#anuncio-evento {
    position: fixed;
    top: 20px;
    left: 20px;
    z-index: 99999;
    max-width: 350px;
}

#anuncio-evento img {
    display: block;
    width: 100%;
    height: auto;
}

#anuncio-evento .cerrar {
    position: absolute;
    top: -10px;
    right: -10px;

    width: 28px;
    height: 28px;

    background: #000;
    color: #fff;
    border-radius: 50%;

    font-family: Arial, sans-serif;
    font-size: 18px;
    line-height: 28px;
    text-align: center;

    cursor: pointer;
    z-index: 2;
}

@media (max-width: 600px) {
    #anuncio-evento {
        width: 80%;
        max-width: 300px;
        right: 10%;
        bottom: 15px;
    }
}