Going ahead with the switch to tabs. This is a major coding standards change! If any unusual parser bugs show up, check this changeset. Converted all .php, .js, .tpl, .css, and .json files and did basic testing.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>{PAGE_NAME} • {SITE_NAME}</title>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
{JS_DYNAMIC_VARS}
<link rel="stylesheet" type="text/css" href="{CDNPATH}/includes/clientside/css/enano-shared.css" />
<link rel="stylesheet" type="text/css" href="{CDNPATH}/themes/{THEME_ID}/css-extra/structure.css" />
<link id="mdgCss" rel="stylesheet" type="text/css" href="{CDNPATH}/themes/{THEME_ID}/css/{STYLE_ID}.css" />
{JS_HEADER}
{ADDITIONAL_HEADERS}
</head>
<body class="simple">
<div id="header">
<h1>{PAGE_NAME}</h1>
</div>
<!-- Yes this is table based. For reliability reasons. -->
<table border="0" cellspacing="0" cellpadding="0" id="body-wrapper">
<tr>
<td valign="top" id="cell-content">
<div id="content-wrapper" class="content">
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td valign="top">
<div id="ajaxEditContainer">