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

:root {
  --bg:           #0b0d14;
  --surface:      #13161f;
  --surface2:     #1c1f2e;
  --border:       #252838;
  --border-soft:  #1e2130;
  --text:         #e2e8f0;
  --text-dim:     #a0aec0;
  --muted:        #5c6680;
  --accent:       #5b8dee;
  --accent-soft:  rgba(91,141,238,0.15);

  --topic:        #4C9BE8;
  --subtopic:     #63b3ed;
  --paper:        #F6AD55;
  --researcher:   #68D391;

  --header-h:     56px;
  --statsbar-h:   30px;
  --panel-w:      380px;
  --radius:       8px;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* ── Header ──────────────────────────────────────────────────────────── */
header {
  height: var(--header-h);
  display: flex;
  align-items: center;
  padding: 0 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  gap: 16px;
  z-index: 20;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  flex-shrink: 0;
}

.logo-mark {
  width: 26px;
  height: 26px;
  border-radius: 6px;
  background: linear-gradient(135deg, var(--topic) 0%, var(--researcher) 100%);
  flex-shrink: 0;
}

.header-left h1 {
  font-size: 0.95rem;
  font-weight: 700;
  white-space: nowrap;
  color: var(--text);
}

.subtitle {
  display: block;
  font-size: 0.68rem;
  color: var(--muted);
  white-space: nowrap;
}

/* ── Search ──────────────────────────────────────────────────────────── */
.header-center { flex: 1; display: flex; justify-content: center; }

.search-wrap {
  position: relative;
  width: 100%;
  max-width: 420px;
  display: flex;
  align-items: center;
}

.search-icon {
  position: absolute;
  left: 10px;
  width: 16px;
  height: 16px;
  color: var(--muted);
  pointer-events: none;
}

#search {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 7px 36px 7px 34px;
  border-radius: var(--radius);
  font-size: 0.85rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}
#search::placeholder { color: var(--muted); }
#search:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

#search-shortcut {
  position: absolute;
  right: 10px;
  font-size: 0.65rem;
  color: var(--muted);
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 5px;
  pointer-events: none;
}

/* ── Filters ─────────────────────────────────────────────────────────── */
.header-right { flex-shrink: 0; }

.filters { display: flex; gap: 4px; }

.filter-btn {
  display: flex;
  align-items: center;
  gap: 5px;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 4px 11px;
  border-radius: 20px;
  font-size: 0.76rem;
  font-family: inherit;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
}
.filter-btn:hover { border-color: var(--accent); color: var(--text); }
.filter-btn.active { background: var(--accent); border-color: var(--accent); color: #fff; }

.filter-dot {
  width: 7px; height: 7px;
  border-radius: 50%;
  flex-shrink: 0;
}
.filter-dot.topic      { background: var(--topic); }
.filter-dot.subtopic   { background: var(--subtopic); }
.filter-dot.paper      { background: var(--paper); }
.filter-dot.researcher { background: var(--researcher); }
.filter-btn.active .filter-dot { opacity: 0.8; }

/* ── Stats bar ───────────────────────────────────────────────────────── */
#stats-bar {
  height: var(--statsbar-h);
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--border-soft);
  font-size: 0.72rem;
  color: var(--muted);
  flex-shrink: 0;
}

.stat-sep { opacity: 0.4; }
.stat-right { margin-left: auto; }

/* ── Main layout ─────────────────────────────────────────────────────── */
#main {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

#graph-container {
  flex: 1;
  position: relative;
  overflow: hidden;
}

#graph {
  width: 100%;
  height: 100%;
  display: block;
}

/* ── Loading ─────────────────────────────────────────────────────────── */
#loading {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  background: var(--bg);
  color: var(--muted);
  font-size: 0.85rem;
  z-index: 5;
}

.spinner {
  width: 28px; height: 28px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.75s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

#loading.hidden { display: none; }

/* ── Zoom controls ───────────────────────────────────────────────────── */
#zoom-controls {
  position: absolute;
  bottom: 24px;
  right: 20px;
  display: flex;
  flex-direction: column;
  gap: 3px;
  z-index: 10;
}

#zoom-controls button {
  width: 34px; height: 34px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  transition: background 0.15s, color 0.15s;
  display: flex; align-items: center; justify-content: center;
}
#zoom-controls button:hover { background: var(--surface2); color: var(--text); }

/* ── Detail panel ────────────────────────────────────────────────────── */
#panel {
  width: var(--panel-w);
  background: var(--surface);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  overflow: hidden;
  transition: transform 0.3s ease;
}
#panel.hidden { display: none; }

#panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px 0;
  flex-shrink: 0;
}

#panel-type-badge {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  padding: 2px 8px;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent);
}

#panel-close {
  width: 26px; height: 26px;
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--muted);
  cursor: pointer;
  font-size: 0.8rem;
  display: flex; align-items: center; justify-content: center;
  transition: all 0.15s;
}
#panel-close:hover { background: var(--surface2); color: var(--text); }

/* Panel content — scrollable area */
#panel > *:not(#panel-header) {
  padding-left: 16px;
  padding-right: 16px;
}

