:root {
  /* Texas A&M Official Maroon, Greys & Stealth Blacks */
  --tamu-maroon: #500000;
  --tamu-maroon-bright: #780000;
  --tamu-maroon-accent: #8b0000;
  --tamu-maroon-light: #9e1b24;
  --tamu-maroon-glow: rgba(120, 0, 0, 0.45);
  --tamu-maroon-subtle: rgba(80, 0, 0, 0.25);

  --bg-primary: #090a0c;       /* Deep stealth black */
  --bg-secondary: #121316;     /* Dark carbon */
  --bg-card: #17181c;          /* Dark charcoal grey */
  --bg-card-hover: #1e1f25;
  --border-color: #26272e;     /* Cool metallic grey border */
  --border-highlight: #3b3d45;

  --text-main: #f3f4f6;        /* Crisp silver-white */
  --text-muted: #9ca3af;       /* Neutral Aggie cool grey */
  --text-silver: #d1d5db;      /* Metallic light grey */

  --accent-blue: #780000;      /* Primary accent mapped to Aggie Maroon */
  --accent-blood: #a81c2c;     /* Deep crimson blood */
  --accent-lymph: #10b981;     /* Emerald lymph */
  --accent-gold: #d97706;      /* Warm brass / gold */

  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

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

html {
  overflow-x: hidden; /* off-screen elements (e.g. the glossary drawer, slid off via transform) must never create real horizontal scroll */
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-main);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header & Navigation */
header {
  background: rgba(18, 19, 22, 0.92);
  backdrop-filter: blur(14px);
  border-bottom: 2px solid var(--tamu-maroon);
  position: sticky;
  top: 0;
  z-index: 50;
  padding: 0.75rem 1.5rem;
  display: flex;
  flex-wrap: wrap;
  row-gap: 0.6rem;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.7);
}

.logo-area {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.logo-badge {
  background: var(--tamu-maroon);
  border: 1px solid var(--tamu-maroon-bright);
  color: #ffffff;
  font-weight: 900;
  font-size: 0.85rem;
  padding: 0.3rem 0.7rem;
  border-radius: 4px;
  letter-spacing: 0.08em;
  box-shadow: 0 2px 8px var(--tamu-maroon-glow);
}

.site-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: -0.01em;
}

.site-title span {
  color: var(--text-muted);
  font-weight: 400;
  font-size: 0.95rem;
}

.nav-tabs {
  display: flex;
  gap: 0.4rem;
  background: var(--bg-primary);
  padding: 0.25rem;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

.tab-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 0.45rem 0.9rem;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.tab-btn:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.06);
}

.tab-btn.active {
  background: var(--tamu-maroon);
  color: #ffffff;
  border: 1px solid var(--tamu-maroon-bright);
  box-shadow: 0 2px 10px var(--tamu-maroon-glow);
}

.header-actions {
  display: flex;
  gap: 0.75rem;
}

.btn-secondary {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.45rem 0.9rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  transition: all 0.2s;
}

.btn-secondary:hover {
  border-color: var(--tamu-maroon-bright);
  color: #ffffff;
  background: var(--tamu-maroon);
}

/* Main Container */
main {
  flex: 1;
  max-width: 1440px;
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem;
}

/* Paper Banner */
.paper-banner {
  background: linear-gradient(135deg, rgba(23, 24, 28, 0.95), rgba(10, 11, 14, 0.98));
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.5rem 1.75rem;
  margin-bottom: 2rem;
  position: relative;
  overflow: hidden;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
}

.paper-banner::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 6px;
  height: 100%;
  background: linear-gradient(180deg, var(--tamu-maroon-bright), var(--tamu-maroon));
}

.paper-meta {
  display: inline-block;
  background: var(--tamu-maroon-subtle);
  border: 1px solid var(--tamu-maroon);
  color: #ff9999;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 800;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  margin-bottom: 0.6rem;
}

