add primary variant to Generate button and fix import spacing

app.py

@@ -9,6 +9,7 @@ import torch.nn.functional as F
 
 from rendering import estimate_surface_normal
 
+
 DESCRIPTION = """
 <div class="head">
 <div class="title">LiDAR Data Synthesis with Denoising Diffusion Probabilistic Models</div>
@@ -169,7 +170,7 @@ with gr.Blocks() as demo:
                 value=32,
                 label="Number of sampling steps (>256 is recommended)",
             )
-            btn = gr.Button(value="Generate")
+            btn = gr.Button(value="Generate", variant="primary")
 
         with gr.Column():
             range_view = gr.Image(type="numpy", label="Range image")