- Off Canvas Menu with CSS :target | CSS-Tricks
"Off Canvas" patterns are different ways to approach layout where content on the web isn’t just laid out in a vertical column. For instance, navigation could be positioned hidden off the left edge of the "canvas" (visible browser window) and slid in on demand.
- Responsive background images with fixed or fluid aspect ratios – Voormedia
The trick we will use to maintain the aspect ratio is to apply vertical padding. We set the padding as a percentage based on the width of the element. This technique is originally described for embedded videos in an older A List Apart article but it works just as well for any element.