex-shrink: 0;
}

.volume-number {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  background: transparent;
  border: 1px solid var(--border-color);
  padding: 4px 8px;
  border-radius: 4px;
}

.cluster-badge {
  font-size: 0.75rem;
  color: var(--text-secondary);
  background: transparent;
  padding: 4px 10px;
  border-radius: 100px;
  border: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  gap: 6px;
}

.cluster-badge-icon {
  font-size: 0.85rem;
  filter: grayscale(100%);
}

.detail-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 8px 16px;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.detail-btn:hover {
  background: var(--text-primary);
  color: var(--bg-dark);
  border-color: var(--text-primary);
}

/* Modal Styling */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.9);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  padding: 20px;
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-content {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  max-width: 600px;
  width: 100%;
  padding: 40px;
  position: relative;
  transform: scale(0.95);
  transition: transform 0.3s ease;
}

.modal-overlay.active .modal-content {
  transform: scale(1);
}

.close-modal {
  position: absolute;
  top: 24px;
  right: 24px;
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  width: 24px;
  height: 24px;
  transition: color 0.2s ease;
}

.close-modal:hover {
  color: var(--text-primary);
}

.modal-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

.modal-title-text {
  font-family: var(--font-heading);
  font-size: 1.85rem;
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.modal-description-text {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 32px;
}

.modal-scaffolding {
  border-top: 1px solid var(--border-color);
  padding-top: 24px;
  margin-bottom: 36px;
}

.modal-scaffolding h4 {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.15em;
  margin-bottom: 16px;
}

.scaffolding-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.scaffold-item {
  display: flex;
  gap: 16px;
  align-items: flex-start;
}

.scaffold-bullet {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-primary);
  background: transparent;
  border: 1px solid var(--border-color);
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 4px;
  flex-shrink: 0;
}

.scaffold-title {
  display: block;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 2px;
}

.scaffold-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
}

.primary-modal-btn {
  background: var(--text-primary);
  color: var(--bg-dark);
  border: none;
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 12px 24px;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.primary-modal-btn:hover {
  background: var(--text-secondary);
}

/* Footer */
.app-footer {
  border-top: 1px solid var(--border-color);
  padding: 40px 24px;
  text-align: center;
  margin-top: auto;
}

.footer-text {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-text strong {
  color: var(--text-primary);
}

/* Responsive adjustments */
@media(max-width: 768px) {
  .main-title {
    font-size: 2.25rem;
  }
  .hero-header {
    padding: 60px 16px 40px 16px;
  }
  .stats-bar {
    grid-template-columns: 1fr;
    gap: 12px;
  }
  .modal-content {
    padding: 30px 20px;
  }
  .toc-row {
    flex-direction: column;
    gap: 16px;
  }
  .toc-actions {
    margin-left: 0;
    align-self: flex-start;
  }
}