Section 2.8 in Till Tantau's manual for TikZ tells me that I can manage styles - predefined sets of options that can be used to organize how a graphic is drawn.
I am trying to set my grid to be in red by manipulating help lines:
- the s at the end of help lines was missing
- the style has to be set in the tikzpicture options, in the square brackets (but can be set globally via \tikzstyle too)