$(this).css('background-color', 'red');

You actually got it. Just forgot some quotes.

$(this).css({backgroundColor: 'red'});

or

$(this).css('background-color', 'red');

You don't need to pass over a map/object to set only one property. You can just put pass it as string. Note that if passing an object you cannot use a -. All CSS properties which have such a character are mapped with capital letters.

Reference: .css()

How about this:

$(this).css('background-color', '#FFFFFF');

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