Marissa Mayer making a late call on e-mail colorsMonths into her tenure, she was meeting with Sharma’s team regularly in a conference room that started to look more like a design studio: projectors hung from the ceiling, rendering screens displayed on the wall. All around, dozens of foam core boards were pinned with ideas. Mayer would regularly interrogate designers about the minutest details of display and user experience. By early December, one day before Yahoo Mail was set to release, she convened a meeting at Phish Food, a conference room in the executive building of Yahoo’s campus, to talk about the product’s color. For months, the team had settled on blue and gray. If users were going to read emails on their phones all day long, the thinking went, it was best to choose the most subtly contrasting hues. But now, Mayer explained, she wanted to change the colors to various shades of purple, which she believed better suited Yahoo’s brand.Some around the table were encouraged that their C.E.O. refused to release a product that she was less than fully satisfied with. If changing a few pixels led to an increase of 0.01 percent more users, that could translate to millions of dollars in ad revenue. Others, however, were visibly furious. According to one senior executive, Sharma’s body language changed the moment Mayer issued her request. He looked deflated. Altering the color of such an intricate product would require that members of his team spend all night adjusting colors in thousands of places. He slumped off and prepared to tell his staff the bad news.