.paper-title {
  font-size: 1.65rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  line-height: 1.3;
  color: #ffffff;
}

.paper-authors {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* Interactive Grid Layout */
.interactive-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

@media (max-width: 1024px) {
  .interactive-grid {
    grid-template-columns: 1fr;
  }
}

/* Card Styling */
.interactive-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  min-width: 0; /* prevent grid/flex blowout from unbreakable descendant content (e.g. <select> option text) */
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.35);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-color);
}

.card-title {
  font-size: 1.05rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: #ffffff;
}

.badge-tag {
  font-size: 0.7rem;
  background: var(--tamu-maroon-subtle);
  color: #ffb3b3;
  border: 1px solid rgba(120, 0, 0, 0.5);
  padding: 0.15rem 0.55rem;
  border-radius: 4px;
  font-weight: 700;
  letter-spacing: 0.03em;
}

/* Viewport Mode Toggle (Printed Model vs Live Experiment) */
.viewport-mode-toggle {
  display: flex;
  gap: 0.3rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 0.2rem;
}

.mode-toggle-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 0.3rem 0.65rem;
  border-radius: 4px;
  font-size: 0.74rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.2s;
}

.mode-toggle-btn:hover {
  color: #fff;
}

.mode-toggle-btn.active {
  background: var(--tamu-maroon);
  color: #fff;
}

/* 3D Viewport */
.viewport-3d-box {
  width: 100%;
  height: 380px;
  background: #08080a;
  border-radius: 8px;
  position: relative;
  overflow: hidden;
  border: 1px solid var(--border-color);
}

.viewport-canvas {
  width: 100%;
  height: 100%;
}

.viewport-controls {
  position: absolute;
  bottom: 10px;
  left: 10px;
  right: 10px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: rgba(18, 19, 22, 0.9);
  backdrop-filter: blur(10px);
  padding: 0.45rem 0.8rem;
  border-radius: 6px;
  border: 1px solid var(--border-color);
}

.model-select {
  background: var(--bg-secondary);
  color: #fff;
  border: 1px solid var(--border-highlight);
  padding: 0.35rem 0.65rem;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
  outline: none;
}

.model-select:focus {
  border-color: var(--tamu-maroon-bright);
}

.model-btns {
  display: flex;
  gap: 0.4rem;
}

/* Live Experiment Animation: taller canvas, controls in their own panel
   below it (never overlaid on top of the render). */
.anim-mode-box {
  height: 320px;
}

.anim-controls-panel {
  margin-top: 0.6rem;
  background: var(--bg-secondary);
  padding: 0.65rem 0.85rem;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  font-size: 0.78rem;
  color: var(--text-silver);
}

.anim-info-line {
  margin-bottom: 0.5rem;
  line-height: 1.5;
}

.anim-info-line strong {
  color: #fff;
}

.anim-caveat {
  font-size: 0.7rem;
  font-style: italic;
  color: var(--text-muted);
  margin-top: 0.4rem;
}

.anim-condition-row {
  display: flex;
  gap: 0.35rem;
  flex-wrap: wrap;
  margin-bottom: 0.4rem;
}

.anim-cond-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--border-highlight);
  color: var(--text-silver);
  padding: 0.3rem 0.6rem;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.15s;
}

.anim-cond-btn:hover {
  border-color: var(--accent-gold);
}

.anim-cond-btn.active {
  background: var(--tamu-maroon);
  border-color: var(--tamu-maroon-bright);
  color: #fff;
}

.anim-slider-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.anim-slider-row input[type="range"] {
  flex: 1;
  accent-color: var(--tamu-maroon-bright);
}

.anim-play-btn {
  background: var(--tamu-maroon);
  border: 1px solid var(--tamu-maroon-bright);
  color: #fff;
  padding: 0.3rem 0.7rem;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  cursor: pointer;
}

