Pygments Alabaster code block style background color

[ClodoaldoPinto]

I'm using the Alabaster theme and I want to change the Pygments style for the code blocks. To do so I changed the pygments_style in conf.py:

pygments_style = 'monokai'

And it changes the font's properties but not the background color.
I tried adding a custom.css file to _static:

div.viewcode-block:target {
    background: #00d;
}

But the background does not change. What am I missing?

[ClodoaldoPinto]

I got it: custom.css:

dt:target, .highlight {
    background: #002;
}