Hollywood darlings and PTYs stepped out to the Mondrian last night to celebrate the season at the 12th Annual InStyle Summer Soiree, and they made sure to dress the part. The poolside bash was filled with starlets in bold colors, crisp whites and on-trend cuts and shapes that made for fabulous summer evening party attire. See our picks for the event's Best Dressed Guests in these top six looks of the night. [Photos via, via]