.embed-responsive {
position: relative;
display: block;
width: 100%;
padding: 0;
overflow: hidden;
}
.embed-responsive::before {
display: block;
content: "";
}
.embed-responsive .embed-responsive-item,
.embed-responsive iframe,
.embed-responsive embed,
.embed-responsive object,
.embed-responsive video {
position: absolute;
top: 0;
bottom: 0;
left: 0;
width: 100%;
height: 100%;
border: 0;
}
/* Seitenverhältnis 21:9 ============*/
.embed-responsive-21by9::before {
padding-top: 42.857143%;
}
/* Seitenverhältnis 16:9 ============*/
.embed-responsive-16by9::before {
padding-top: 56.25%;
}
/* Seitenverhältnis 4:3 =============*/
.embed-responsive-4by3::before {
padding-top: 75%;
}
/* Seitenverhältnis 1:1 =============*/
.embed-responsive-1by1::before {
padding-top: 100%;
}
Beispiel
<!-- eingebetteter iFrame mit Seitenverhältnis 16:9 -->
<div class="embed-responsive embed-responsive-16by9">
<iframe class="embed-responsive-item" src="https://www.google.com/maps/embed?pb=!1m0!4v1506798052044!6m8!…"></iframe>
</div>