/* ==========================================================================
   BEYOND COSMIC HORIZON — Light Editorial & Celestial Observatory Stylesheet
   Compliant with Modern Web Guidance (CWV, LCP, content-visibility, a11y)
   and Strict CSP (Zero inline style attributes required)
   ========================================================================== */

:root {
  /* Light Editorial & Celestial Atlas Surfaces */
  --bg-canvas-solid: #F8FAFC;
  --bg-glass-white: rgba(255, 255, 255, 0.86);
  --bg-glass-strong: rgba(255, 255, 255, 0.94);
  --bg-subtle: #F1F5F9;

  /* Brand & Astrophysical Accents */
  --accent-primary: #0284C7;
  --accent-primary-hover: #0369A1;
  --accent-sky-light: #E0F2FE;
  --accent-indigo: #4F46E5;
  --accent-indigo-light: #EEF2FF;
  --accent-amber: #EA580C;
  --accent-amber-light: #FFEDD5;

  /* Typography Colors */
  --text-primary: #0F172A;
  --text-secondary: #334155;
  --text-muted: #64748B;

  /* Borders & Shadows */
  --border-subtle: rgba(203, 213, 225, 0.88);
  --border-sky: #BAE6FD;
  --shadow-card: 0 10px 30px -10px rgba(15, 23, 42, 0.07);
  --shadow-hover: 0 16px 36px -10px rgba(2, 132, 199, 0.14);

  /* Typography Families */
  --font-display: 'Space Grotesk', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-sans: 'Plus Jakarta Sans', 'Inter', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  /* Spacing & Radii */
  --radius-xl: 18px;
  --radius-lg: 14px;
  --radius-md: 10px;
  --radius-pill: 9999px;
}

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

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

body {
  font-family: var(--font-sans);
  color: var(--text-primary);
  background-color: var(--bg-canvas-solid);
  background-image:
    radial-gradient(circle at 12% 16%, rgba(56, 189, 248, 0.16) 0%, transparent 38%),
    radial-gradient(circle at 88% 20%, rgba(99, 102, 241, 0.15) 0%, transparent 42%),
    radial-gradient(circle at 76% 84%, rgba(251, 146, 60, 0.12) 0%, transparent 40%),
    linear-gradient(180deg, #F0F7FF 0%, #F8FAFC 48%, #F1F5F9 100%);
  background-attachment: fixed;
  line-height: 1.6;
  min-height: 100dvh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* Interactive Celestial Star-Chart & Orbital Background Canvas */
#space-bg-canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 0;
}

.site-wrapper {
  position: relative;
  z-index: 1;
  max-width: 1280px;
  margin: 0 auto;
  padding: 1.25rem 1.25rem 4rem;
}

/* Skip to Content Link for Accessibility */
.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  background: var(--accent-primary);
  color: #FFFFFF;
  padding: 0.6rem 1rem;
  border-radius: var(--radius-md);
  font-weight: 700;
  z-index: 100;
  text-decoration: none;
}
.skip-link:focus {
  top: 1rem;
}

/* Tabular Numerals for Science Stats & Telemetry */
.tabular-nums {
  font-variant-numeric: tabular-nums;
}

/* Frosted White Editorial Surface */
.glass-card {
  background: var(--bg-glass-white);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-card);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.glass-card-interactive:hover {
  transform: translateY(-2px);
  border-color: #7DD3FC;
  box-shadow: var(--shadow-hover);
}

/* Science Fact of the Day Hero Gradient Card */
.fact-hero-card {
  background: linear-gradient(135deg, rgba(224, 242, 254, 0.92) 0%, rgba(219, 234, 254, 0.92) 55%, rgba(224, 231, 255, 0.95) 100%);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-sky);
  border-radius: var(--radius-xl);
  box-shadow: 0 14px 34px -8px rgba(2, 132, 199, 0.15);
}

