CodePen

HTML

            
              <!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1.0">

<style>

body { background: #e3e3e3; padding: 0; margin: 0; }
#backgroundTable {margin:0; padding:0; width:100% !important; line-height: 100% !important; background: #e3e3e3;}
#mainTable { background: #333333 }

@media (max-width: 640px) {
  #mainTable { width: 100% !important }
}

@media (max-width: 400px) {
  #contentTable td { display: block; width: 100% !important }
}


</style>



<title>HTML EMAIL INNIT!</title>
</head>

<body>

  <table cellpadding="20" cellspacing="0" border="0" id="backgroundTable">
	<tr>
		<td>

			<table cellpadding="0" cellspacing="0" border="0" align="center" id="mainTable" width="600" >
				<tr>
					<td>

						<table cellpadding="0" cellspacing="0" border="0" width="100%" align="left" id="contentTable" >
							<tr>
								<td height="100" width="100" bgColor="red">
                  &nbsp;
								</td>
                <td height="10" width="20">
                  &nbsp;
                </td>
                <td height="100" bgColor="blue">
                  &nbsp;
                </td>
							</tr>
						</table>
						
					</td>
				</tr>
			</table>



		</td>
	</tr> 
	</table>



</body>
</html>
            
          
!

↑ Insert the most common viewport meta tag

CSS

            
              
            
          
!
? ?
? ?
Must be a valid URL.
+ add another resource
via CSS Lint

JS

            
              
            
          
!
Must be a valid URL.
+ add another resource
via JS Hint
Loading ..................