body {
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
}
.contenedor {
    display: flex;
    justify-content: center;
    flex-direction: column;
    margin: 2em;
}
.menu {
    display: flex;
    justify-content: center;
    width: 100%;
    background-color: royalblue;

}
.menu a {
    font-size: 1.5em;
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    text-align: center;
    /* background-color: lightgreen; */
    /* border: 1px dotted red; */
    margin: 10px;
}
.menu a:hover {
    color: rgba(255, 255, 255, 1)
}

.aviso {
    display: flex;
    justify-content: center; 
    width: 100%;
    background-color: yellow;
}

tr {
    border: 5px dotted black;
}