button {
    padding: 0;
    width: 100px;
    height: 100px;
    /* center */
    margin: 0 auto;
}

/* .constant-arrows {
    display: flex;
    flex-direction: row;
} */

.precision-arrows {
    display: flex;
    flex-direction: row;
}

.outputs {
    display: flex;
    flex-direction: column;
}

body {
    background-image: url("pie.gif");
    background-repeat: no-repeat;
    background-position: center;
    background-size: cover;
    background-attachment: fixed;
    background-color: #000000;
    color: rgb(0, 128, 255);
    font-family: "Courier New", Courier, monospace;
    font-size: 75px;
    text-align: center;
}

footer {
    font-size: 20px;
    position: absolute;
    bottom: 0;
    width: 100%;
    height: 2.5rem;
    color: maroon;
}

button > img {
    width: 100%;
    height: 100%;
}