This is a minimal markup your web page should have in order to be validated with the W3C Markup Validation Service
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>title</title> <link rel="stylesheet" href="style.css"> <script src="script.js"></script> </head> <body> <!-- page content --> </body> </html>
Every HTML document should start with a declaration that tells the browser what version of HTML the document is written in. This code has been specifically designed to “fool” current browsers (that are yet to support HTML5) into treating the document as a full-blooded HTML4 document. Browser versions as far back as Internet Explorer 6 will render the page with their most standards-compliant rendering mode.
The tag should specify the primary language for the document’s content with the a attribute.
The first bit in the header should be a tag that specifies the character encoding of the page. Usually, the character encoding is declared by the web server that sends the page to the browser, but many servers are not configured to send this information. Specifying it here ensures the document is displayed correctly even when it’s loaded directly from disk, without consulting a server.
Several related tips:
Always add a trailing slash to sub folder references. Otherwise, you generate two requests to the server: first, it will add the slash and second, create a new real request.
To refresh a page every 30 seconds use this in the page head:
<meta http-equiv="refresh" content="30">
Specify width and height for img element. In this case the space for the image will be reserved by a browser, and the layout won’t change:
<img src="#" width="200" height="200" alt="image" />