body {
    margin: 0;
    background-image: url(img/bruce-wayne-light.png);
    background-size: cover;
    background-position: center 10%;
    min-height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: center;
    transition: all 0.3s ease;
}



/* botão wayne */
button {
    padding: 15px 40px;
    font-size: 18px;
    letter-spacing: 2px;
    border: 2px solid #111;
    background: rgba(255, 255, 255, 0.8);
    color: #111;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: bold;
}

button:hover {
    background: #111;
    color: #fff;
    border-color: #fff;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.7);
}

/* frase wayne */
h1 {
    margin-top: 30px;
    text-align: center;
    color: #111;
    background: rgba(255, 255, 255, 0.6);
    padding: 15px 25px;
    font-style: italic;
}

/* modo batman */
body.batman {
    background-image: url(img/batman-dark.jpg);
    background-position: center 0%;
}

body.batman h1 {
    color: #fff;
    background: rgba(0, 0, 0, 0.6);
}

body.batman button {
    background: #111;
    color: #fff;
    border-color: #fff;
}

body.batman button:hover {
    background: rgba(255, 255, 255, 0.8);
    color: #111;
    border-color: #111;
    box-shadow: 0 0 15px rgba(255, 255, 255, 0.7);
}