:root {
  --bg: #0f1216;
  --panel: #171b21;
  --panel2: #1d2229;
  --line: #2a3038;
  --text: #cfd8e3;
  --muted: #7c8a9a;
  --accent: #4fb0ff;
  --accent2: #f2c14e;
  --green: #53e08a;
  --red: #ff5a5a;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font: 13px/1.4 ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  display: flex; flex-direction: column; height: 100vh; overflow: hidden;
  user-select: none;
}

/* ---- top bar ---- */
#topbar {
  display: flex; align-items: center; gap: 14px;
  padding: 8px 12px; background: var(--panel); border-bottom: 1px solid var(--line);
  flex-wrap: wrap;
}
.brand { font-weight: 700; font-size: 15px; letter-spacing: .2px; color: #fff; }
.brand .sub { display: block; font-size: 10px; font-weight: 500; color: var(--muted); letter-spacing: .3px; }
.group { display: flex; align-items: center; gap: 6px; }
.group.right { margin-left: auto; }
.lbl { color: var(--muted); font-size: 11px; text-transform: uppercase; letter-spacing: .5px; margin-right: 2px; }

button {
  background: var(--panel2); color: var(--text); border: 1px solid var(--line);
  border-radius: 6px; padding: 6px 10px; cursor: pointer; font-size: 12px;
}
button:hover { border-color: #3a4655; background: #222833; }
button.active { border-color: var(--accent); color: #fff; box-shadow: inset 0 0 0 1px var(--accent); }
button.op { font-weight: 600; }
button.op.cut { color: #ffb3b3; }
#btn-auto.active { border-color: var(--green); color: #d6ffe6; box-shadow: inset 0 0 0 1px var(--green); }

.num { display: flex; align-items: center; gap: 4px; color: var(--muted); font-size: 11px; }
.num input {
  width: 58px; background: #0d1116; border: 1px solid var(--line); color: var(--text);
  border-radius: 5px; padding: 4px 6px; font-size: 12px;
}

/* keyboard-shortcut pills shown on buttons/labels */
kbd {
  display: inline-block; margin-left: 5px; padding: 1px 5px; min-width: 12px;
  font: 600 10px/1.5 ui-monospace, SFMono-Regular, Menlo, monospace;
  color: var(--muted); background: #0d1116; border: 1px solid var(--line);
  border-bottom-width: 2px; border-radius: 4px; text-align: center; vertical-align: middle;
}
button:hover kbd, button.active kbd { color: var(--text); border-color: #3a4655; }
.num kbd { margin-left: 6px; }

/* ---- main split ---- */
main { flex: 1; display: flex; min-height: 0; }

#tools {
  width: 74px; background: var(--panel); border-right: 1px solid var(--line);
  display: flex; flex-direction: column; gap: 4px; padding: 8px 6px; overflow-y: auto;
}
#tools button {
  display: flex; flex-direction: column; align-items: center; gap: 2px;
  padding: 7px 2px; background: transparent; border: 1px solid transparent;
}
#tools button b {
  display: inline-flex; width: 22px; height: 22px; align-items: center; justify-content: center;
  border: 1px solid var(--line); border-radius: 5px; font-size: 12px; color: var(--accent2);
}
#tools button span { font-size: 10px; color: var(--muted); }
#tools button:hover { border-color: var(--line); background: var(--panel2); }
#tools button.active { border-color: var(--accent); background: #1a2330; }
#tools button.active b { border-color: var(--accent); color: #fff; }
#tools hr { width: 80%; border: none; border-top: 1px solid var(--line); margin: 4px 0; }

.pane { position: relative; flex: 1; min-width: 0; overflow: hidden; }
.pane-label {
  position: absolute; top: 8px; left: 10px; z-index: 5;
  font-size: 10px; letter-spacing: .6px; text-transform: uppercase; color: var(--muted);
  background: rgba(10,13,17,.6); padding: 3px 7px; border-radius: 5px; pointer-events: none;
}
#sketch-canvas { width: 100%; height: 100%; display: block; cursor: crosshair; background: #0c0f13; }

