Emmet abbreviations and snippets for a page skeleton with WAI-ARIA landmark roles and a default meta viewport declaration. For Sublime Text Mac users, save this file in ~/emmet. For other editors/OSes find your default location for emmet overrides.

snippets.json

{
  "html": {
    "snippets": {
      "page": "<header role=\"banner\">\n\t<nav role=\"navigation\">\n\t\t${1}\n\t</nav>\n</header>\n<div role=\"main\">\n\t${2}\n</div>\n<footer role=\"contentinfo\">\n\t${3}\n</footer>",
      "meta:vpm": "<meta name=\"viewport\" content=\"initial-scale=1.0, width=device-width\" />"
    },
    "abbreviations": {
    	"doc": "html>(head>meta[charset=UTF-8]+meta:vpm+title{${1:Document}})+body",
    	"!:page": "html:5>page"
    }
  }
}