.anim-play-btn:hover {
  background: var(--tamu-maroon-bright);
}

.btn-icon {
  background: var(--bg-secondary);
  border: 1px solid var(--border-highlight);
  color: var(--text-silver);
  padding: 0.35rem 0.65rem;
  border-radius: 4px;
  font-size: 0.75rem;
  cursor: pointer;
  font-weight: 700;
  transition: all 0.2s;
}

.btn-icon:hover {
  background: var(--tamu-maroon);
  border-color: var(--tamu-maroon-bright);
  color: #fff;
}

/* Interactive Split-Slider ("Curtain View") */
.split-slider-container {
  position: relative;
  width: 100%;
  height: 380px;
  background: #050507;
  border-radius: 8px;
  overflow: hidden;
  user-select: none;
  cursor: ew-resize;
  border: 1px solid var(--border-color);
}

.split-layer {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

.split-layer img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  pointer-events: none;
}

.split-layer.top-layer {
  width: 50%;
  overflow: hidden;
  border-right: 2px solid var(--tamu-maroon-bright);
  box-shadow: 3px 0 15px rgba(0,0,0,0.8);
  z-index: 10;
}

.split-handle {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 38px;
  height: 38px;
  background: var(--tamu-maroon);
  border: 2px solid #ffffff;
  color: #ffffff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 900;
  box-shadow: 0 4px 15px rgba(0,0,0,0.8);
  z-index: 20;
  pointer-events: none;
}

.split-label {
  position: absolute;
  top: 10px;
  padding: 0.3rem 0.7rem;
  background: rgba(10, 11, 14, 0.85);
  backdrop-filter: blur(6px);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  border-radius: 4px;
  border: 1px solid var(--border-color);
  z-index: 15;
}

.split-label.left-label { left: 10px; border-left: 3px solid var(--tamu-maroon-bright); }
.split-label.right-label { right: 10px; border-right: 3px solid var(--text-silver); }

/* Interactive Time-Lapse Scrubber */
.scrubber-controls {
  display: flex;
  align-items: center;
  gap: 1rem;
  background: var(--bg-secondary);
  padding: 0.75rem 1rem;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

.timeline-slider {
  flex: 1;
  accent-color: var(--tamu-maroon-bright);
  cursor: pointer;
}

.timeline-ticks {
  display: flex;
  justify-content: space-between;
  margin-top: 0.3rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* T-cell Stepper */
.trafficking-stepper {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
}

.step-chip {
  flex: 1;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 0.5rem;
  border-radius: 6px;
  cursor: pointer;
  text-align: center;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  transition: all 0.2s;
}

.step-chip:hover {
  border-color: var(--border-highlight);
  color: #fff;
}

.step-chip.active {
  background: var(--tamu-maroon-subtle);
  border-color: var(--tamu-maroon-bright);
  color: #ff9999;
}

/* Live Lymphatic Model (Introduction tab) */
.lymph-live-model {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1rem 1.1rem 0.9rem;
  margin-bottom: 1.2rem;
}

.lymph-model-label {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent-lymph);
  margin-bottom: 0.6rem;
}

.lymph-model-svg {
  width: 100%;
  height: auto;
  display: block;
}

.lymph-svg-label {
  font-size: 11px;
  fill: var(--text-muted);
  font-family: inherit;
}

.lymph-model-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-top: 0.75rem;
  padding-top: 0.6rem;
  border-top: 1px dashed var(--border-color);
}

.lymph-model-legend span {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.78rem;
  color: var(--text-silver);
}

.lymph-model-legend i {
  display: inline-block;
  width: 9px;
  height: 9px;
  border-radius: 50%;
}

/* "What the Papers Mimic" cards */
.mimic-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.1rem;
}

@media (max-width: 1024px) {
  .mimic-grid {
    grid-template-columns: 1fr;
  }
}

.mimic-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-top: 3px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
}

.mimic-card-title {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.4rem;
}

.mimic-card-sub {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-silver);
  margin-bottom: 0.55rem;
  line-height: 1.4;
}

