[css] Why can't I use background image and color together?

To tint an image, you can use CSS3 background to stack images and a linear-gradient. In the example below, I use a linear-gradient with no actual gradient. The browser treats gradients as images (I think it actually generates a bitmap and overlays it) and thus, is actually stacking multiple images.

background: linear-gradient(0deg, rgba(2,173,231,0.5), rgba(2,173,231,0.5)), url(images/mba-grid-5px-bg.png) repeat;

Will yield a graph-paper with light blue tint, if you had the png. Note that the stacking order might work in reverse to your mental model, with the first item being on top.

Excellent documentation by Mozilla, here:

https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Using_multiple_backgrounds

Tool for building the gradients:

http://www.colorzilla.com/gradient-editor/

Note - doesn't work in IE11! I'll post an update when I find out why, since its supposed to.