body {margin: auto; max-width: 100ex;}
h1, h2 {font-family: sans-serif; clear: both}
pre {margin-left: 5ex; padding: 0.5em 0 0.5em 1em; color: blue}
pre strong {color: red}
code {color: blue}
a {text-decoration: none}

img {float: right; width: 50%; margin-left: 1ex; border: thin black solid; padding: 1ex}
iframe  {height: 65ex; width: 108ex; margin-left: 2ex; border: none}
iframe.shorter {height: 10ex;}
iframe.short   {height: 45ex;}
iframe.long    {height: 80ex;}
iframe.longer  {height: 95ex;}
.source {text-align: right}