#canvas {
    background-color: lightblue;
    display: grid;
    grid-template-rows: 1fr 1fr 1fr;
    grid-template-columns: 1fr 1fr 1fr 1fr;
}

.card {
    height: 200px;
    width: 200px;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 10px;
}

.card img {
    cursor: pointer;
}

.correct {
    border: 20px solid green;
}

.incorrect {
    border: 20px solid red;
}