.mimic-card-detail {
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.55;
}

/* Figures Gallery & Deep Zoom */
.figures-gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

.figure-thumb-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  overflow: hidden;
  cursor: pointer;
  transition: transform 0.2s, border-color 0.2s;
}

.figure-thumb-card:hover {
  transform: translateY(-3px);
  border-color: var(--tamu-maroon-bright);
}

.figure-thumb-img {
  width: 100%;
  height: 200px;
  background: #050507;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.figure-thumb-img img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}

.figure-thumb-info {
  padding: 0.85rem;
}

.figure-thumb-title {
  font-size: 0.9rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
  color: #fff;
}

.figure-thumb-story {
  font-size: 0.83rem;
  line-height: 1.55;
  color: var(--text-silver);
  margin-bottom: 0.55rem;
}

.figure-thumb-desc {
  font-size: 0.72rem;
  line-height: 1.4;
  color: var(--text-muted);
  font-style: italic;
  padding-top: 0.5rem;
  border-top: 1px dashed var(--border-color);
}

/* Lightbox Modal (Deep Zoom) */
.lightbox-modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(5, 5, 8, 0.96);
  backdrop-filter: blur(16px);
  z-index: 100;
  flex-direction: column;
}

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

.lightbox-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: #fff;
}

.lightbox-body {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
  padding: 1rem;
}

.lightbox-img-wrapper {
  max-width: 90%;
  max-height: 85vh;
  transition: transform 0.15s ease-out;
  cursor: grab;
}

.lightbox-img-wrapper img {
  max-width: 100%;
  max-height: 85vh;
  object-fit: contain;
  box-shadow: 0 10px 40px rgba(0,0,0,0.9);
}

.lightbox-controls {
  position: absolute;
  bottom: 20px;
  display: flex;
  gap: 0.5rem;
  background: rgba(18, 19, 22, 0.9);
  padding: 0.5rem;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

/* Glossary Slide-out Drawer */
.glossary-drawer {
  position: fixed;
  top: 0;
  right: 0;
  width: min(400px, 92vw);
  height: 100vh;
  background: var(--bg-secondary);
  border-left: 2px solid var(--tamu-maroon);
  box-shadow: -15px 0 40px rgba(0,0,0,0.8);
  z-index: 90;
  transform: translateX(100%);
  transition: transform 0.3s ease;
  display: flex;
  flex-direction: column;
}

.glossary-drawer.open {
  transform: translateX(0);
}

.drawer-header {
  padding: 1.25rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--tamu-maroon);
  color: #fff;
}

.drawer-search {
  padding: 0.75rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-card);
}

.search-input {
  width: 100%;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: #fff;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  font-size: 0.85rem;
  outline: none;
}

.search-input:focus {
  border-color: var(--tamu-maroon-bright);
}

.drawer-list {
  flex: 1;
  overflow-y: auto;
  padding: 1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.term-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.9rem;
}

.term-name {
  font-weight: 700;
  color: #ff9999;
  font-size: 0.95rem;
}

.term-category {
  font-size: 0.7rem;
  background: rgba(255,255,255,0.06);
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  color: var(--text-muted);
}

.term-summary {
  font-size: 0.85rem;
  margin-bottom: 0.4rem;
}

.term-detail {
  font-size: 0.75rem;
  color: var(--text-muted);
  border-top: 1px dashed var(--border-color);
  padding-top: 0.4rem;
}

/* Cross-Paper Evaluation & Frontier Dashboard */
.frontier-container {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.frontier-hero {
  background: linear-gradient(135deg, rgba(23, 24, 28, 0.95), rgba(10, 11, 14, 0.98));
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 2rem;
  position: relative;
  overflow: hidden;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
}

.frontier-hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 6px;
  height: 100%;
  background: linear-gradient(180deg, var(--tamu-maroon-bright), var(--tamu-maroon), #400000);
}

