/**
 * iframe
 */
.nb-iframe {
    margin-bottom: 1rem;
    margin-top: 1rem;
    padding-top: 100%;
    position: relative;
}

.nb-iframe iframe {
    border: none;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
}

@media only screen and (min-width: 600px) {

    .nb-iframe {
        padding-top: 56.25%;
    }

    .nb-iframe--square {
        padding-top: 100%;
    }

    .nb-iframe--tv {
        padding-top: 75%;
    }

    .nb-iframe--35mm {
        padding-top: 66.67%;
    }
}