body {
    margin: 0;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: black;
}

.pi {
    width: 30em;
    height: 30em;
    font-size: 12px;
    display: grid;
    grid-template-columns: repeat(10, 1fr);
    grid-gap: 0.2em;
}

.pi span {
    --c: hsl(calc(var(--d) * 360 / 10), 40%, 40%);
    color: var(--c);
    font-size: 1.3em;
    background-color: var(--c);
    font-family: sans-serif;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    user-select: none;
    transition: 0.3s;
}

.pi span.show,
.pi span:hover {
    background-color: white;
    color: black;
    box-shadow: 0 0 1em yellow;
}