#panel-title {
  font-size: 0.95rem;
  font-weight: 700;
  line-height: 1.45;
  padding-top: 12px;
  padding-bottom: 0;
}

#panel-meta {
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-top: 8px;
  line-height: 1.7;
  display: flex;
  flex-wrap: wrap;
  gap: 4px 0;
}

.meta-chip {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 7px;
  font-size: 0.72rem;
  color: var(--text-dim);
  margin-right: 5px;
  margin-bottom: 4px;
}
.meta-chip.journal { color: var(--paper); border-color: rgba(246,173,85,0.3); background: rgba(246,173,85,0.08); }
.meta-chip.year    { color: var(--muted); }
.meta-chip.section { color: var(--accent); border-color: var(--accent-soft); background: var(--accent-soft); }

#panel-section {
  font-size: 0.73rem;
  color: var(--accent);
  margin-top: 6px;
  font-style: italic;
}

#panel-summary {
  font-size: 0.83rem;
  line-height: 1.75;
  color: var(--text-dim);
  margin-top: 14px;
  padding-bottom: 0;
}

#panel-actions {
  display: flex;
  gap: 8px;
  margin-top: 14px;
  flex-wrap: wrap;
}

.action-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 5px 12px;
  border-radius: var(--radius);
  font-size: 0.77rem;
  font-family: inherit;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.15s;
  border: 1px solid var(--border);
  color: var(--accent);
  background: var(--accent-soft);
}
.action-btn:hover { background: rgba(91,141,238,0.25); }

#panel-connected {
  margin-top: 20px;
  flex: 1;
  overflow-y: auto;
  padding-bottom: 20px;
  border-top: 1px solid var(--border-soft);
  padding-top: 14px;
}

.panel-section-label {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--muted);
  margin-bottom: 8px;
}

#panel-links {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.connected-node {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 10px;
  background: var(--bg);
  border-radius: 6px;
  font-size: 0.79rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: border-color 0.15s, background 0.15s;
  color: var(--text-dim);
}
.connected-node:hover { border-color: var(--border); background: var(--surface2); color: var(--text); }

.connected-node .node-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.connected-node .node-type-label {
  font-size: 0.65rem;
  text-transform: uppercase;
  color: var(--muted);
  margin-left: auto;
  flex-shrink: 0;
}

/* ── Legend ──────────────────────────────────────────────────────────── */
#legend {
  position: fixed;
  bottom: 20px;
  left: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 10px 14px;
  border-radius: var(--radius);
  z-index: 10;
}

.legend-title {
  font-size: 0.62rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--muted);
  margin-bottom: 7px;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.76rem;
  color: var(--text-dim);
  margin-bottom: 4px;
}
.legend-item:last-child { margin-bottom: 0; }

.dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  display: inline-block;
  flex-shrink: 0;
}
.topic-dot      { background: var(--topic); }
.subtopic-dot   { background: var(--subtopic); }
.paper-dot      { background: var(--paper); }
.researcher-dot { background: var(--researcher); }

/* ── Graph node labels ───────────────────────────────────────────────── */
.node-label {
  font-size: 10.5px;
  fill: var(--text-dim);
  pointer-events: none;
  text-anchor: middle;
  font-family: 'Inter', system-ui, sans-serif;
}

/* ── Tooltip ─────────────────────────────────────────────────────────── */
#tooltip {
  position: fixed;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 8px 12px;
  font-size: 0.78rem;
  color: var(--text);
  pointer-events: none;
  z-index: 50;
  max-width: 260px;
  line-height: 1.5;
  box-shadow: 0 4px 16px rgba(0,0,0,0.4);
}
#tooltip.hidden { display: none; }

.tooltip-type {
  font-size: 0.62rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 3px;
  opacity: 0.7;
}

.tooltip-label { font-weight: 600; }

.tooltip-sub {
  font-size: 0.73rem;
  color: var(--text-dim);
  margin-top: 2px;
}

/* ── Search results ──────────────────────────────────────────────────── */
#search-results {
  position: absolute;
  top: calc(100% + 4px);
  left: 0;
  right: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  z-index: 200;
  overflow: hidden;
  box-shadow: 0 8px 24px rgba(0,0,0,0.4);
  display: none;
}

.search-result-item {
  padding: 9px 14px;
  cursor: pointer;
  border-bottom: 1px solid var(--border-soft);
  transition: background 0.12s;
  display: flex;
  align-items: center;
  gap: 10px;
}
.search-result-item:last-child { border-bottom: none; }
.search-result-item:hover,
.search-result-item.focused  { background: var(--surface2); }

.search-result-item .result-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.search-result-item .result-text { flex: 1; min-width: 0; }

.search-result-item .type-tag {
  font-size: 0.62rem;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--muted);
  letter-spacing: 0.5px;
}

.search-result-item .result-label {
  font-size: 0.82rem;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.search-result-item .result-sub {
  font-size: 0.72rem;
  color: var(--muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ── Scrollbar ───────────────────────────────────────────────────────── */
::-webkit-scrollbar { width: 5px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--muted); }