.frontier-badge {
  display: inline-block;
  background: var(--tamu-maroon);
  border: 1px solid var(--tamu-maroon-bright);
  color: #ffffff;
  font-size: 0.8rem;
  font-weight: 800;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.75rem;
  box-shadow: 0 2px 8px var(--tamu-maroon-glow);
}

.frontier-title {
  font-size: 1.85rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  color: #ffffff;
}

.frontier-subtitle {
  color: var(--text-muted);
  font-size: 1rem;
  max-width: 820px;
}

/* Timeline Cards */
.timeline-track {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
  position: relative;
  margin: 1rem 0;
}

@media (max-width: 1024px) {
  .timeline-track {
    grid-template-columns: 1fr;
  }
}

.timeline-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: transform 0.2s, border-color 0.2s;
}

.timeline-card:hover {
  transform: translateY(-4px);
  border-color: var(--tamu-maroon-bright);
}

.timeline-year {
  font-size: 1.6rem;
  font-weight: 900;
  color: #ff8080;
  margin-bottom: 0.25rem;
}

.timeline-paper-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: #fff;
}

.timeline-scale {
  font-size: 0.75rem;
  color: var(--text-silver);
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.timeline-milestone {
  font-size: 0.85rem;
  color: var(--text-main);
  margin-bottom: 0.75rem;
  flex: 1;
}

.timeline-limitation {
  font-size: 0.75rem;
  color: #fca5a5;
  background: rgba(120, 0, 0, 0.2);
  padding: 0.4rem 0.6rem;
  border-radius: 6px;
  border-left: 3px solid var(--tamu-maroon-bright);
}

/* 5-Pillar Rubric Cards */
.pillar-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.pillar-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.75rem;
}

.pillar-icon {
  font-size: 1.5rem;
}

.pillar-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: #ffffff;
}

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

.rubric-q-box {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
  margin-bottom: 1rem;
}

.rubric-q-text {
  font-weight: 700;
  font-size: 0.95rem;
  color: #ff9999;
  margin-bottom: 0.75rem;
}

.rubric-answers-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
}

@media (max-width: 1024px) {
  .rubric-answers-grid {
    grid-template-columns: 1fr;
  }
}

.paper-answer-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 0.85rem;
}

.paper-answer-tag {
  font-size: 0.72rem;
  font-weight: 800;
  text-transform: uppercase;
  margin-bottom: 0.35rem;
  letter-spacing: 0.04em;
}

.paper-answer-text {
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--text-silver);
}

/* Frontier Prediction Cards */
.frontier-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  margin-top: 1rem;
}

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

.prediction-card {
  background: linear-gradient(135deg, rgba(23, 24, 28, 0.95), rgba(10, 11, 14, 0.98));
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.5rem;
  position: relative;
  overflow: hidden;
}

.prediction-card::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 5px;
  height: 100%;
  background: var(--tamu-maroon-bright);
}

.prediction-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: #ff9999;
  margin-bottom: 0.5rem;
}

.prediction-summary {
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  line-height: 1.4;
  color: #ffffff;
}

.prediction-detail {
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Operational Lifespan & Degradation Section */
.lifespan-card {
  margin-bottom: 2.5rem;
  border: 1px solid rgba(251, 191, 36, 0.3);
  background: linear-gradient(145deg, rgba(23, 24, 28, 0.98), rgba(18, 19, 22, 0.95));
}

.lifespan-meta-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.lifespan-stat-box {
  background: rgba(9, 10, 12, 0.65);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.85rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.lifespan-stat-box .stat-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  font-weight: 700;
}

.lifespan-stat-box .stat-value {
  font-size: 1.15rem;
  font-weight: 800;
  color: #fbbf24;
}

.lifespan-q-banner {
  background: rgba(80, 0, 0, 0.2);
  border: 1px solid rgba(120, 0, 0, 0.4);
  border-left: 4px solid var(--accent-gold);
  border-radius: 6px;
  padding: 1rem 1.25rem;
  margin-bottom: 1.25rem;
}

