Update layout
Update layout

- Use placeholders rather than mixins
- Rename page content block to #content so the skiplink from the govuk
template works
- Remove display:block from content, this is set by the govuk template
assuming <main id=“content”>

dudelmeister/ved,tjharrop/visa-fees,paulpod/drivingservices,adampotter/resource,adampotter/resource,tjharrop/electronic-visa-waiver,paulpod/dmsp,tjharrop/electronic-visa-waiver,rhianonymous/firstreg,paulpod/dvladesign,paulpod/driving,dudelmeister/full-prototype-kit,dwpdigitaltech/ejs-prototype,timpaul/vehicle_management_prototype,paulpod/vm,dudelmeister/ved,tjharrop/electronic-visa-waiver,paulpod/wedding,paulpod/evl,paulpod/fin,tjharrop/visa-fees,dwpdigitaltech/ejs-prototype,paulpod/driving,paulpod/firstreg,timpaul/govuk_patterns,paulpod/evl,paulpod/bulk,paulpod/vm.old,paulpod/fin,paulpod/dmsp,paulpod/vm.old,paulpod/firstreg,gup-dwp/pip-prototype,paulpod/fin,dwpdigitaltech/ejs-prototype,dudelmeister/full-prototype-kit,rhianonymous/firstreg,paulpod/drivingservices,gup-dwp/pip-prototype,timpaul/vehicle_management_prototype,paulpod/wedding,paulpod/bulk,paulpod/vm,paulpod/dvladesign,paulpod/fin,adampotter/resource,timpaul/govuk_patterns