@sarah2r,
You should set a reduced height:
fig = go.Figure(go.Table(header=dict(values=['A Scores', 'B Scores']),
cells=dict(values=[[100, 90, 80, 90], [95, 85, 75, 95]]))
);
fig.update_layout(title_text='My Table', title_x=0.5,
width=600, height=200,
margin=dict(t=50, r=2, b=2, l=2))