Though it\'s debatable, I\'ve heard the majority of CSS developers prefer multi-line because of the ease of which a property can be found within the CSS file. But doesn\'t this
IMO multi-line CSS is better because its more readable. But i would suggest you to follow your teams's standard and dont waste your time debating :)
And if you are worried about CSS file size, then you should minify / compress it.
Also, if you have time, you spend some on validating your CSS using Official W3C CSS Test Suites.