Examples: Clean up. (#31623)

examples/tags.json

@@ -138,6 +138,7 @@
 	"webgpu_mirror": [ "reflection" ],
 	"webgpu_multiple_rendertargets": [ "mrt" ],
 	"webgpu_multiple_rendertargets_readback": [ "mrt" ],
+	"webgpu_particles": [ "fire" ],
 	"webgpu_postprocessing_3dlut": [ "color grading" ],
 	"webgpu_postprocessing_afterimage": [ "trails" ],
 	"webgpu_postprocessing_ao": [ "ambient occlusion", "mrt" ],

examples/webgpu_particles.html

@@ -53,6 +53,7 @@
 				camera.position.set( 1300, 500, 0 );
 
 				scene = new THREE.Scene();
+				scene.background = new THREE.Color( 0x333333 );
 
 				// textures
 
@@ -133,7 +134,7 @@
 
 				//
 
-				const helper = new THREE.GridHelper( 3000, 40, 0x303030, 0x303030 );
+				const helper = new THREE.GridHelper( 3000, 40, 0x444444, 0x444444 );
 				helper.position.y = - 75;
 				scene.add( helper );