Today I Learned

A collection of useful bits & bobs I'd rather not forget
Scaling a CSS container within bounds

In CSS constraining an element within the bounds of it's parent whilst maintaining it's aspect ratio is harder than you might imagine. This little JS Fiddle from danield770 was just the ticket:

div#constrained-element {
  width:       100vw;
  height:      56.25vw; /* 100/56.25 = 1.778 */
  max-height:  100vh;
  max-width:   177.78vh; /* 16/9 = 1.778 */
  margin:      auto;
  position:    absolute;
  top:         0;
  bottom:      0; 
  left:        0;
  right:       0;

Effectively it uses the CSS3 viewport width/height property to calculate the proper size (in this case 16:9).

Things I learned on other days →