Rails PDF is not accepting CSS

Hi,

  I am not able to see the css inside the PDF. the generated pdf will
display in black n white. Am getting images inside the pdf file. Please
see the below code that i have implemented. If anyone finds a solution
please help!

Am using
OS :Ubuntu
Rails: 4.1.8
Ruby :2.1.5p273
Webserver: Unicorn
pdfkit version : 0.6.2

these are my code

initializers/pdfkit.rb