html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

body {
    background: url("../img/gnumber.jpg") no-repeat center center fixed;
    background-size: cover;
    font-family: Arial, sans-serif;
    color: #fff;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

header {
    background-color: rgba(0, 0, 0, 0.85);
    padding: 20px;
    border-radius: 8px;
    width: 60%;
    margin-bottom: 20px;
    text-align: center;
    font-size: 1.3em;
}

#main {
    background-color: rgba(0, 0, 0, 0.85);
    max-width: 100%;
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.6);
    font-size: 1.3em;
}

input[type="text"] {
    padding: 8px;
    border-radius: 4px;
    border: none;
    text-align: center;
    margin-top: 10px;
    margin-bottom: 10px;
}

button {
    padding: 10px 20px;
    border-radius: 4px;
    border: none;
    cursor: pointer;
    background-color: #1b991f;
    color: white;
    font-weight: bold;;
    transition: background-color 0.3s ease;
}

button:hover {
    background-color: #45a049;
}

#resetBtn {
    background-color: #2196F3;
}

#resetBtn:hover {
    background-color: #1E88E5;
}

#feedback {
    font-size: 1.2em;
    margin-top: 15px;
    height: 1.5em;
}

div {
    margin-top: 10px;
}