/* ============================================
   Curious World — style.css
   A calm curiosity engine
   ============================================ */

/* --- Reset & Base --- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg: #0a0a0b;
  --surface: #111113;
  --surface-hover: #161618;
  --border: #1e1e22;
  --border-hover: #2a2a30;
  --text-primary: #ededef;
  --text-secondary: #8b8b8e;
  --text-tertiary: #5c5c60;
  --accent: #6366f1;
  --accent-dim: rgba(99, 102, 241, 0.08);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', monospace;
  --max-width: 680px;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
}

/* --- Grid Background --- */
.grid-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.015) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.015) 1px, transparent 1px);
  background-size: 80px 80px;
  mask-image: radial-gradient(ellipse 60% 40% at 50% 0%, black 0%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse 60% 40% at 50% 0%, black 0%, transparent 70%);
}

/* --- Header --- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 24px;
  background: rgba(10, 10, 11, 0.9);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.back {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text-tertiary);
  text-decoration: none;
  transition: color 0.2s;
}

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

.header-right {
  display: flex;
  align-items: center;
  gap: 16px;
}

.visit-count {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-tertiary);
}

.curiosity-toggle {
  padding: 8px 14px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 12px;
  cursor: pointer;
  transition: all 0.2s;
}

.curiosity-toggle:hover {
  background: var(--surface);
  border-color: var(--border-hover);
  color: var(--text-primary);
}

/* --- Main --- */
.main {
  position: relative;
  z-index: 1;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px 60px;
}

/* --- Hero --- */
.hero {
  text-align: center;
  padding: 60px 0 40px;
  margin-bottom: 32px;
}

.hero-title {
  font-size: clamp(28px, 5vw, 40px);
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.hero-subtitle {
  font-size: 15px;
  color: var(--text-tertiary);
  margin-bottom: 24px;
}

.theme {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
}

.theme-icon {
  font-size: 14px;
}

.theme-name {
  color: var(--text-primary);
}

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

/* --- Today's Lens --- */
.lens-section {
  margin-bottom: 48px;
}

.lens-card {
  padding: 24px 28px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  border-left: 3px solid var(--accent);
}

.lens-label {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  display: block;
  margin-bottom: 12px;
}

.lens-prompt {
  font-size: 17px;
  font-style: italic;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* --- Section Title --- */
.section-title {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.section-title::after {
  content: '';
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--border), transparent);
}

/* --- Feed --- */
.feed {
  display: flex;
  flex-direction: column;
  gap: 1px;
  background: var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.feed-section {
  margin-bottom: 48px;
}

/* --- Feed Item --- */
.feed-item {
  background: var(--surface);
  padding: 24px;
  animation: fadeIn 0.4s ease-out both;
}

.feed-item:first-child {
  border-radius: 12px 12px 0 0;
}

.feed-item:last-child {
  border-radius: 0 0 12px 12px;
}

.feed-item:only-child {
  border-radius: 12px;
}

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

.item-source {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--text-tertiary);
  margin-bottom: 8px;
}

.item-title {
  font-size: 17px;
  font-weight: 500;
  line-height: 1.4;
  margin-bottom: 10px;
}

.item-title a {
  color: var(--text-primary);
  text-decoration: none;
  transition: color 0.2s;
}

.item-title a:hover {
  color: var(--accent);
}

.item-context {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.6;
}

.item-topics {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.topics-label {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
}

.topic-btn {
  padding: 5px 10px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: 12px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}

.topic-btn:hover {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--text-primary);
}

.topic-btn.explored {
  color: var(--text-tertiary);
  border-style: dashed;
}

.topic-btn.explored:hover {
  color: var(--text-primary);
  border-style: solid;
}

/* --- Loading --- */
.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 60px 0;
  color: var(--text-tertiary);
  font-size: 13px;
}

.loading-spinner {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-top-color: var(--text-tertiary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* --- Lesson Panel --- */
.lesson-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.85);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s ease;
}

.lesson-overlay.active {
  opacity: 1;
  visibility: visible;
}

.lesson-panel {
  position: relative;
  width: 100%;
  max-width: 560px;
  max-height: 85vh;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  transform: translateY(16px);
  transition: transform 0.25s ease;
}

.lesson-overlay.active .lesson-panel {
  transform: translateY(0);
}

.lesson-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 32px;
  height: 32px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-tertiary);
  font-size: 18px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  z-index: 10;
}

.lesson-close:hover {
  background: var(--surface-hover);
  color: var(--text-primary);
}

.lesson-content {
  padding: 32px;
  overflow-y: auto;
  max-height: 85vh;
}

.lesson-title {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 16px;
  padding-right: 40px;
}

