* {
    box-sizing: border-box;
}
body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #fff;
    text-align: center;
}
h1 {
    font-size: 48px;
    color: orange;
    font-weight: bold;
    margin: 20px 0;
}
#grid {
    position: relative;
    display: grid;
    grid-template-columns: repeat(100, 16px);
    grid-template-rows: repeat(100, 16px);
    width: 1600px;
    height: 1600px;
    margin: 0 auto;
}
.square {
    width: 16px;
    height: 16px;
    transition: transform 0.2s;
}
.square:hover {
    transform: scale(1.5);
    z-index: 1;
}
.popup {
    position: absolute;
    background: white;
    border: 1px solid black;
    padding: 10px;
    display: none;
    width: 300px;
    z-index: 1000;
}
.popup img {
    width: 250px;
    height: 250px;
}
footer {
    margin-top: 30px;
    font-weight: bold;
}
footer a {
    text-decoration: none;
    color: black;
}