"I'll say it again: "less" is amount, "fewer" is number"
LESS applies to singular nouns ("less tonic water in my gin & tonic, please!") or units of measure ("less than an ounce of tequila in my shot? Highway robbery!").
FEWER applies to plural nouns ("fewer drinkers at the bar than we expected") or number of things ("10 items or fewer").
There are a few exceptions such as with time & money ("less than a dollar a day!"), but generally, just remember that fewer refers to numbers and I'll be happy.
~ ~ ~ All meetings end in separation All acquisition ends in dispersion All life ends in death - The Buddha