Website in IE is shown by default in compatibility mode.

Use the following tag:

<meta http-equiv="X-UA-Compatible" content="IE=edge" /> 

If possible, instead of edge, specify a specific version of IE. For example, 8 or 10.
Use edge with caution, because:

Web developers are advised to use this mode only on test pages. Unpredictable results are possible when rendering the page content in future versions of Windows Internet Explorer.

In addition, if the user has compatibility mode enabled by default, then this tag will not work. You will need to use special headers.

using php

 <?php header('X-UA-Compatible: IE=edge'); ?> 

or using .htaccess (used in HTML5 Boilerplate )

 <IfModule mod_headers.c> Header set X-UA-Compatible "IE=Edge,chrome=1" # mod_headers can't match by content-type, but we don't want to send this header on *everything*... <FilesMatch "\.(appcache|crx|css|eot|gif|htc|ico|jpe?g|js|m4a|m4v|manifest|mp4|oex|oga|ogg|ogv|otf|pdf|png|safariextz|svg|svgz|ttf|vcf|webm|webp|woff|xml|xpi)$"> Header unset X-UA-Compatible </FilesMatch> </IfModule> 

Question: Why can IE go to "compatibility mode" on my site?
Answer: There are several reasons for this.

• Previously, when viewing the site, the button "viewing in compatibility mode" was pressed;
  
• the switching occurred automatically due to some content that caused the IE renderer error and forced it to roll back to the old version of the renderer;
  
• compatibility mode was enabled by default for all sites;
  
• IE counted the site as part of your intranet and switched to compatibility mode;
  
• The site is listed by Microsoft as a site that requires the inclusion of compatibility mode;

Here is a detailed diagram of the interaction between IE and the document mode: