/* ═══════════════════════════════════════════════════════════════════════
   AVL Tree Visualizer  —  style.css
   Font: JetBrains Mono (monospace) + Space Grotesk (UI labels)
   ═══════════════════════════════════════════════════════════════════════ */

/* ── CSS Variables — Night Theme (default) ──────────────────────────── */
:root {
  --bg:          #0d0f17;
  --panel:       #141826;
  --panel-edge:  #2a344e;
  --accent:      #5aa0ff;
  --accent2:     #ff913c;
  --success:     #48d782;
  --danger:      #ff4b4b;
  --text-main:   #e4e9ff;
  --text-dim:    #697698;
  --edge-col:    #485478;
  --radius:      8px;
  --panel-w:     300px;
}

body.light {
  --bg:         #f0f3fc;
  --panel:      #ffffff;
  --panel-edge: #c3cde1;
  --accent:     #2d6ee6;
  --accent2:    #d26414;
  --success:    #1ea05a;
  --danger:     #d22d2d;
  --text-main:  #161c32;
  --text-dim:   #78829b;
  --edge-col:   #8291af;
}

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

html, body {
  height: 100%;
  overflow: hidden;
  font-family: 'Space Grotesk', sans-serif;
  background: var(--bg);
  color: var(--text-main);
  transition: background .25s, color .25s;
}

/* ── Layout ──────────────────────────────────────────────────────────── */
body {
  display: flex;
  height: 100vh;
}

#panel {
  width: var(--panel-w);
  min-width: var(--panel-w);
  height: 100vh;
  background: var(--panel);
  border-right: 2px solid var(--panel-edge);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 0;
  position: relative;
  flex-shrink: 0;
  /* Gradient accent bar at top */
  background-image: linear-gradient(to bottom, color-mix(in srgb, var(--accent) 70%, transparent) 0px, transparent 5px);
  transition: background .25s, border-color .25s;
}

/* Slim scrollbar */
#panel::-webkit-scrollbar { width: 4px; }
#panel::-webkit-scrollbar-thumb { background: var(--panel-edge); border-radius: 4px; }

#canvas-wrap {
  flex: 1;
  position: relative;
  overflow: hidden;
  background: var(--bg);
  transition: background .25s;
}

#tree-canvas {
  display: block;
  width: 100%;
  height: 100%;
  cursor: grab;
}
#tree-canvas:active { cursor: grabbing; }

/* ── Panel title ─────────────────────────────────────────────────────── */
.panel-title {
  padding: 16px 18px 10px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.title-main   { font-family: 'JetBrains Mono', monospace; font-size: 28px; font-weight: 700; color: var(--accent); line-height: 1.1; }
.title-sub    { font-size: 16px; font-weight: 600; color: color-mix(in srgb, var(--text-main) 55%, transparent); }
.title-edition{ font-size: 11px; color: color-mix(in srgb, var(--text-dim) 80%, transparent); letter-spacing: .05em; }

/* ── Theme toggle ────────────────────────────────────────────────────── */
.btn-theme {
  margin: 0 18px 4px;
  padding: 7px 12px;
  border-radius: 6px;
  border: 1px solid color-mix(in srgb, var(--accent) 40%, transparent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  color: var(--accent);
  font-family: 'Space Grotesk', sans-serif;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s, border-color .15s;
  text-align: left;
  letter-spacing: .03em;
}
body.light .btn-theme {
  border-color: color-mix(in srgb, #3c64dc 40%, transparent);
  background: color-mix(in srgb, #3c64dc 10%, transparent);
  color: #3c64dc;
}
.btn-theme:hover { background: color-mix(in srgb, var(--accent) 22%, transparent); }

/* ── Divider ─────────────────────────────────────────────────────────── */
.divider {
  border: none;
  border-top: 1px solid color-mix(in srgb, var(--panel-edge) 65%, transparent);
  margin: 6px 18px;
}

/* ── Sections ────────────────────────────────────────────────────────── */
.section {
  padding: 6px 18px 8px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.section-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .12em;
  color: var(--text-dim);
  padding-left: 8px;
  border-left: 3px solid var(--accent);
  margin-bottom: 2px;
}

/* ── Inputs ──────────────────────────────────────────────────────────── */
.input-row { display: flex; }

#val-input {
  width: 100%;
  padding: 10px 14px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 20px;
  font-weight: 700;
  text-align: center;
  background: color-mix(in srgb, var(--accent) 8%, transparent);
  border: 1.5px solid var(--panel-edge);
  border-radius: var(--radius);
  color: var(--text-main);
  outline: none;
  transition: border-color .15s, background .15s;
  caret-color: var(--accent);
}
#val-input:focus {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 14%, transparent);
}

.tip-text {
  font-size: 11px;
  color: color-mix(in srgb, var(--text-dim) 70%, transparent);
  padding-left: 2px;
}
kbd {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  background: color-mix(in srgb, var(--text-dim) 20%, transparent);
  border: 1px solid var(--panel-edge);
  border-radius: 3px;
  padding: 0 4px;
}

.gen-row {
  display: flex;
  align-items: center;
  gap: 8px;
}
.gen-row label { font-size: 15px; color: var(--text-dim); font-weight: 600; }
#rand-input {
  width: 64px;
  padding: 7px 10px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 15px;
  font-weight: 700;
  text-align: center;
  background: color-mix(in srgb, var(--text-dim) 8%, transparent);
  border: 1.5px solid var(--panel-edge);
  border-radius: var(--radius);
  color: var(--text-main);
  outline: none;
  transition: border-color .15s;
}
#rand-input:focus { border-color: var(--success); }
#rand-input::-webkit-inner-spin-button,
#rand-input::-webkit-outer-spin-button { -webkit-appearance: none; }

/* ── Buttons ─────────────────────────────────────────────────────────── */
.btn {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid transparent;
  border-radius: var(--radius);
  font-family: 'Space Grotesk', sans-serif;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  transition: background .15s, border-color .15s, transform .08s;
  letter-spacing: .02em;
}
.btn:active { transform: scale(.97); }
.btn.sm { padding: 9px 12px; font-size: 14px; }

.btn-accent {
  background: color-mix(in srgb, var(--accent) 18%, transparent);
  border-color: color-mix(in srgb, var(--accent) 35%, transparent);
  color: var(--accent);
}
.btn-accent:hover { background: color-mix(in srgb, var(--accent) 34%, transparent); }

.btn-danger {
  background: color-mix(in srgb, var(--danger) 15%, transparent);
  border-color: color-mix(in srgb, var(--danger) 30%, transparent);
  color: var(--danger);
}
.btn-danger:hover { background: color-mix(in srgb, var(--danger) 30%, transparent); }

.btn-danger-dim {
  background: color-mix(in srgb, #320c0c 90%, transparent);
  border-color: color-mix(in srgb, var(--danger) 22%, transparent);
  color: color-mix(in srgb, var(--danger) 80%, transparent);
}
.btn-danger-dim:hover { background: color-mix(in srgb, var(--danger) 22%, transparent); }

.btn-orange-dim {
  background: color-mix(in srgb, var(--accent2) 15%, transparent);
  border-color: color-mix(in srgb, var(--accent2) 30%, transparent);
  color: var(--accent2);
}
.btn-orange-dim:hover { background: color-mix(in srgb, var(--accent2) 30%, transparent); }

.btn-ghost {
  background: color-mix(in srgb, var(--panel-edge) 25%, transparent);
  border-color: color-mix(in srgb, var(--panel-edge) 40%, transparent);
  color: var(--text-main);
}
.btn-ghost:hover {
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  border-color: color-mix(in srgb, var(--accent) 25%, transparent);
}

.btn-green {
  background: color-mix(in srgb, var(--success) 20%, transparent);
  border-color: color-mix(in srgb, var(--success) 40%, transparent);
  color: var(--success);
  flex: 1;
}
.btn-green:hover { background: color-mix(in srgb, var(--success) 36%, transparent); }

.btn-row-2 { display: flex; gap: 6px; }
.btn-row-2 .btn { width: 50%; }

/* ── Speed buttons ───────────────────────────────────────────────────── */
.speed-row { display: flex; gap: 6px; }
.speed-btn {
  flex: 1;
  padding: 9px 4px;
  border-radius: var(--radius);
  border: 1.5px solid transparent;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  transition: background .15s, border-color .15s;
}
.speed-btn:nth-child(1) { background: color-mix(in srgb,#37b46e 10%,transparent); color: #37b46e; border-color: transparent; }
.speed-btn:nth-child(2) { background: color-mix(in srgb,#5aa0ff 10%,transparent); color: #5aa0ff; border-color: transparent; }
.speed-btn:nth-child(3) { background: color-mix(in srgb,#ff8c37 10%,transparent); color: #ff8c37; border-color: transparent; }

.speed-btn.active:nth-child(1) { background: color-mix(in srgb,#37b46e 52%,transparent); border-color: #37b46e; color: #fff; }
.speed-btn.active:nth-child(2) { background: color-mix(in srgb,#5aa0ff 52%,transparent); border-color: #5aa0ff; color: #fff; }
.speed-btn.active:nth-child(3) { background: color-mix(in srgb,#ff8c37 52%,transparent); border-color: #ff8c37; color: #fff; }

.speed-btn:hover { filter: brightness(1.25); }

/* ── Status bar ──────────────────────────────────────────────────────── */
#status-bar {
  margin-top: auto;
  width: 100%;
  background: color-mix(in srgb, var(--bg) 97%, transparent);
  border-top: 1px solid var(--panel-edge);
  padding: 10px 18px 14px;
}
body.light #status-bar { background: color-mix(in srgb, #d2d7e6 97%, transparent); }

.status-title { font-size: 11px; font-weight: 700; letter-spacing: .1em; color: var(--text-dim); margin-bottom: 4px; font-family: 'JetBrains Mono', monospace; }
.stat-line1   { font-size: 15px; font-weight: 700; color: var(--accent); min-height: 20px; }
.stat-line2   { font-size: 12px; color: var(--text-main); margin-top: 3px; min-height: 16px; line-height: 1.4; }

/* ── Canvas overlays ─────────────────────────────────────────────────── */

/* Live stats */
#live-stats {
  position: absolute;
  top: 14px;
  right: 14px;
  background: color-mix(in srgb, var(--panel) 94%, transparent);
  border: 1.5px solid var(--panel-edge);
  border-top: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 12px 16px 10px;
  min-width: 170px;
  backdrop-filter: blur(6px);
}
body.light #live-stats {
  background: color-mix(in srgb, #e6e9f5 98%, transparent);
  border-color: #96a1bf;
}
.ls-label  { font-family: 'JetBrains Mono', monospace; font-size: 11px; font-weight: 700; letter-spacing: .1em; color: var(--text-dim); margin-bottom: 6px; }
#ls-nodes,
#ls-height { font-family: 'JetBrains Mono', monospace; font-size: 17px; font-weight: 700; color: var(--text-main); line-height: 1.55; }
#ls-balance { font-size: 13px; font-weight: 700; margin-top: 4px; }
.ls-balanced { color: var(--success); }
.ls-unbalanced { color: var(--danger); }

/* Depth legend */
#depth-legend {
  position: absolute;
  top: 14px;
  left: 14px;
  display: flex;
  align-items: center;
  gap: 5px;
  background: color-mix(in srgb, #141828 80%, transparent);
  border-radius: 20px;
  padding: 5px 12px 5px 10px;
  backdrop-filter: blur(4px);
}
body.light #depth-legend { background: color-mix(in srgb, #c8cde2 90%, transparent); }
.legend-label { font-size: 12px; color: var(--text-dim); font-weight: 600; margin-right: 4px; }
.legend-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  flex-shrink: 0;
}

/* Hints bar */
#hints {
  position: absolute;
  bottom: 10px;
  left: 14px;
  font-size: 11px;
  color: color-mix(in srgb, var(--text-dim) 85%, transparent);
  background: color-mix(in srgb, #0a0c16 75%, transparent);
  border-radius: 20px;
  padding: 4px 14px;
  backdrop-filter: blur(4px);
}
body.light #hints { background: color-mix(in srgb, #c8cde2 88%, transparent); }

/* Traversal bar */
#trav-bar {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: color-mix(in srgb, var(--bg) 97%, transparent);
  border-top: 1px solid var(--panel-edge);
  padding: 8px 18px 10px;
  display: flex;
  gap: 10px;
  align-items: baseline;
  flex-wrap: wrap;
}
body.light #trav-bar { background: color-mix(in srgb, #d7dbe9 97%, transparent); }
#trav-title  { font-family: 'JetBrains Mono', monospace; font-size: 14px; font-weight: 700; color: var(--text-dim); white-space: nowrap; }
#trav-result { font-family: 'JetBrains Mono', monospace; font-size: 14px; font-weight: 600; color: var(--accent); word-break: break-all; }

/* Popup toast */
#popup {
  position: absolute;
  top: 54px;   /* sit below the depth-legend pill (≈14px top + 26px height + 14px gap) */
  left: 50%;
  transform: translateX(-50%);
  min-width: 260px;
  max-width: 520px;
  background: color-mix(in srgb, #0c101c 96%, transparent);
  border: 1.5px solid var(--popup-border, var(--accent));
  border-radius: 12px;
  padding: 12px 20px 16px;
  text-align: center;
  pointer-events: none;
  backdrop-filter: blur(8px);
  z-index: 100;
}
body.light #popup { background: color-mix(in srgb, #dce0ee 96%, transparent); }

#popup-msg {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 15px;
  font-weight: 600;
  color: var(--text-main);
  display: block;
  margin-bottom: 6px;
}
#popup-progress {
  height: 3px;
  border-radius: 2px;
  background: var(--popup-border, var(--accent));
  opacity: .6;
  transition: width .1s linear;
}

/* ── Responsive ───────────────────────────────────────────────────────── */
@media (max-width: 640px) {
  :root { --panel-w: 240px; }
  .title-main { font-size: 22px; }
  .btn        { font-size: 13px; }
}