body {
    display: block;
    margin: 8px;
    text-align: center;
    background-color: dimgrey;
}

.carousel-inner img {
    margin: auto;
}

.card img {
    margin: auto;
    background-color: teal;
}

.embed-container { 
    position: relative; 
    padding-bottom: 56.25%; 
    height: 0; 
    overflow: hidden; 
    max-width: 100%; 
}

.embed-container iframe, .embed-container object, .embed-container embed { 
    position: absolute; 
    top: 0; 
    left: 0;
     width: 100%;
      height: 100%;
}

.navigation {
    margin: 1em;
    padding: 1em;
}

.navigation a {
    background-color: teal;
    color: white;
    display: inline-block;
    padding: 10px;
    text-decoration: none;
    margin: 5px;
}

.navigation a:hover {
    color: black;
}