*,*:after,*:before{box-sizing: border-box}body{font-family: "Press Start 2P", cursive;background-image: linear-gradient(120deg, #fdfbfb 0%, #ebedee 100%);background-repeat: no-repeat;height: 100vh;width: 100vw;position: fixed;top: 0;left: 0;display: flex;justify-content: center;align-items: center}h2{text-align: center;font-size: 1em}#calculator{width: 310px;height: 510px;margin: 10px auto;overflow: hidden;text-align: center;background-color: #871f37;box-shadow: 0 2px 2px rgba(0, 0, 0, 1.2)}.contenedor{height: 60px;overflow: hidden}#operation{font-size: 20px;color: #000;background-color: #f5ed93;text-align: right;height: 100%}#screen{font-size: 8px;border: 0;color: rgb(34, 32, 32);background-color: #dfd3ba;text-align: right;width: 230px;overflow: hidden;margin-bottom: 0}#teclado{background-color: #7d7c7c;height: 320px}.nes-btn{width: 50px;height: 40px;float: left;transition: all 0.8s}.is-error{width: 108px}p{text-align: center;font-size: 12px;padding-top: 10px;color: #ddd}footer{padding: 8px 0 0 0;text-align: center}footer i{padding: 0 20px}