/* Corner-Reticle Callout Box (Light Mode Observatory Accent) */
.reticle-box {
  position: relative;
  background: linear-gradient(135deg, rgba(240, 249, 255, 0.92) 0%, rgba(238, 242, 255, 0.92) 100%);
  border: 1px solid var(--border-sky);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
}
.reticle-box::before,
.reticle-box::after {
  content: "";
  position: absolute;
  width: 9px;
  height: 9px;
  pointer-events: none;
}
.reticle-box::before {
  top: -1px;
  left: -1px;
  border-top: 2.5px solid var(--accent-primary);
  border-left: 2.5px solid var(--accent-primary);
}
.reticle-box::after {
  bottom: -1px;
  right: -1px;
  border-bottom: 2.5px solid var(--accent-primary);
  border-right: 2.5px solid var(--accent-primary);
}

/* ==========================================================================
   TOP NAVIGATION BAR & SPACE BACKGROUND SWITCHER
   ========================================================================== */
.top-utility-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.55rem 1rem;
  margin-bottom: 0.75rem;
  font-size: 0.75rem;
  background: rgba(255, 255, 255, 0.78);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
}

.bg-switcher-group {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
}

.bg-mode-btn {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.3rem 0.65rem;
  border-radius: 8px;
  border: 1px solid var(--border-subtle);
  background: #FFFFFF;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}
.bg-mode-btn.is-active,
.bg-mode-btn:hover {
  background: var(--accent-sky-light);
  color: var(--accent-primary-hover);
  border-color: #7DD3FC;
}

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem 1.5rem;
  margin-bottom: 1.5rem;
}

.brand-group {
  display: flex;
  align-items: center;
  gap: 1.75rem;
}

.brand-logo {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-icon {
  width: 38px;
  height: 38px;
  border-radius: 12px;
  background: var(--accent-sky-light);
  border: 1px solid var(--border-sky);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
}

.brand-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 0.9rem;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.primary-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.35rem;
  list-style: none;
}

.nav-link {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  padding-bottom: 0.2rem;
  border-bottom: 2px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.nav-link:hover,
.nav-link.is-active {
  color: var(--accent-primary);
  border-color: var(--accent-primary);
}

.header-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.65rem;
}

.search-input {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  padding: 0.5rem 0.9rem;
  border-radius: 12px;
  border: 1px solid var(--border-subtle);
  background: var(--bg-subtle);
  color: var(--text-primary);
  min-width: 210px;
  outline: none;
  transition: border-color 0.15s ease, background-color 0.15s ease;
}
.search-input:focus {
  background: #FFFFFF;
  border-color: var(--accent-primary);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 700;
  padding: 0.55rem 1rem;
  border-radius: 11px;
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.15s ease;
}

.btn-primary {
  background: var(--accent-primary);
  color: #FFFFFF;
}
.btn-primary:hover {
  background: var(--accent-primary-hover);
}

.btn-outline {
  background: #FFFFFF;
  color: var(--text-primary);
  border-color: #CBD5E1;
}
.btn-outline:hover {
  background: var(--bg-subtle);
  border-color: #94A3B8;
}

/* Badges & Pills */
.badge {
  display: inline-flex;
  align-items: center;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.2rem 0.55rem;
  border-radius: 6px;
  line-height: 1.2;
}
.badge-sky {
  background: var(--accent-sky-light);
  color: var(--accent-primary-hover);
}
.badge-indigo {
  background: var(--accent-indigo-light);
  color: #4338CA;
}
.badge-amber {
  background: var(--accent-amber-light);
  color: #C2410C;
}

/* ==========================================================================
   HERO SPLIT SECTION (7 COLUMNS VIDEO + ARTICLE / 5 COLUMNS FACT OF THE DAY)
   ========================================================================== */
.hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  margin-bottom: 2rem;
}

@media (min-width: 1024px) {
  .hero-grid {
    grid-template-columns: 7fr 5fr;
  }
}

.hero-spotlight-card {
  padding: 1.35rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.section-eyebrow {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-secondary);
  margin-bottom: 0.85rem;
}

