[CSS3] Use Sticky positioning for section Headers

We can take advantage of sticky positioning to keep a section header at the top of the page while the user scrolls. This was useful for neat categorisation of sections on the page.

  <DL>    <DT>Premier League</DT>    <DD>Brighton & Hove Albion 2-2 AFC Bournemouth</DD>    <DD>Burnley 1-2 Liverpool</DD>    <DD>Leicester City 3-0 Huddersfield Town</DD>    <DD>Stoke City 0-1 Newcastle</DD>    <DD>Everton 0-1 Manchester</DD>    <DT>Championship</DT>    <DD>Bolton Wanderers 1-0 Hull City</DD>    <DD>Derby County 1-1 Sheffield</DD>    <DD>Leeds 0-0 Nottingham Forest</DD>    <DD>Norwich City 2-1 Millwall</DD>    <DD>Preston North End 2-3 Middlesbrough</DD>    <DD>Queens Park Rangers 2-1 Cardiff City</DD>    <DD>Sheffield Wednesday 0-3 Burton Albion</DD>    <DD>Sunderland 0-1 Barnsley</DD>    <DD>Aston Villa 3-0 Bristol City</DD>    <DT>League 1</DT>    <DD>AFC Wimbledon 2-0 Southend</DD>    <DD>Bristol Rovers 2-1 Portsmouth</DD>    <DD>Charlton Athletic 1-2 Gillingham</DD>    <DD>Fleetwood Town 1-2 Bradford City</DD>    <DD>Northampton Town 0-1 Wigan Athletic</DD>    <DD>Oxford 3-1 Milton Keynes Dons</DD>    <DD>Peterborough 1-1 Doncaster Rovers</DD>    <DD>Plymouth Argyle 1-0 Walsall</DD>    <DD>Rochdale 1-2 Blackpool</DD>    <DD>Rotherham 1-1 Blackburn Rovers</DD>    <DD>Scunthorpe 1-0 Bury</DD>    <DD>Shrewsbury Town 1-0 Oldham Athletic</DD>  </DL>

{  font-size: 30px;}  {  background-color: mediumseagreen;    position: sticky;  /* Sticky positioning */   position: -webkit-sticky;   top: 0;}  {  padding: 20px 0;}

[CSS3] Use Sticky positioning to section Headers