Yet another try.

app.py

@@ -372,7 +372,8 @@ if len(args) > 0:
 
 
 # ====== Create GUI =========================================================
-with gradio.Blocks(css = css, theme = gradio.themes.Glass(secondary_hue=gradio.themes.colors.blue), fill_height = False, fill_width = True) as gui:
+with gradio.Blocks(css = css, theme = gradio.themes.Glass(secondary_hue=gradio.themes.colors.blue),
+                   fill_height = False, fill_width = True) as gui:
 
    # ====== Session handling ================================================
    # Session initialization, to be called when page is loaded
@@ -381,7 +382,7 @@ with gradio.Blocks(css = css, theme = gradio.themes.Glass(secondary_hue=gradio.t
    gui.unload(cleanUpSession)
 
    # ====== Header ==========================================================
-   with gradio.Row(scale = 0):
+   with gradio.Row(height = '10vh', min_height = '10vh', max_height = '10vh'):
       big_block = gradio.HTML("""
 <div class="program-header">
    <div class="program-logo-left">
@@ -395,7 +396,7 @@ with gradio.Blocks(css = css, theme = gradio.themes.Glass(secondary_hue=gradio.t
 """)
 
    gradio.Markdown('## Settings')
-   with gradio.Row():
+   with gradio.Row(height = '10vh', min_height = '10vh', max_height = '10vh'):
       sliderNumberOfECGs     = gradio.Slider(1, 100, label="Number of ECGs", step = 1, value = 4, interactive = True)
       # sliderLengthInSeconds = gradio.Slider(5, 60, label="Length (s)", step = 5, value = 10, interactive = True)
       dropdownType           = gradio.Dropdown( [ 'ECG-12', 'ECG-8' ], label = 'ECG Type', interactive = True)
@@ -415,17 +416,19 @@ with gradio.Blocks(css = css, theme = gradio.themes.Glass(secondary_hue=gradio.t
 
       # with gradio.Row():
 
-   analysisOutput = gradio.Plot()
-
-   outputGallery = gradio.Gallery(label         = 'output',
-                                  columns       = 4,
-                                  rows          = 1,
-                                  height        = '5hv',
-                                  object_fit    = 'contain',
-                                  show_label    = True,
-                                  allow_preview = True,
-                                  preview       = False
-                                 )
+   with gradio.Row(height = '32vh', min_height = '32vh', max_height = '32vh'):
+      analysisOutput = gradio.Plot()
+
+   with gradio.Row(height = '24vh', min_height = '24vh', max_height = '24vh'):
+      outputGallery = gradio.Gallery(label         = 'output',
+                                    columns       = 8,
+                                    rows          = 1,
+                                    height        = 'auto',
+                                    object_fit    = 'contain',
+                                    show_label    = True,
+                                    allow_preview = True,
+                                    preview       = False
+                                    )
    outputGallery.select(select)