body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f5f5f7;
    color: #333;
}

.container {
    background-color: white;
    border-radius: 10px;
    padding: 30px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: relative;
}

h1 {
    text-align: center;
    margin-bottom: 30px;
    color: #1d1d1f;
    font-size: 40px;
    user-select: none;
}

h2 {
    border-bottom: 1px solid black;
    margin-top: 25px;
    margin-bottom: 35px;
}

.home-button {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 30px;
    height: 30px;
    cursor: pointer;
    font-size: 18px;
    color: #999;
    transition: color 0.2s ease;
    z-index: 10;
}

.home-button:hover {
    color: #333;
}

a.button {
    padding: 10px 20px;
    border: none;
    background-color: coral;
    color: white;
    border-radius: 5px;
    text-decoration: none;
    box-shadow: 2px 2px 1px gray;
    text-align: center;
}

.button-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    max-width: 600px;
    margin: 0 auto;
}

img {
    display: block;
    border: 5px solid #555;
    max-width: 100%;
    height: auto;
    transition: transform 0.3s ease;
    transform-origin: center center;
}

img.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
    border-radius: 2px;
    box-shadow: 2px 2px 1px rgba(0, 0, 0, 0.1);
}

.footer {
    margin-top: 30px;
    text-align: center;
    font-size: 14px;
    color: #666;
    cursor: default;
}

.footer:hover {
    text-decoration: underline;
}

#topBtn {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background-color: #007bff;
    color: white;
    padding: 12px 18px;
    font-size: 16px;
    border: none;
    border-radius: 6px;
    text-decoration: none;
    cursor: pointer;
    display: none;
    z-index: 10000;
}