title: Add minor gridlines to matplotlib plot using seaborn
body: <p>I'm a fan of the Seaborn package for making nice-looking plots using Matplotlib. But I can't seem to figure out how to show minor gridlines in my plots.</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  import seaborn as sbn
  
  x = np.linspace(0, 2 * np.pi, 100)
  y = np.sin(x)
  
  fig, ax = plt.subplots(1, 1)
  ax.scatter(x, y)
  
  ax.grid(b=True, which='major')
  ax.grid(b=True, which='minor')
  </code></pre>
  
  <p>gives:</p>
  
  <p><img src="https://i.stack.imgur.com/bi3kQ.png" alt="enter image description here"></p>
  
  <p>Any thoughts here?  Also any thoughts on how to adjust the style of the Seaborn gridlines that do show up...in particular, I'd love to make them narrower.</p>