/* per-tool contextual hint (bottom of the Sketch Pane) */
#sketch-hint {
  position: absolute; left: 10px; bottom: 10px; right: 10px; z-index: 5;
  display: flex; flex-wrap: wrap; align-items: center; gap: 6px 10px;
  font-size: 11px; color: var(--muted); pointer-events: none;
  background: rgba(10,13,17,.72); border: 1px solid var(--line);
  border-radius: 7px; padding: 6px 10px; backdrop-filter: blur(3px);
}
#sketch-hint .ht { color: var(--accent2); font-weight: 700; text-transform: uppercase; letter-spacing: .5px; }
#sketch-hint b { color: var(--text); font-weight: 600; }
#sketch-hint .sep { color: #3a4655; }
#viewport { width: 100%; height: 100%; }

#divider { width: 1px; background: var(--line); }

/* ---- status bar ---- */
#statusbar {
  display: flex; align-items: center; gap: 18px;
  padding: 6px 12px; background: var(--panel); border-top: 1px solid var(--line);
  font-size: 12px;
}
#status { color: var(--accent2); font-weight: 600; }
.hint { color: var(--muted); font-size: 11px; }
.hint b { color: var(--text); }

button.accent { border-color: var(--accent); color: #dff0ff; }
button.accent:hover { background: #1a2735; }

/* ---- ViewCube (Mesh Pane, top-right) ---- */
#view-cube {
  position: absolute; top: 10px; right: 10px; z-index: 6;
  cursor: default; filter: drop-shadow(0 4px 10px rgba(0,0,0,.45));
}

/* ---- on-screen camera controls (Mesh Pane) ---- */
#cam-controls {
  position: absolute; right: 12px; bottom: 12px; z-index: 6;
  display: flex; flex-direction: column; gap: 4px; width: 66px;
  background: rgba(16,20,26,.7); border: 1px solid var(--line);
  border-radius: 8px; padding: 6px; backdrop-filter: blur(3px);
}
#cam-controls button {
  padding: 5px 0; font-size: 11px; text-align: center; background: var(--panel2);
}
#cam-controls .cam-row { display: flex; gap: 4px; }
#cam-controls .cam-row button { flex: 1; padding: 5px 0; }

/* ---- tutorial panel ---- */
#tutorial {
  display: none; position: fixed; z-index: 50; left: 50%; bottom: 46px;
  transform: translateX(-50%); width: min(560px, 92vw);
  background: #171b21;
  border: 1px solid var(--accent); border-radius: 12px; padding: 16px 18px;
  box-shadow: 0 12px 40px rgba(0,0,0,.5);
}
#tutorial .tut-head { display: flex; align-items: center; justify-content: space-between; }
#tutorial .tut-prog { font-size: 11px; letter-spacing: .5px; text-transform: uppercase; color: var(--accent); font-weight: 700; }
#tutorial .tut-x { background: transparent; border: none; color: var(--muted); font-size: 14px; padding: 2px 6px; }
#tutorial .tut-x:hover { color: #fff; }
#tutorial .tut-title { margin: 6px 0 8px; font-size: 16px; color: #fff; }
#tutorial .tut-body { font-size: 13px; line-height: 1.55; color: var(--text); }
#tutorial .tut-body b { color: var(--accent2); font-weight: 600; }
#tutorial .tut-nav { display: flex; justify-content: flex-end; gap: 8px; margin-top: 14px; }
#tutorial .tut-nav button { padding: 7px 16px; }
#tutorial .tut-next { border-color: var(--accent); color: #fff; background: #1c3350; font-weight: 600; }
#tutorial .tut-back:disabled { opacity: .4; cursor: default; }

/* ---- tutorial highlight ---- */
.tut-highlight {
  outline: 2px solid var(--accent) !important; outline-offset: 2px;
  border-radius: 6px; animation: tutpulse 1.3s ease-in-out infinite;
}
@keyframes tutpulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(79,176,255,.55); }
  50% { box-shadow: 0 0 0 6px rgba(79,176,255,0); }
}