Home hair color has always had its pros and cons — it's cheaper than the salon, but it's always reminded us a little too much of chemistry class with the mixing and shaking and ability to get things wrong. But L'Oréal Paris is working to change that with its latest launch of Mousse Absolue. It combines both the dye and the developer in one bottle (if you turn the bottle upside down, you can see the two chambers). Click the button, and the right proportion of both formulas comes out in an easy-to-apply foam. If you don't use the whole bottle up on your first application, no worries. And since the dye and the developer are kept separate until the moment you press the button, you can reuse for root touch-ups or stray gray hairs. One fan of the new product is style blogger extraordinaire Garance Doré, who created a charming video (below) to show how she uses it.