.lesson-definition {
  font-size: 15px;
  color: var(--text-secondary);
  padding: 16px;
  background: var(--bg);
  border-radius: 8px;
  margin-bottom: 24px;
  line-height: 1.6;
}

.lesson-body {
  margin-bottom: 24px;
}

.lesson-body p {
  font-size: 15px;
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.7;
}

.lesson-body p:last-child {
  margin-bottom: 0;
}

.lesson-model {
  margin: 24px 0;
  padding: 20px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
}

.lesson-model-label {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  margin-bottom: 8px;
}

.lesson-model-name {
  font-size: 15px;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.lesson-model-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.5;
}

.lesson-followup {
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
}

.lesson-followup-title {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  margin-bottom: 12px;
}

.lesson-followup-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.followup-topic {
  padding: 6px 12px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: 13px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}

.followup-topic:hover {
  border-color: var(--accent);
  color: var(--text-primary);
}

.lesson-links {
  margin-top: 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.lesson-link {
  font-size: 13px;
  color: var(--text-tertiary);
  text-decoration: none;
  transition: color 0.2s;
}

.lesson-link:hover {
  color: var(--accent);
}

/* --- Curiosity Panel --- */
.curiosity-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.85);
  z-index: 200;
  display: flex;
  align-items: flex-start;
  justify-content: flex-end;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s ease;
}

.curiosity-overlay.active {
  opacity: 1;
  visibility: visible;
}

.curiosity-panel {
  position: relative;
  width: 100%;
  max-width: 380px;
  height: 100vh;
  background: var(--surface);
  border-left: 1px solid var(--border);
  overflow-y: auto;
  transform: translateX(100%);
  transition: transform 0.25s ease;
}

.curiosity-overlay.active .curiosity-panel {
  transform: translateX(0);
}

.curiosity-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 32px;
  height: 32px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-tertiary);
  font-size: 18px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  z-index: 10;
}

.curiosity-close:hover {
  background: var(--surface-hover);
  color: var(--text-primary);
}

.curiosity-content {
  padding: 32px 24px;
}

.curiosity-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 4px;
}

.curiosity-intro {
  font-size: 13px;
  color: var(--text-tertiary);
  margin-bottom: 28px;
}

.curiosity-stats {
  display: flex;
  gap: 32px;
  margin-bottom: 32px;
}

.curiosity-stat {
  display: flex;
  flex-direction: column;
}

.curiosity-stat .stat-value {
  font-size: 28px;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1;
}

.curiosity-stat .stat-label {
  font-size: 11px;
  color: var(--text-tertiary);
  margin-top: 4px;
}

.curiosity-categories {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-bottom: 32px;
}

.curiosity-category {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
}

.category-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.category-icon {
  font-size: 14px;
}

.category-name {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-primary);
}

.category-topics {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.category-topic {
  font-size: 12px;
  color: var(--text-secondary);
  padding: 4px 8px;
  background: var(--surface);
  border-radius: 4px;
}

.category-empty {
  font-size: 12px;
  color: var(--text-tertiary);
  font-style: italic;
}

.curiosity-clear {
  width: 100%;
  padding: 10px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-tertiary);
  font-size: 12px;
  cursor: pointer;
  transition: all 0.2s;
}

.curiosity-clear:hover {
  border-color: var(--text-tertiary);
  color: var(--text-secondary);
}

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

.footer p {
  font-size: 13px;
  color: var(--text-tertiary);
}

/* --- Error State --- */
.error-message {
  text-align: center;
  padding: 40px;
  color: var(--text-tertiary);
}

.error-message p {
  margin-bottom: 16px;
}

.retry-btn {
  padding: 8px 16px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-secondary);
  font-size: 13px;
  cursor: pointer;
  transition: all 0.2s;
}

.retry-btn:hover {
  background: var(--surface);
  color: var(--text-primary);
}

.empty-message {
  text-align: center;
  padding: 40px;
  color: var(--text-tertiary);
  font-size: 14px;
}

/* --- Responsive --- */
@media (max-width: 640px) {
  .header {
    padding: 12px 16px;
  }

  .main {
    padding: 70px 16px 40px;
  }

  .hero {
    padding: 40px 0 32px;
  }

  .hero-title {
    font-size: 26px;
  }

  .lens-card {
    padding: 20px;
  }

  .lens-prompt {
    font-size: 15px;
  }

  .feed-item {
    padding: 20px;
  }

  .item-title {
    font-size: 15px;
  }

  .curiosity-panel {
    max-width: 100%;
  }

  .lesson-panel {
    max-height: 90vh;
    margin: 16px;
  }

  .lesson-content {
    padding: 24px;
  }
}