.lifespan-q-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 0.5rem;
  line-height: 1.4;
}

.lifespan-q-ans {
  font-size: 0.88rem;
  color: var(--text-silver);
  line-height: 1.6;
}

.lifespan-breakdown-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}

.breakdown-card {
  background: rgba(14, 15, 18, 0.8);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.breakdown-tag {
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.breakdown-desc {
  font-size: 0.82rem;
  color: var(--text-silver);
  line-height: 1.5;
}

/* Paper Q&A Interrogation Section */
.paper-qa-card {
  margin-bottom: 2.5rem;
  border-left: 4px solid var(--tamu-maroon-bright);
}

.qa-filter-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.qa-filter-btn {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.qa-filter-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

.qa-filter-btn.active {
  background: var(--tamu-maroon-bright);
  border-color: var(--tamu-maroon);
  color: #fff;
  box-shadow: 0 2px 6px var(--tamu-maroon-glow);
}

.paper-qa-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: 0.5rem;
}

.qa-item-card {
  background: rgba(14, 15, 18, 0.85);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.15rem;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.qa-item-card:hover {
  border-color: var(--border-highlight);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.qa-item-header {
  margin-bottom: 0.6rem;
}

.qa-item-meta {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.35rem;
}

.qa-category-badge {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-muted);
  font-size: 0.72rem;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
}

.qa-item-question {
  font-size: 1.02rem;
  font-weight: 700;
  color: #fff;
  line-height: 1.4;
}

.qa-item-answer {
  font-size: 0.88rem;
  color: var(--text-silver);
  line-height: 1.65;
}

.qa-item-citation {
  margin-top: 0.6rem;
  padding-top: 0.5rem;
  border-top: 1px dashed var(--border-color);
  font-size: 0.74rem;
  font-style: italic;
  color: var(--text-muted);
}

/* Presenter Beacon */
.presenter-beacon {
  position: fixed;
  bottom: 1.25rem;
  right: 1.25rem;
  z-index: 500;
  display: flex;
  align-items: center;
  gap: 0.6rem;
  background: rgba(14, 15, 18, 0.96);
  border: 1px solid var(--tamu-maroon);
  border-radius: 999px;
  padding: 0.55rem 0.7rem 0.55rem 1rem;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.45);
  font-size: 0.82rem;
  color: var(--text-silver);
  max-width: min(90vw, 420px);
}

.presenter-beacon-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #ff4d4d;
  flex-shrink: 0;
  animation: presenter-beacon-pulse 1.6s infinite ease-in-out;
}

@keyframes presenter-beacon-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.35; }
}

#presenter-beacon-text {
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.presenter-beacon .btn-icon {
  font-size: 0.74rem;
  padding: 0.25rem 0.55rem;
}

#presenter-mode-indicator {
  font-size: 0.78rem;
  font-weight: 700;
  color: #ff9999;
  background: var(--tamu-maroon-subtle);
  border: 1px solid var(--tamu-maroon);
  border-radius: 999px;
  padding: 0.2rem 0.65rem;
}

/* Overall Evaluation Scorecard Table */
.scorecard-table-wrapper {
  overflow-x: auto;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background: rgba(10, 11, 14, 0.6);
}

.scorecard-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
  text-align: left;
}

.scorecard-table th,
.scorecard-table td {
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--border-color);
  vertical-align: top;
  line-height: 1.5;
}

.scorecard-table th {
  background: rgba(18, 19, 22, 0.95);
  font-weight: 800;
  letter-spacing: 0.02em;
  border-bottom: 2px solid var(--border-highlight);
}

.scorecard-table tr:nth-child(even) {
  background: rgba(255, 255, 255, 0.015);
}

.scorecard-table tr:hover {
  background: rgba(255, 255, 255, 0.035);
}

.scorecard-dim-cell {
  color: #fbbf24;
  font-weight: 700;
  background: rgba(0, 0, 0, 0.2);
}

