main.css

.area-wrapper {
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}
h1{
    text-align: center;
    font-size: 62px;
    color: rgb(1, 18, 255);
}

#area {
    border: black 2px solid;
    width: 600px;
    height: 600px;
    background-color: rgb(173, 251, 253);
    display: flex;
    flex-wrap: wrap;
}

.box {
    width: 200px;
    height: 200px;
    border: 1px solid black;
    box-sizing: border-box;
    font-size: 84px;
    color: brown;
    display: flex;
    justify-content: center;
    align-items: center;
}

#modal-result-wrapper {
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    display: none;
}

#overlay {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    background-color: rgba(0,0,0,0.8);
}

#modal-window {
    width: 250px;
    height: 150px;
    border: 1px solid black;
    background-color: white;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    display: flex;
    font-size: 24px;
    flex-flow: column;
    justify-content: space-between;
    align-items: center;
}

#btn-close {
    width: 250px;
    height: 50px;
    background-color: tomato;
    color: teal;
    text-align: center;
    cursor: pointer;
    padding-top: 25px;
}
#content{
    padding-top: 25px;
}