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

/* ─── Dark mode (default) ─── */
:root {
  --bg: #0d0d14;
  --node-color: #7b6cf6;
  --node-glow: rgba(123, 108, 246, 0.5);
  --node-hover: #a99ef8;
  --link-color: rgba(123, 108, 246, 0.2);
  --label-color: rgba(220, 215, 255, 0.85);
  --panel-bg: rgba(18, 16, 32, 0.97);
  --panel-border: rgba(123, 108, 246, 0.25);
  --text-primary: #e8e4ff;
  --text-secondary: rgba(200, 195, 240, 0.6);
  --accent: #7b6cf6;
  --overlay-bg: rgba(0, 0, 0, 0.45);
  --btn-bg: rgba(123, 108, 246, 0.12);
  --btn-border: rgba(123, 108, 246, 0.3);
  --btn-bg-hover: rgba(123, 108, 246, 0.24);
  --btn-border-hover: rgba(123, 108, 246, 0.55);
  --close-hover-bg: rgba(255, 255, 255, 0.06);
}

/* ─── Light mode: OS auto ─── */
@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #f0eeff;
    --node-color: #6b5ce7;
    --node-glow: rgba(107, 92, 231, 0.35);
    --node-hover: #8b7cf6;
    --link-color: rgba(107, 92, 231, 0.3);
    --label-color: rgba(50, 40, 100, 0.9);
    --panel-bg: rgba(248, 246, 255, 0.97);
    --panel-border: rgba(107, 92, 231, 0.2);
    --text-primary: #1e1850;
    --text-secondary: rgba(80, 70, 140, 0.65);
    --accent: #6b5ce7;
    --overlay-bg: rgba(80, 70, 140, 0.25);
    --btn-bg: rgba(107, 92, 231, 0.1);
    --btn-border: rgba(107, 92, 231, 0.28);
    --btn-bg-hover: rgba(107, 92, 231, 0.2);
    --btn-border-hover: rgba(107, 92, 231, 0.5);
    --close-hover-bg: rgba(0, 0, 0, 0.05);
  }
}

/* ─── Light mode: manual override ─── */
:root[data-theme="light"] {
  --bg: #f0eeff;
  --node-color: #6b5ce7;
  --node-glow: rgba(107, 92, 231, 0.35);
  --node-hover: #8b7cf6;
  --link-color: rgba(107, 92, 231, 0.3);
  --label-color: rgba(50, 40, 100, 0.9);
  --panel-bg: rgba(248, 246, 255, 0.97);
  --panel-border: rgba(107, 92, 231, 0.2);
  --text-primary: #1e1850;
  --text-secondary: rgba(80, 70, 140, 0.65);
  --accent: #6b5ce7;
  --overlay-bg: rgba(80, 70, 140, 0.25);
  --btn-bg: rgba(107, 92, 231, 0.1);
  --btn-border: rgba(107, 92, 231, 0.28);
  --btn-bg-hover: rgba(107, 92, 231, 0.2);
  --btn-border-hover: rgba(107, 92, 231, 0.5);
  --close-hover-bg: rgba(0, 0, 0, 0.05);
}

/* ─── Dark mode: manual override ─── */
:root[data-theme="dark"] {
  --bg: #0d0d14;
  --node-color: #7b6cf6;
  --node-glow: rgba(123, 108, 246, 0.5);
  --node-hover: #a99ef8;
  --link-color: rgba(123, 108, 246, 0.2);
  --label-color: rgba(220, 215, 255, 0.85);
  --panel-bg: rgba(18, 16, 32, 0.97);
  --panel-border: rgba(123, 108, 246, 0.25);
  --text-primary: #e8e4ff;
  --text-secondary: rgba(200, 195, 240, 0.6);
  --accent: #7b6cf6;
  --overlay-bg: rgba(0, 0, 0, 0.45);
  --btn-bg: rgba(123, 108, 246, 0.12);
  --btn-border: rgba(123, 108, 246, 0.3);
  --btn-bg-hover: rgba(123, 108, 246, 0.24);
  --btn-border-hover: rgba(123, 108, 246, 0.55);
  --close-hover-bg: rgba(255, 255, 255, 0.06);
}

body {
  background: var(--bg);
  color: var(--text-primary);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Noto Sans JP", sans-serif;
  height: 100dvh;
  overflow: hidden;
  position: relative;
  transition: background 0.3s;
}

