main {
    display: grid;
    grid-template-rows: auto auto auto auto;
    width: 100%;
    max-width: 400px;
    height: 100%;
    max-height: 600px;
    margin: auto;
}

section {
    display: grid;
    grid-template-columns: calc(100% / 3) calc(100% / 3) calc(100% / 3);
}

button {
    background-color: black;
    padding: 20px;
    font-size: 80px;
    color: white;
    font-family: 'Fira Code', monospace;
}

body {
    display: block;
    text-align: center;
    font-family: 'Open Sans', sans-serif;
}

h1, h2, h3, h4, h5, h6, p, ul, ol {
    margin: 0;
}