No, spilling coffee is not "gross negligence," which goes beyond ordinary carelessness. Spilling coffee on a laptop is only ordinary or everyday carelessness.However, you are incorrect in that *anytime* you damage or destroy another's property through negligence, or carelessness, even ordinary carelessness, you can be held liable for the cost to repair or value of what you damaged or destroyed. The employer cannot simply withhold or deduct your pay unless you consented to the deduction, whether specifically for this case or as a general policy for damage. Instead, they were supposed to sue you for the money, like any person would sue someone who damaged their laptop.However, even though they should not have withheld pay, as a practical matter, there may be little you can do: if you sue for the money back, they could countersue or counterclaim in that case for the damage to their laptop, or even just interpose the damage you did and costs you caused them to incur as a "set-off" (or credit) against anything they owe you. If they took out an amount equal to or less than the laptop cost, it would net out against what they owe in terms of wages, assuming they can prove you were careless to spill the coffee and the coffee required replacement of the laptop; therefore, if you did damage or destroy their laptop, if you sued for the money they took out but they raised the issue of the laptop in return, you'd likely net out to more-or-less the same place. It may not be worthwhile trying to get the money back, since you may not come out ahead.