The translation of Chinese into English in China is an ever-present problem that I noticed while living on the mainland. Also, many Chinese and expatriate friends alike would bring the 'interesting' stories to my attention. So, according to the media in mainland China right now the slogan for Mengniu (I actually like that brand) is “只为点滴幸福”. Now, if we analyse the characters used here it's a bit clever "点滴"; the company sells milk so the use of 'drop' (of liquid) which is alluding to their milk product is cute, haha. One could translate this into "Every drop of happiness matters". This is a clever slogan, but using the incorrect translation should be quite embarrassing for this well-known brand. They should listen to experts. ^_^

I'd write it as "a little happiness matters" or "little happinesses matter". The second sentence is a little odd, but that may be the right thing for an advertising campaign.

It's possible the slogan means that if you're even a little happy, then that's all that matters. Meaning, you don't have to be overjoyed all day every day. Probably I would have added an A at the beginning so that it read "A little happiness matters"