Install FFmpeg with homebrew. You'll need to install it with a couple flags for webm and the AAC audio codec.
brew install ffmpeg --with-libvpx --with-libvorbis --with-fdk-aac --with-opus
img { | |
opacity: 0; | |
-webkit-transition: opacity .2s; | |
-moz-transition: opacity .2s; | |
-o-transition: opacity .2s; | |
transition: opacity .2s; | |
} | |
img:loaded { | |
opacity: 1; |