:root {
  color-scheme: dark;
  --bg-deep: #04060d;
  --panel-bg: rgba(9, 13, 24, 0.76);
  --panel-bg-elevated: rgba(15, 22, 38, 0.88);
  --panel-border: rgba(120, 175, 255, 0.18);
  --panel-border-strong: rgba(120, 195, 255, 0.36);
  --text-primary: #eef4ff;
  --text-secondary: #9bb0d1;
  --text-muted: #647899;
  --accent-cyan: #38bdf8;
  --accent-cyan-glow: rgba(56, 189, 248, 0.38);
  --accent-amber: #f59e0b;
  --accent-amber-glow: rgba(245, 158, 11, 0.35);
  --accent-violet: #a855f7;
  --accent-rose: #f43f5e;
  --accent-emerald: #10b981;
  --scrollbar-thumb: #3b5278;
  --scrollbar-track: #0b101e;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', 'Menlo', monospace;
  accent-color: var(--accent-cyan);
}

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

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-deep);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.45;
  -webkit-font-smoothing: antialiased;
}

::selection {
  background: rgba(56, 189, 248, 0.32);
  color: #ffffff;
}

/* Custom scrollbars following modern-web-guidance */
.scroller {
  --scrollbar-thumb: #3b5278;
  --scrollbar-track: #0b101e;
  scrollbar-color: var(--scrollbar-thumb) var(--scrollbar-track);
  scrollbar-width: thin;
}

@supports not (scrollbar-color: auto) {
  .scroller::-webkit-scrollbar {
    width: 8px;
    height: 8px;
  }
  .scroller::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
    border-radius: 4px;
  }
  .scroller::-webkit-scrollbar-track {
    background: var(--scrollbar-track);
  }
}

/* WebGL Viewport */
#viewport-container {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  z-index: 1;
}

#gl-canvas {
  width: 100%;
  height: 100%;
  display: block;
  cursor: grab;
  touch-action: none;
}

#gl-canvas:active {
  cursor: grabbing;
}

/* HUD Layout Layer */
.hud-layer {
  position: fixed;
  inset: 0;
  z-index: 10;
  pointer-events: none;
  display: grid;
  grid-template-rows: auto 1fr auto;
  grid-template-columns: 340px 1fr 330px;
  gap: 12px;
  padding: 14px;
}

.hud-interactive {
  pointer-events: auto;
}

/* Glassmorphism Panel Base */
.glass-panel {
  background: var(--panel-bg);
  backdrop-filter: blur(16px) saturate(145%);
  -webkit-backdrop-filter: blur(16px) saturate(145%);
  border: 1px solid var(--panel-border);
  border-radius: 14px;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.55), inset 0 1px 0 rgba(255, 255, 255, 0.08);
  transition: border-color 0.2s ease, transform 0.25s ease, opacity 0.25s ease;
}

.glass-panel:hover {
  border-color: rgba(120, 195, 255, 0.28);
}

/* Top Header Bar */
.top-bar {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 10px 16px;
}

.brand-group {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-icon {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: radial-gradient(circle at 38% 38%, #000 0%, #000 32%, #f59e0b 45%, #38bdf8 66%, transparent 74%);
  box-shadow: 0 0 18px rgba(56, 189, 248, 0.5);
  position: relative;
  flex-shrink: 0;
}

.brand-icon::after {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: 50%;
  border: 1.5px dashed rgba(56, 189, 248, 0.45);
  animation: spinSlow 14s linear infinite;
}

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

.brand-title {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  background: linear-gradient(95deg, #ffffff 0%, #bae6fd 55%, #fcd34d 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  text-wrap: balance;
}

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

/* Phase Pill Indicator */
.phase-indicator {
  display: flex;
  align-items: center;
  gap: 8px;
  background: rgba(8, 12, 24, 0.72);
  border: 1px solid var(--panel-border);
  padding: 5px 12px;
  border-radius: 999px;
}

.phase-step {
  font-size: 0.74rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 999px;
  color: var(--text-muted);
  transition: all 0.2s ease;
}

.phase-step.active-inspiral {
  background: rgba(56, 189, 248, 0.18);
  color: #7dd3fc;
  box-shadow: 0 0 12px rgba(56, 189, 248, 0.25);
}

.phase-step.active-merger {
  background: rgba(244, 63, 94, 0.25);
  color: #fda4af;
  box-shadow: 0 0 16px rgba(244, 63, 94, 0.45);
}

.phase-step.active-ringdown {
  background: rgba(168, 85, 247, 0.22);
  color: #d8b4fe;
  box-shadow: 0 0 12px rgba(168, 85, 247, 0.35);
}

.phase-divider {
  color: var(--text-muted);
  font-size: 0.7rem;
}

/* Top Bar Actions */
.top-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
  flex-wrap: wrap;
}

.btn {
  appearance: none;
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-primary);
  border: 1px solid rgba(148, 185, 255, 0.2);
  border-radius: 9px;
  padding: 7px 12px;
  font-family: inherit;
  font-size: 0.78rem;
  font-weight: 500;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: background 0.18s ease, border-color 0.18s ease, transform 0.12s ease, box-shadow 0.18s ease;
  user-select: none;
}

