Theme: customizing built-in styles lke .item-ios-light

I am customizing my upcoming app.
I set the colors in variables.scss as documentation requires.
I changed some sass variables.
This takes me 80% down the road. But I have stumbled with this.
I want to customize some ion-items. I want them to have color(colors, light) background and color(colors, dark) foreground color.
And yet, there seem to not be variables that allow to do that.
Looking at node_modules\ionic-angular\css\ionic.css, one finds that the stile bearing standard palette color name does not take the value of that color
line 7447

.item-divider-ios-light {
  color: #000;
  background-color: #f4f4f4; }

so I could have redefined the class in variables.scss, or create my own class, but that, IMHO, would go against the grain of ionic. What would you suggest I do?