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

body {
    display: flex;
    justify-content: center;
    align-items: center;

    background: linear-gradient(
        135deg,
        #18252d 0%,
        #233943 30%,
        #3e6d74 70%,
        #6dbdc0 100%
    );

    background-attachment: fixed;
    background-size: cover;
}

.logo {
    width: 175px;          /* ajuste conforme necessário */
    max-width: 80vw;
    height: auto;

    filter: drop-shadow(0 8px 20px rgba(0,0,0,.35));

    /* animação suave */
    animation: fadeIn 1.2s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}