.btn:hover {
  background: rgba(56, 189, 248, 0.14);
  border-color: var(--accent-cyan);
}

.btn:active {
  transform: translateY(1px);
}

.btn-primary {
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.28), rgba(14, 116, 144, 0.45));
  border-color: rgba(56, 189, 248, 0.55);
  color: #f0f9ff;
}

.btn-primary:hover {
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.4), rgba(14, 116, 144, 0.6));
  box-shadow: 0 0 16px var(--accent-cyan-glow);
}

.btn-amber {
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.22), rgba(180, 83, 9, 0.35));
  border-color: rgba(245, 158, 11, 0.5);
  color: #fef3c7;
}

.btn-amber:hover {
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.35), rgba(180, 83, 9, 0.5));
  border-color: var(--accent-amber);
  box-shadow: 0 0 14px var(--accent-amber-glow);
}

.btn-icon {
  padding: 7px 9px;
}

.btn.is-active {
  background: rgba(56, 189, 248, 0.24);
  border-color: var(--accent-cyan);
  color: #7dd3fc;
}

/* Language switcher: a segmented EN | RU control that matches the top-bar buttons */
.lang-switch {
  display: inline-flex;
  border: 1px solid rgba(148, 185, 255, 0.2);
  border-radius: 9px;
  overflow: hidden;
}

.lang-btn {
  appearance: none;
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-secondary);
  border: 0;
  padding: 7px 10px;
  font-family: inherit;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: background 0.18s ease, color 0.18s ease;
}

.lang-btn + .lang-btn {
  border-left: 1px solid rgba(148, 185, 255, 0.2);
}

.lang-btn:hover {
  background: rgba(56, 189, 248, 0.14);
  color: var(--text-primary);
}

.lang-btn[aria-pressed="true"] {
  background: rgba(56, 189, 248, 0.24);
  color: #7dd3fc;
  cursor: default;
}

.lang-btn:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: -2px;
}

/* Side Panels (Left: Controls, Right: Scientific Telemetry) */
.side-panel {
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-height: 100%;
  overflow-y: auto;
  padding: 10px 12px;
}

.left-panel {
  grid-column: 1;
  grid-row: 2;
}

.right-panel {
  grid-column: 3;
  grid-row: 2;
}

.hud-hidden .left-panel,
.hud-hidden .right-panel {
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 4px;
  border-bottom: 1px solid rgba(148, 185, 255, 0.14);
  margin-bottom: 4px;
}

.section-title {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent-cyan);
}

.section-badge {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  color: var(--text-secondary);
  background: rgba(255, 255, 255, 0.05);
  padding: 1px 6px;
  border-radius: 5px;
}

/* Event Presets Grid */
.preset-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 5px;
}

.preset-btn {
  text-align: left;
  padding: 5px 8px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(148, 185, 255, 0.14);
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.16s ease;
}

.preset-btn:hover {
  background: rgba(56, 189, 248, 0.12);
  border-color: rgba(56, 189, 248, 0.45);
}

.preset-btn.active {
  background: rgba(56, 189, 248, 0.2);
  border-color: var(--accent-cyan);
  box-shadow: inset 0 0 10px rgba(56, 189, 248, 0.15);
}

.preset-name {
  font-size: 0.74rem;
  font-weight: 600;
  display: block;
  color: #e0f2fe;
}

.preset-desc {
  font-size: 0.65rem;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

/* Control Sliders */
.control-group {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.control-group + .control-group {
  margin-top: 4px;
}

.control-label-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-size: 0.74rem;
}

.control-label {
  color: var(--text-secondary);
}

.control-value {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

/* Custom Range Sliders */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.12);
  border-radius: 999px;
  outline: none;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 999px;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--accent-cyan);
  border: 2px solid #ffffff;
  box-shadow: 0 0 10px var(--accent-cyan-glow);
  margin-top: -4.5px;
  transition: transform 0.12s ease, background-color 0.15s ease;
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
  background: #7dd3fc;
}

input[type="range"]::-moz-range-track {
  height: 6px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.12);
}

input[type="range"]::-moz-range-thumb {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--accent-cyan);
  border: 2px solid #ffffff;
  box-shadow: 0 0 10px var(--accent-cyan-glow);
}

/* Checkboxes using label:has(:checked) */
.toggle-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
}

.toggle-chip {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 7px;
  border-radius: 7px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(148, 185, 255, 0.14);
  font-size: 0.71rem;
  color: var(--text-secondary);
  cursor: pointer;
  user-select: none;
  transition: all 0.15s ease;
}

.toggle-chip:hover {
  border-color: rgba(56, 189, 248, 0.35);
  color: var(--text-primary);
}

.toggle-chip:has(input:checked) {
  background: rgba(56, 189, 248, 0.16);
  border-color: rgba(56, 189, 248, 0.55);
  color: #e0f2fe;
}

.toggle-chip input[type="checkbox"] {
  width: 14px;
  height: 14px;
  margin: 0;
  accent-color: var(--accent-cyan);
}

