Design manager is a publishing feature available in publishing sites for both Sharepoint Server and Office 365. Using design manager you can brand the internet-facing websites in Sharepoint Server 2013 and Office 365.
Skills required:
- Having some knowledge of HTML and CSS
- Javascript
Open a Sharepoint publishing site,

Click site settings -> Design manager,

Before doing that I created some sample HTML and CSS,
Html
- <!DOCTYPE html>
- <html>
- <head>
- <meta charset="utf-8">
- <title>Masterpage coversion using Html and css</title>
- <link rel="stylesheet" type="text/css" href="css\custom.css"> </head>
- <body>
- <header>
- <p>this is my header </p>
- </header>
- <footer>
- <p>this is my footer</p>
- </footer>
- </body>
- </html>
- header{
- background-color: blue;
- }
- footer{
- background-color : green;
- }
- p{
- font-family: callibri;
- font-weight: bold;
- font-size:22px;
- }
Click on Upload design files.

Map the master page gallery to network drive for copying the HTML Structure.
URL: http://trenmaxorgs/sites/pubs/_catalogs/masterpage/

Copy and paste the HTML and css files here,

Now open Design Manager.
Click Edit master page.
Select Convert an HTML file into a Sharepoint masterpage,
Select the HTML file created and click insert.
So now the conversion has been successful without errors,

So now the master has been generated successfully

Here is the final result,


Vinodh NarayananPosted Jul 31, 2017, 5:02 AM
Just place the data div in between your header and footer it works perfect
Raghu ReddyPosted Jul 31, 2017, 1:43 AM
I have tried with the given css and html ,Header and Footer both are displaying on top only. Please let me know how t orectify this