Melrose Avenue and recruited artist Chris Bilheimer, who had designed the art for the previous records Nimrod and International Superhits! to create the cover. The band aimed for the cover to be "at once uniform and powerful". The album's artwork—"a Posada-stark print of a heart-shaped hand grenade gripped in a blood-soaked fist"—is representative of its political content. After listening to the new music on his computer, Bilheimer took note of the lyric "And she's holding on my heart like a hand grenade" from "She's a Rebel". Influenced by artist Saul Bass's poster for the 1955 drama film The Man with the Golden Arm, Bilheimer created an upstretched arm holding a red heart-shaped grenade. Although he felt that red is the "most overused color in graphic design", he felt that the "immediate" qualities of the color deemed it appropriate for use on the cover. He explained, "I'm sure there's psychological theories of it being the same color of blood and therefore has the powers of life and death... And as a designer I always feel it's kind of a cop-out, so I never used it before. But there was no way you couldn't use it on this cover." The band also underwent "a significant image change," and they began wearing black and red uniforms onstage. Armstrong considered it a natural extension of his showmanship, which began in his childhood. Critical reception American Idiot received generally positive reviews from music critics. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream publications, the album received an average score of 79, based on 26 reviews. According to AllMusic, it earned Green Day "easily the best reviewed album of their career." The website's editor Stephen Thomas Erlewine praised the album as either "a collection of great songs" or as a whole, writing that, "in its musical muscle and sweeping, politically charged narrative, it's something of a masterpiece". Pitchfork deemed it "ambitious" and successful in getting across its message, while "keep[ing] its mood and method deliberately, tenaciously, and angrily on point". NME characterized it as "an onslaught of varied and marvellously good tunes presented in an unexpectedly inventive way." Q called the album "a powerful work, noble in both intent and execution." The New York Times commended Green Day for trumping "any pretension with melody and sheer fervor". Chicago Sun-Times critic Jim DeRogatis wrote that the band had successfully "hit upon