*,
*::after,
*::before {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

body {
    background-color: grey;
    display: grid;
    align-items: center;
    justify-items: center;
    height: 100vh;
    width: 100vw;
    font-family: Helvetica, Arial, sans-serif;
    text-align: center;
}

.game-board {
    height: 100vmin;
    width: 100vmin;
    background-color: white;
    display: grid;
    grid-template-rows: repeat(21, 1fr);
    grid-template-columns: repeat(21, 1fr);
}

.snake {
    background-color: lightgreen;
    border: .25vmin solid black;
}

.food {
    background-color: orangered;
    border: .25vmin solid black;
}

.mobile-arrow-buttons {
    position: fixed;
    bottom: 12.5px;
    width: 50%;
    height: 100px;
    display: none;
}
.button {
    width: 33.33333333%;
    height: 50%; 
    background-color: grey;
    float: left;
    display: grid;
    align-items: center;
    justify-items: center;
    border: .75px solid white;
    border-radius: 15px;
    font-size: 20px;
}
.button--up {
    width: 100%;
}

@media only screen and (max-width: 400px) {
    .mobile-arrow-buttons {
        display: block;
    }
}