body {
    margin: 0;
    height: 100vh;
    display: grid;
    place-items: center;
    background-color: #18132e;
}
.app {
    /* border: 2px solid yellow; */
    width: 30%;
    display: grid;
    place-items: center;
    grid-template-columns: repeat(3, 1fr);
    gap: 1em;
}
.box {
    /* border: 2px solid rebeccapurple; */
    height: 100px;
    width: 100px;
    background-color: rgb(5,118,216);
    display: grid;
    place-items: center;
    font-size: 4.5em;
}

/* https://www.youtube.com/watch?v=mEv4BcbCFVU */