feat(gui): add time GUI

Co-authored-by: Copilot <copilot@github.com>

css/style.css

@@ -15,6 +15,10 @@ canvas {
   display: block;
 }
 
+.canvas-stage {
+  position: relative;
+}
+
 .maze-layout {
   width: min(1100px, calc(100vw - 24px));
   margin: 12px auto 20px;
@@ -44,6 +48,36 @@ canvas {
   height: min(62vh, 680px);
 }
 
+.canvas-hud {
+  position: absolute;
+  top: 14px;
+  left: 14px;
+  z-index: 2;
+  padding: 10px 12px;
+  border-radius: 12px;
+  background: rgba(6, 10, 15, 0.72);
+  border: 1px solid rgba(121, 174, 242, 0.3);
+  backdrop-filter: blur(8px);
+  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.28);
+  pointer-events: none;
+}
+
+.canvas-hud-label {
+  font-size: 10px;
+  letter-spacing: 0.14em;
+  text-transform: uppercase;
+  color: #93a4b8;
+  margin-bottom: 4px;
+}
+
+.canvas-hud-value {
+  font-size: 22px;
+  font-weight: 700;
+  line-height: 1;
+  color: #eef5ff;
+  text-shadow: 0 0 12px rgba(121, 174, 242, 0.35);
+}
+
 .control-panel {
   padding: 16px;
   overflow-y: auto;

index.html

@@ -11,7 +11,13 @@
     <main class="maze-layout">
       <section class="panel">
         <div class="panel-label">Babylon Scene</div>
-        <canvas id="renderCanvas"></canvas>
+        <div class="canvas-stage">
+          <canvas id="renderCanvas"></canvas>
+          <div class="canvas-hud">
+            <div class="canvas-hud-label">Elapsed time</div>
+            <div id="canvas-time" class="canvas-hud-value">0.0s</div>
+          </div>
+        </div>
       </section>
 
       <section class="panel">
@@ -53,7 +59,7 @@
             <div class="status-display">
               <div class="status-line"><strong>Seed:</strong> <span id="status-seed">0</span></div>
               <div class="status-line"><strong>Level:</strong> <span id="status-level">1</span></div>
-              <div class="status-line"><strong>Time:</strong> <span id="status-time">0.0</span>s</div>
+              <div class="status-line"><strong>Time:</strong> <span id="status-time">0.0</span></div>
               <div class="status-line"><strong>Key:</strong> <span id="status-key">no</span></div>
               <div class="status-message" id="status-message">Adjust settings, then start a run.</div>
             </div>

src/babylon_setup.js

@@ -6,6 +6,7 @@ import { gridCellToWorld, isWalkableCell } from "./game/grid.js";
 // Initialize Babylon.js engine and scene
 const canvas = document.getElementById("renderCanvas");
 const engine = new BABYLON.Engine(canvas, true);
+const canvasTime = document.getElementById("canvas-time");
 
 const scene = new BABYLON.Scene(engine);
 scene.clearColor = new BABYLON.Color4(0.05, 0.07, 0.1, 1);
@@ -99,6 +100,9 @@ engine.runRenderLoop(() => {
     sphereMaterial.diffuseColor = sharedState.runtime.hasKey
         ? new BABYLON.Color3(0.25, 0.8, 0.45)
         : new BABYLON.Color3(0.2, 0.55, 0.95);
+    if (canvasTime) {
+        canvasTime.textContent = `${sharedState.runtime.elapsedSeconds.toFixed(1)}s`;
+    }
     scene.render();
 });
 
@@ -146,7 +150,8 @@ function buildLevelFromGrid(grid) {
     floor.position = new BABYLON.Vector3(0, 0, 0);
     floor.checkCollisions = true;
     const fm = new BABYLON.StandardMaterial('floorMat', scene);
-    fm.diffuseColor = new BABYLON.Color3(0.08, 0.08, 0.09);
+    fm.specularColor = new BABYLON.Color3(0.1, 0.1, 0.1);
+    fm.diffuseColor = new BABYLON.Color3(0.58, 0.58, 0.59);
     floor.material = fm;
     levelMeshes.push(floor);