/* Camera View Pill Row */
.camera-pills {
  display: flex;
  gap: 5px;
  flex-wrap: wrap;
}

.camera-pills .btn {
  flex: 1 1 auto;
  justify-content: center;
  padding: 5px 8px;
  font-size: 0.72rem;
}

/* Right Panel: Scientific Telemetry Cards */
.telemetry-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
}

.telemetry-card {
  background: rgba(6, 10, 20, 0.62);
  border: 1px solid rgba(148, 185, 255, 0.13);
  border-radius: 10px;
  padding: 8px 10px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.telemetry-card.span-2 {
  grid-column: span 2;
}

.telemetry-label {
  font-size: 0.69rem;
  color: var(--text-secondary);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.telemetry-symbol {
  font-family: var(--font-mono);
  color: var(--accent-cyan);
  font-size: 0.68rem;
}

.telemetry-value {
  font-family: var(--font-mono);
  font-size: 0.96rem;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

.telemetry-value.highlight-amber {
  color: #fbbf24;
}

.telemetry-value.highlight-cyan {
  color: #38bdf8;
}

.telemetry-value.highlight-rose {
  color: #fb7185;
}

.telemetry-sub {
  font-size: 0.66rem;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
}

/* Velocity / Relativistic Meter Bar */
.meter-track {
  width: 100%;
  height: 5px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 999px;
  overflow: hidden;
  margin-top: 4px;
}

.meter-fill {
  height: 100%;
  width: 20%;
  background: linear-gradient(90deg, #38bdf8 0%, #f59e0b 65%, #f43f5e 100%);
  border-radius: 999px;
  transition: width 0.06s linear;
}

/* Bottom Timeline & LIGO Strain Oscilloscope Bar */
.bottom-bar {
  grid-column: 1 / -1;
  grid-row: 3;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px 16px;
}

.timeline-controls-row {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.playback-buttons {
  display: flex;
  align-items: center;
  gap: 6px;
}

.play-btn {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  justify-content: center;
  padding: 0;
  font-size: 1rem;
}

.timeline-scrubber-wrap {
  flex: 1 1 320px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.timeline-scrubber-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.71rem;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

#timeline-slider {
  height: 8px;
  background: linear-gradient(90deg,
    rgba(56, 189, 248, 0.35) 0%,
    rgba(56, 189, 248, 0.5) 75%,
    rgba(244, 63, 94, 0.75) 82%,
    rgba(168, 85, 247, 0.45) 100%
  );
}

.speed-control-compact {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 175px;
}

/* LIGO Strain Waveform Canvas */
.waveform-container {
  position: relative;
  width: 100%;
  height: 76px;
  background: rgba(3, 6, 14, 0.78);
  border: 1px solid rgba(120, 175, 255, 0.16);
  border-radius: 10px;
  overflow: hidden;
  cursor: ew-resize;
}

#waveform-canvas {
  width: 100%;
  height: 100%;
  display: block;
}

.waveform-legend {
  position: absolute;
  top: 6px;
  left: 10px;
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.69rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
  pointer-events: none;
}

.legend-dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  margin-right: 4px;
}

.waveform-hint {
  position: absolute;
  top: 6px;
  right: 10px;
  font-size: 0.68rem;
  color: var(--text-muted);
  pointer-events: none;
}

/* Scientific Info Modal (<dialog>) */
dialog.science-dialog {
  margin: auto;
  max-width: 720px;
  width: calc(100% - 32px);
  max-height: 84vh;
  background: var(--panel-bg-elevated);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  color: var(--text-primary);
  border: 1px solid var(--panel-border-strong);
  border-radius: 18px;
  padding: 0;
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.8);
}

dialog.science-dialog::backdrop {
  background: rgba(2, 4, 10, 0.72);
  backdrop-filter: blur(6px);
}

.dialog-inner {
  padding: 22px 26px;
  overflow-y: auto;
  max-height: 84vh;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.dialog-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid rgba(148, 185, 255, 0.16);
  padding-bottom: 12px;
}

.dialog-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: #e0f2fe;
}

.science-article {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.science-card {
  background: rgba(8, 13, 26, 0.65);
  border: 1px solid rgba(148, 185, 255, 0.14);
  border-radius: 12px;
  padding: 14px;
}

.science-card h3 {
  font-size: 0.88rem;
  color: var(--accent-cyan);
  margin-bottom: 6px;
}

.science-card p {
  font-size: 0.79rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

.formula-box {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #fde68a;
  background: rgba(245, 158, 11, 0.09);
  border: 1px solid rgba(245, 158, 11, 0.25);
  padding: 6px 9px;
  border-radius: 6px;
  margin-top: 8px;
}

/* Responsive adjustments */
@media (max-width: 1120px) {
  .hud-layer {
    grid-template-columns: 300px 1fr 290px;
  }
}

@media (max-width: 900px) {
  .hud-layer {
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr auto;
    overflow-y: auto;
  }
  .left-panel, .right-panel {
    display: none;
  }
  .science-article {
    grid-template-columns: 1fr;
  }
}