https://www.kristinesshair.com/products/winter-wheat

I just used this and it did help with the toning (a bit messy though).

Do you only highlight your hair or do you also color it? If you are simply highlighting, then you can buy either a toner or demi-permanent hair color (+ developer for both) and apply to your whole head. I can't really speak to what color to recommend without knowing what type of "light brown" your hair is.

If you have a double-process color, then you could apply a version of your natural color to your roots and then apply a toner over that.

Any time I (used to) get my hair highlighted at the salon, they would follow it with an all-over toner. Where do I buy that? I have light brown hair and most of my highlights have grown out. I have some grays and would like to get a light blond toner that will cover the gray but not lighten (turn brassy) my light brown. (no peroxide or ammonia). Can any stylists help point me in the direction of what to buy?

Thanks!