Why Does The Validation Fail ?
Validating your website is useful to give you an indication of the validity of the CSS and HTML that is output on your site. This CSS and HTML is ouput by your CMS, template, extensions, scripts and content you add to your site. We make extensive use of CSS3, HTML5 markup and best practices to deliver modern web technology to your projects. Great care is taken to adopt only widely accepted best techniques.
The W3C Validation service, for example, may show you that your newly installed template is not 100% valid as per its specifications because it does not recognise widely adopted modern markup as yet or has an issue detecting them. Let us take a look at some examples of what is commonly flagged as "Invalid" markup;
The X-UA-Compatible meta tag
This is a meta tag that is used to force IE to use the highest mode available in a visitors browser and if a visitor has the Google Chrome frame plugin installed, they get the benefits of Google Chrome wrapped into their IE Browser. The HTML Validator will currently fail this.
The Background Property and Vendor Prefixes
The CSS Validator, will also fail validation for the use of the background CSS3 property and vendor prefixes that are commonly used., like the examples below.background: -moz-linear-gradient(-45deg, #40a4b6 0%, #007181 100%); background: -webkit-linear-gradient(-45deg, #40a4b6 0%,#007181 100%); background: linear-gradient(-45deg, #40a4b6 0%,#007181 100%);
Validation is an important part of your toolkit ( for detecting 'real' errors) but don't let it hold you back from adopting well established modern and progressive techniques.