styles.css

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

body {
    max-height: 100dvh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 0;
}

button {
    padding: 1rem;
    font-size: larger;
    font-weight: 700;
    background: linear-gradient(22deg, rgba(168, 72, 172, 0.848), purple);
    color: white;
    border-radius: 2px;
}
span {
    font-weight: 800;
    font-size: larger;
    padding: 1rem;
}
main {
    flex: 1 1 auto;
    flex-direction: column;
    border: 3px double purple;
    display: flex;
    justify-content: center;
    align-items: center;
    aspect-ratio: 1;
    gap: 0;
}

main > div {
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 0 0 auto;
    width: 660px;
}

main div div {
    flex: 1 1 auto;
    aspect-ratio: 1;
    border: 1px solid black;
}

@media only screen and (max-width: 400) {
    main > div {
        flex: 1 1 auto;
        width: 320px;
        max-width: 320px;
        height: 15px
    }
    main {
        height: 90dvh;
        max-width: 94vw;
    }
    body {
        height: 90dvh;
        max-width: 100vw;
    }
}