.hero-inner-split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem;
  align-items: center;
}

@media (min-width: 768px) {
  .hero-inner-split {
    grid-template-columns: 12fr 13fr;
  }
}

.video-thumb-wrapper {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: #060913;
  display: block;
}

.video-thumb-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.play-overlay-btn {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(15, 23, 42, 0.72);
  border: 1.5px solid rgba(255, 255, 255, 0.85);
  color: #FFFFFF;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  pointer-events: none;
}

.duration-pill {
  position: absolute;
  bottom: 0.55rem;
  right: 0.55rem;
  background: rgba(9, 13, 22, 0.86);
  color: #FFFFFF;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.15rem 0.45rem;
  border-radius: 6px;
}

.hero-headline {
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 2vw, 1.55rem);
  font-weight: 800;
  line-height: 1.2;
  color: var(--text-primary);
  margin: 0.55rem 0;
}

.hero-summary {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-bottom: 0.9rem;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

/* Fact of the Day Card */
.fact-of-day-card {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.fact-stat-display {
  font-family: var(--font-mono);
  font-size: clamp(1.45rem, 2.3vw, 1.95rem);
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.15;
  margin: 0.6rem 0 0.75rem;
}

.fact-explanation {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.fact-footer {
  margin-top: 1.25rem;
  padding-top: 0.85rem;
  border-top: 1px solid rgba(186, 230, 253, 0.9);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.75rem;
}

.text-link-btn {
  background: none;
  border: none;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-primary);
  cursor: pointer;
  text-decoration: underline;
}
.text-link-btn:hover {
  color: var(--accent-primary-hover);
}

/* ==========================================================================
   TOPIC FILTER BAR
   ========================================================================== */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 1.75rem;
}

.topic-pills-group {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
}

.topic-pill {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.42rem 0.9rem;
  border-radius: var(--radius-pill);
  border: 1px solid var(--border-subtle);
  background: var(--bg-glass-white);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}
.topic-pill.is-active,
.topic-pill:hover {
  background: var(--accent-primary);
  color: #FFFFFF;
  border-color: var(--accent-primary);
}

/* ==========================================================================
   CORE WEB VITALS: DEFERRED OFF-SCREEN SECTIONS (modern-web-guidance)
   ========================================================================== */
.cwv-deferred-section {
  content-visibility: auto;
  contain-intrinsic-size: auto none auto 380px;
  margin-bottom: 2.25rem;
}

.section-header-row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.9rem;
}

.section-heading {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--text-primary);
}

.section-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Daily Science Facts 4-Column Strip */
.facts-strip-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}
@media (min-width: 640px) {
  .facts-strip-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (min-width: 1024px) {
  .facts-strip-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.fact-mini-card {
  padding: 0.95rem;
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
}

.fact-mini-thumb {
  width: 58px;
  height: 66px;
  border-radius: 10px;
  flex-shrink: 0;
  object-fit: cover;
  background: #090D16;
}

.fact-mini-title {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 0.25rem 0 0.2rem;
}

.fact-mini-text {
  font-size: 0.75rem;
  color: var(--text-secondary);
  line-height: 1.45;
}

/* Latest Video Companion Articles 3-Column Grid */
.articles-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem;
}
@media (min-width: 768px) {
  .articles-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.article-card {
  padding: 1rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 0.85rem;
  text-decoration: none;
  color: inherit;
}

.article-card-top {
  display: grid;
  grid-template-columns: 5fr 7fr;
  gap: 0.85rem;
  align-items: center;
}

.article-card-title {
  font-family: var(--font-display);
  font-size: 0.92rem;
  font-weight: 800;
  line-height: 1.28;
  color: var(--text-primary);
}

.article-card-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin: 0.25rem 0;
}

.article-card-summary {
  font-size: 0.78rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ==========================================================================
   INTERACTIVE COSMIC SCALE EXPLORER MODULE
   ========================================================================== */
.scale-explorer-card {
  padding: 1.5rem;
}

.scale-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  align-items: center;
}
@media (min-width: 768px) {
  .scale-grid {
    grid-template-columns: 5fr 7fr;
  }
}

.scale-canvas-box {
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1rem;
  display: flex;
  justify-content: center;
}

.scale-range-input {
  width: 100%;
  margin: 0.6rem 0;
  accent-color: var(--accent-primary);
  cursor: pointer;
}

.scale-ticks {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* ==========================================================================
   AEO / GEO SCIENTIFIC TELEMETRY TABLE & FAQ ACCORDION
   ========================================================================== */
.telemetry-table-wrap {
  overflow-x: auto;
  margin-top: 0.75rem;
}

.telemetry-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.8125rem;
  text-align: left;
}

.telemetry-table th,
.telemetry-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border-subtle);
}

.telemetry-table th {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--text-primary);
  background: rgba(241, 245, 249, 0.75);
}

.faq-list {
  display: grid;
  gap: 0.75rem;
}

.faq-item {
  padding: 1rem 1.25rem;
}

.faq-question {
  font-family: var(--font-display);
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-primary);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.faq-answer {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: 0.65rem;
  padding-top: 0.65rem;
  border-top: 1px solid var(--border-subtle);
}

/* ==========================================================================
   MODAL DIALOGS (CREATOR QUICK-PUBLISH STUDIO & ARTICLE READER)
   ========================================================================== */
.modal-dialog {
  margin: auto;
  width: min(94vw, 980px);
  max-height: 90dvh;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  background: #FFFFFF;
  color: var(--text-primary);
  box-shadow: 0 25px 50px -12px rgba(15, 23, 42, 0.25);
  padding: 0;
  overflow-y: auto;
}

.modal-dialog::backdrop {
  background: rgba(15, 23, 42, 0.45);
  backdrop-filter: blur(4px);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.15rem 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
  background: var(--bg-subtle);
}

.modal-body {
  padding: 1.5rem;
}

.form-grid {
  display: grid;
  gap: 1rem;
}

.form-row-2 {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}
@media (min-width: 640px) {
  .form-row-2 {
    grid-template-columns: 1fr 1fr;
  }
}

.form-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
}

.form-control {
  width: 100%;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  padding: 0.6rem 0.85rem;
  border-radius: 10px;
  border: 1px solid #CBD5E1;
  background: #FFFFFF;
  color: var(--text-primary);
  outline: none;
}
.form-control:focus {
  border-color: var(--accent-primary);
}

.chapter-pills-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0.85rem 0;
}

.chapter-btn {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.35rem 0.7rem;
  border-radius: 8px;
  border: 1px solid var(--border-subtle);
  background: var(--bg-subtle);
  color: var(--text-secondary);
  cursor: pointer;
}
.chapter-btn.is-active,
.chapter-btn:hover {
  background: var(--accent-sky-light);
  color: var(--accent-primary-hover);
  border-color: #7DD3FC;
  font-weight: 700;
}

/* Toast Notification */
.toast-banner {
  position: fixed;
  bottom: 1.25rem;
  right: 1.25rem;
  background: #0F172A;
  color: #FFFFFF;
  padding: 0.75rem 1.15rem;
  border-radius: 12px;
  font-size: 0.8125rem;
  font-weight: 600;
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.25);
  z-index: 90;
}
.is-hidden {
  display: none !important;
}

/* Utility Spacing Classes (Strict CSP — No inline style attributes) */
.mt-md {
  margin-top: 1.25rem;
}
.mt-lg {
  margin-top: 1.75rem;
}
.article-hero-figure {
  margin: 1.5rem 0;
  max-height: 380px;
}

/* Footer */
.site-footer {
  margin-top: 3rem;
  padding: 1.5rem;
  font-size: 0.75rem;
  color: var(--text-muted);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 1rem;
}

/* ==========================================================================
   MOTION & ACCESSIBILITY SAFETY (modern-web-guidance compliant)
   ========================================================================== */
@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;
  }
}