Code-blocks with line nos - lines and line numbers don't line up.

[TonyFlury]

Using the rtd Theme with this source :

.. code-block:: python
    :linenos:

    import tkinter as tk
    root = tk.Tk()
    w = tk.Label(root, text='Hello, world!')
    w.pack()
    root.mainloop()

The resultant rendered page has this :

[TonyFlury]

It seems to be that the line nos are rendered with a line height of 1.5 - and generated html seems to also state the same line height value for the code, but there seems to be a clash between the line heights set in the theme :

These two CSS rules get appled to the code block

.rst-content .highlight > pre {
line-height: normal;
}

and :

 div[class^="highlight"] pre {
         ....
     line-height: 1.5;
        ....
 }

but the line-height: normal; takes precedence; changing the line-height value in the first rule results in correctly aligining line nos and code.

[Blendify]

This is a duplicate of #417