* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
.calculator {
    width: 600px;
    margin: 100px auto;
}
input {
    width: 100%;
    height: 50px;
    font-size: 25px;
}
.buttons {
    width: 100%;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 20px;
    padding-top: 20px;
}
button {
    width: 130px;
    height: 50px;
}

@keyframes horizontal-shaking {
 0% { transform: translateX(0) }
 10% { transform: translateX(5px) }
 20% { transform: translateX(-5px) }
 30% { transform: translateX(5px) }
 40% { transform: translateX(0) }
 50% { transform: translateX(-5px) }
 60% { transform: translateX(5px) }
 70% { transform: translateX(-5px) }
 80% { transform: translateX(0px) }
 90% { transform: translateX(-5px) }
 100% { transform: translateX(0) }
}