Responsive iframe (for Google Maps and such). Thanks to Niklaus Gerber: http://niklausgerber.com/blog/responsive-google-or-bing-maps/

sample.html

<!-- Responsive iFrame -->
<div class="flexible-container">
    <iframe>i</iframe>
</div

style.css

/* Flexible iFrame */
.flexible-container {
    position: relative;
    padding-bottom: 56.25%; /* adjust to reach desired ratio */
    padding-top: 30px;
    height: 0;
    overflow: hidden;
}
.flexible-container iframe,   
.flexible-container object,  
.flexible-container embed {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}