Material design: text color settings

I'm trying to follow Google material design guidelines. I use the same settings for text color but the text is hard to read because in the examples they have an almost white background.

http://ift.tt/1jiNe7j

The standard alpha value for text on a white background is 87% (#000000).

Secondary text, which is lower in the visual hierarchy, should have an alpha value of 54% (#000000).

Text hints for users, like those in text fields and labels, have an even lower visual prominence and should have an alpha value of 26% (#000000).

My background color is #efefef and the color of label text is black with 26% opacity so it's hard to read. Do you have any suggestion on how to adjust the color of text (maybe a general rule) so I can use this background.