/* ─── Graph canvas ─── */
#graph {
  width: 100%;
  height: 100dvh;
  display: block;
  cursor: grab;
}

#graph:active {
  cursor: grabbing;
}

.node circle {
  fill: var(--node-color);
  filter: drop-shadow(0 0 6px var(--node-glow));
  cursor: pointer;
  transition: r 0.2s, fill 0.2s;
}

.node:hover circle {
  fill: var(--node-hover);
  filter: drop-shadow(0 0 12px var(--node-glow));
}

.node text {
  fill: var(--label-color);
  font-size: 12px;
  pointer-events: none;
  user-select: none;
  text-anchor: middle;
  dominant-baseline: middle;
}

.link {
  stroke: var(--link-color);
  stroke-width: 1px;
}

/* ─── Detail panel ─── */
#panel {
  position: fixed;
  top: 0;
  right: 0;
  height: 100dvh;
  width: min(380px, 100vw);
  background: var(--panel-bg);
  border-left: 1px solid var(--panel-border);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  transform: translateX(100%);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  z-index: 100;
}

#panel.open {
  transform: translateX(0);
}

.panel-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 28px 22px 20px;
  border-bottom: 1px solid var(--panel-border);
}

.panel-icon {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: rgba(123, 108, 246, 0.15);
  border: 2px solid rgba(123, 108, 246, 0.35);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 26px;
  flex-shrink: 0;
}

.panel-title {
  font-size: 18px;
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1.3;
}

.panel-close {
  margin-left: auto;
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 6px;
  border-radius: 6px;
  font-size: 18px;
  line-height: 1;
  transition: color 0.15s, background 0.15s;
  flex-shrink: 0;
}

.panel-close:hover {
  color: var(--text-primary);
  background: var(--close-hover-bg);
}

.panel-body {
  padding: 20px 22px;
  flex: 1;
}

.panel-description {
  font-size: 15px;
  line-height: 1.7;
  color: var(--text-primary);
  margin-bottom: 20px;
  word-break: break-all;
}

.panel-photos {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 4px;
}

.panel-photos img {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
  border-radius: 4px;
  background: rgba(123, 108, 246, 0.08);
}

.panel-photos .photo-placeholder {
  width: 100%;
  aspect-ratio: 1;
  border-radius: 4px;
  background: rgba(123, 108, 246, 0.07);
  border: 1px dashed rgba(123, 108, 246, 0.2);
}

/* ─── Overlay (mobile) ─── */
#overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--overlay-bg);
  z-index: 99;
}

#overlay.visible {
  display: block;
}

/* ─── Hint ─── */
#hint {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 12px;
  color: var(--text-secondary);
  pointer-events: none;
  white-space: nowrap;
}

/* ─── Controls (top-left buttons) ─── */
#controls {
  position: fixed;
  top: 16px;
  left: 16px;
  z-index: 200;
  display: flex;
  gap: 8px;
}

#controls button {
  background: var(--btn-bg);
  border: 1px solid var(--btn-border);
  color: var(--label-color);
  font-family: inherit;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  padding: 6px 12px;
  border-radius: 20px;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

#controls button:hover {
  background: var(--btn-bg-hover);
  border-color: var(--btn-border-hover);
  color: var(--text-primary);
}

/* ─── Mobile ─── */
@media (max-width: 480px) {
  #panel {
    top: auto;
    bottom: 0;
    left: 0;
    right: 0;
    width: 100%;
    height: 75dvh;
    border-left: none;
    border-top: 1px solid var(--panel-border);
    border-radius: 20px 20px 0 0;
    transform: translateY(100%);
  }

  #panel.open {
    transform: translateY(0);
  }

  .panel-header {
    padding: 16px 18px 14px;
  }

  .panel-body {
    padding: 14px 18px;
  }

  #hint {
    bottom: 14px;
  }
}