/* Macro vs Micro Trade-Off Analysis */
.tradeoff-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin: 1.5rem 0;
}

@media (max-width: 860px) {
  .tradeoff-grid {
    grid-template-columns: 1fr;
  }
}

.tradeoff-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.25rem 1.5rem;
}

.gained-card {
  border-left: 4px solid #10b981;
}

.sacrificed-card {
  border-left: 4px solid #ef4444;
}

.tradeoff-header {
  font-size: 1.05rem;
  font-weight: 800;
  margin-bottom: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.tradeoff-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.tradeoff-list li {
  font-size: 0.84rem;
  color: var(--text-silver);
  line-height: 1.5;
  position: relative;
  padding-left: 1.25rem;
}

.gained-card .tradeoff-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: #10b981;
  font-weight: bold;
}

.sacrificed-card .tradeoff-list li::before {
  content: "✕";
  position: absolute;
  left: 0;
  color: #ef4444;
  font-weight: bold;
}

/* ============================================================
   Responsive: Tablets, Phones & Large Displays (TVs)
   Base layout above targets a laptop/desktop monitor. These rules
   adapt it down to phone width and up to projector/TV width without
   touching the core desktop styles.
   ============================================================ */

/* Mobile nav dropdown: hidden on desktop, swaps in for .nav-tabs below
   the 900px breakpoint (see next block). */
.mobile-nav-select {
  display: none;
}

/* Tablet / narrow desktop: the 6-tab nav row no longer fits next to the
   logo and "Key Terms" button. Swap it for a single native dropdown
   instead of a horizontal-scroll strip -- clearer affordance on touch
   screens than a row that silently continues off-edge. */
@media (max-width: 900px) {
  .nav-tabs {
    display: none;
  }

  .mobile-nav-select {
    display: block;
    order: 3;
    width: 100%;
    background: var(--bg-primary);
    color: #fff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.55rem 0.75rem;
    font-size: 0.9rem;
    font-weight: 700;
    outline: none;
  }

  .mobile-nav-select:focus {
    border-color: var(--tamu-maroon-bright);
  }

  .header-actions {
    margin-left: auto;
  }
}

/* Phones */
@media (max-width: 640px) {
  header {
    padding: 0.6rem 1rem;
  }

  .site-title {
    font-size: 1rem;
  }

  .site-title span {
    display: block;
    font-size: 0.78rem;
  }

  main {
    padding: 1rem 0.85rem;
  }

  .paper-banner,
  .frontier-hero {
    padding: 1.1rem 1.25rem;
  }

  .paper-title {
    font-size: 1.25rem;
  }

  .frontier-title {
    font-size: 1.4rem;
  }

  .viewport-3d-box,
  .anim-mode-box,
  .split-slider-container {
    height: 260px;
  }

  .viewport-controls {
    flex-wrap: wrap;
    gap: 0.5rem;
  }

  .model-select {
    width: 100%;
  }

  .model-btns {
    width: 100%;
    justify-content: space-between;
  }

  /* The live lymphatic-system model (Introduction tab) is a wide labeled
     schematic. Let it scroll horizontally at a legible minimum width
     instead of shrinking its text labels below readability. */
  .lymph-live-model {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .lymph-model-svg {
    min-width: 640px;
  }

  .scorecard-table th,
  .scorecard-table td {
    padding: 0.6rem 0.7rem;
    font-size: 0.78rem;
  }

  .lifespan-meta-grid,
  .lifespan-breakdown-grid {
    grid-template-columns: 1fr;
  }
}

/* Large displays / TVs (e.g. a 60" screen viewed from across a room).
   Content already caps at a readable max-width so it never stretches
   edge-to-edge on a wide panel -- this scales type and that cap up
   together so text stays legible at couch viewing distance. */
@media (min-width: 1800px) {
  html {
    font-size: 18px;
  }

  main {
    max-width: 1680px;
  }
}