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

:root {
  --bg: #18181a;
  --bg-panel: #1e1e20;
  --bg-panel-hover: #252527;
  --border: rgba(212,203,184,0.08);
  --text: #d4cbb8;
  --text-dim: #8a8478;
  --accent: #d4cbb8;
  --accent-dim: #5a5650;
  --red: #f85149;
  --green: #3fb950;
  --orange: #d29922;
  --radius: 8px;
  --panel-width: 280px;
}

html, body {
  height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  overflow: hidden;
}

/* ── Header ───────────────────────────────────────────────── */
header {
  height: 48px;
  display: flex;
  align-items: center;
  padding: 0 20px;
  border-bottom: 1px solid var(--border);
  background: var(--bg-panel);
  flex-shrink: 0;
}

header h1 {
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.02em;
}

header .subtitle {
  color: var(--text-dim);
  font-weight: 400;
  margin-left: 8px;
}

/* ── Main Layout ──────────────────────────────────────────── */
main {
  display: flex;
  height: calc(100% - 48px - 32px); /* header + footer */
  overflow: hidden;
}

/* ── Panels ───────────────────────────────────────────────── */
.panel {
  width: var(--panel-width);
  min-width: var(--panel-width);
  background: var(--bg-panel);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.right-panel {
  border-right: none;
  border-left: 1px solid var(--border);
}

.panel-header {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
  flex-shrink: 0;
}

.panel-header h2 {
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-dim);
}

.collapse-icon {
  font-size: 10px;
  color: var(--text-dim);
  transition: transform 0.2s;
}

.panel-header.collapsed .collapse-icon {
  transform: rotate(-90deg);
}

.panel-body {
  padding: 12px 16px;
  overflow-y: auto;
  flex: 1;
}

.panel-body.collapsed {
  display: none;
}

/* ── Controls ─────────────────────────────────────────────── */
.control-group {
  margin-bottom: 16px;
}

.control-group label {
  display: block;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-dim);
  margin-bottom: 6px;
}

.control-group label span {
  color: var(--accent);
  font-weight: 600;
}

input[type="range"] {
  width: 100%;
  height: 4px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--border);
  border-radius: 2px;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
}

.range-labels {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--text-dim);
  margin-top: 4px;
}

.preset-grid, .viz-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px;
}

.preset-btn, .viz-btn, .draw-btn {
  padding: 6px 8px;
  font-size: 11px;
  font-weight: 500;
  border: 1px solid rgba(212,203,184,0.08);
  border-radius: var(--radius);
  background: rgba(212,203,184,0.06);
  color: var(--text-dim);
  cursor: pointer;
  transition: all 0.15s;
}

.preset-btn:hover, .viz-btn:hover, .draw-btn:hover {
  background: var(--bg-panel-hover);
  color: var(--text);
}

.preset-btn.active, .viz-btn.active, .draw-btn.active {
  border-color: rgba(212,203,184,0.15);
  color: var(--accent);
  background: rgba(212,203,184,0.14);
}

.buttons-row {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.action-btn {
  flex: 1;
  min-width: 70px;
  padding: 7px 10px;
  font-size: 11px;
  font-weight: 500;
  border: 1px solid rgba(212,203,184,0.08);
  border-radius: var(--radius);
  background: rgba(212,203,184,0.06);
  color: var(--text);
  cursor: pointer;
  transition: all 0.15s;
}

.action-btn:hover {
  background: var(--bg-panel-hover);
  border-color: var(--text-dim);
}

/* ── Canvas Area ──────────────────────────────────────────── */
#canvas-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 12px;
  min-width: 0;
  position: relative;
  background: #000;
}

#sim-canvas {
  display: block;
  width: 100%;
  height: calc(100% - 40px);
  border-radius: 4px;
  cursor: crosshair;
  image-rendering: pixelated;
  object-fit: contain;
}

#drag-tooltip {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(30, 30, 32, 0.9);
  border: 1px solid var(--border);
  color: var(--text-dim);
  padding: 8px 16px;
  border-radius: 6px;
  font-size: 13px;
  pointer-events: none;
  transition: opacity 0.5s ease;
  z-index: 10;
}

#colorbar {
  margin-top: 8px;
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 300px;
  max-width: 80%;
}

#colorbar-canvas {
  width: 100%;
  height: 12px;
  border-radius: 2px;
}

.colorbar-labels {
  display: flex;
  justify-content: space-between;
  width: 100%;
  font-size: 10px;
  color: var(--text-dim);
  margin-top: 2px;
}

#colorbar-label {
  font-weight: 500;
}

/* ── Education Panel ──────────────────────────────────────── */
.edu-section {
  margin-bottom: 16px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
}

.edu-section:last-child {
  border-bottom: none;
  margin-bottom: 0;
}

.edu-section h3 {
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text);
}

.edu-section p, .edu-section ol {
  font-size: 12px;
  line-height: 1.6;
  color: var(--text-dim);
}

.edu-section p + p,
.edu-section p + ol {
  margin-top: 8px;
}

.edu-section ol {
  padding-left: 18px;
}

.edu-section strong {
  color: var(--text);
}

#regime-title {
  color: var(--accent);
}

/* ── Footer ───────────────────────────────────────────────── */
footer {
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-top: 1px solid var(--border);
  background: var(--bg-panel);
  flex-shrink: 0;
}

footer p {
  font-size: 10px;
  color: var(--text-dim);
  letter-spacing: 0.04em;
}

/* ── Mobile ───────────────────────────────────────────────── */
@media (max-width: 900px) {
  main {
    flex-direction: column;
    height: calc(100% - 48px - 32px);
  }

  .panel {
    width: 100%;
    min-width: 100%;
    border-right: none;
    border-left: none;
    border-bottom: 1px solid var(--border);
    order: 2;
  }

  .right-panel {
    order: 3;
    border-left: none;
  }

  #canvas-container {
    order: 1;
    min-height: 300px;
    flex: 1;
  }

  .panel-body {
    max-height: 200px;
  }

  /* Start panels collapsed on mobile */
  .panel-body.mobile-collapse,
  .panel-body.collapsed {
    display: none;
  }

  .panel-header.mobile-collapse .collapse-icon,
  .panel-header.collapsed .collapse-icon {
    transform: rotate(-90deg);
  }
}

@media (max-width: 600px) {
  header h1 {
    font-size: 14px;
  }

  header .subtitle {
    display: none;
  }

  .preset-grid {
    grid-template-columns: 1fr 1fr;
  }

  #canvas-container {
    padding: 6px;
    min-height: 250px;
  }
}

/* ── Scrollbar ────────────────────────────────────────────── */
.panel-body::-webkit-scrollbar {
  width: 6px;
}

.panel-body::-webkit-scrollbar-track {
  background: transparent;
}

.panel-body::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}