W3C mobileOK Checker

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Detailed report

1. Images/Objects

   Images and/or image objects must be delivered in an appropriate format and dimensions so that they can be retrieved and rendered by most mobile browsers. mobileOK requires that all images and rendered objects be either GIF or JPEG images.

   • [low] The embedded image or object is not of type image/gif or image/jpeg (image/png)
     The document contains images that are not in GIF or JPEG format, or are not correctly served by the Web server. Images in formats other than GIF or JPEG may not work on some mobile browsers.

     • Convert with an image editor the said images either to GIF or to JPEG, depending on the type of images;
     • Either update the links to these new versions, or use Content Negotiation to have both versions available and served depending on the browser capabilities.

     Triggered by http://mtld.mobi/files/dotMobi_logo_small.png.

     Related best practice:
     [CONTENT_FORMAT_SUPPORT] Send content in a format that is known to be supported by the device.

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1. Style sheets

   The most efficient way to control the layout of a page is to use CSS style sheets. To use them well in a mobile browser, it is important to ensure that the CSS style sheets referenced by a page and the CSS styles directly defined in the page are valid, and e.g. make a good use of the @media rules.

   • The resource does not specify UTF-8 as character encoding
     One of the resources required to render the page (most likely a CSS style sheet) does not declare its encoding as UTF-8 in an HTTP Content-Type header. Check that its content is properly encoded, and consider declaring its encoding at the HTTP level.

     Triggered by http://mtld.mobi/themes/dotmobi_mobile/devmobi/devmobi.css:

     check the Content-Type HTTP header

     Related best practice:
     [CHARACTER_ENCODING_USE] Indicate in the response the character encoding being used.
   • The CSS style sheet contains rules referencing the position, display or float properties
     Support for CSS style sheets varies from one device to the other, and cannot be entirely relied upon, especially to position the elements precisely. Floating and absolutely positioned elements should also be avoided on limited screens for usability reason since they may trigger scrolling in two directions.

     Triggered 4 times by http://mtld.mobi/themes/dotmobi_mobile/devmobi/devmobi.css:

     … display:inline

     … float:left

     … position:inside

     … display: inline

     Related best practice:
     [STYLE_SHEETS_SUPPORT] Organize documents so that if necessary they may be read without style sheets.
   • The CSS Style contains at-rules, properties, or values that may not be supported
     Support for CSS varies from one device to the other. It is relatively safe to assume that mobile devices that support CSS support the CSS Level 1 grammar along with the @media attribute.

     Triggered by http://mtld.mobi/themes/dotmobi_mobile/devmobi/devmobi.css:

     Line 62 — Unknown pseudo-element or pseudo-class :hover

     Related best practice:
     [STYLE_SHEETS_USE] Use style sheets to control layout and presentation, unless the device is known not to support them.
2. At the HTTP level

   The source of the messages in this category is to be found in the HTTP headers that were sent along with the page. They are most likely due to the Web server configuration for static files, or the way the server-side scripts are written for dynamic content. Making sure that HTTP headers are correctly defined is essential in a mobile context with a usually low bandwidth and high latency.

   • The "Expires" header contains a date in the past
     An Expires date set in the past prevents browsers from caching the content, and thus requires them to retrieve it through the network every time.

     If the resource needs to be revalidated each time it is queried by users, consider using the Last-Modified and/or ETag HTTP headers to limit the complete retrieval of the resource to the cases where the resource has changed. See Mark Nottingham's tutorial on caching to learn more about these techniques.

     Triggered by the resource under test.

     Related best practice:
     [CACHING] Provide caching information in HTTP responses.
   • A cache related header or a meta http-equiv value contains an invalid value
     An unknown value in a caching directive may be the result of a typo, and could prevent browsers from properly handling the caching information.

     Triggered 2 times by the resource under test:

     Invalid value post-check

     Invalid value pre-check

     Related best practice:
     [CACHING] Provide caching information in HTTP responses.
   • The document is not served as "application/xhtml+xml"
     The recommended media type for serving XHTML is application/xhtml+xml. More browsers are likely to support that media type, and optimize the rendering for it. application/vnd.wap.xhtml+xml is widely used and supported in mobile networks as well but is unlikely to be supported by non-mobile browsers.

     See how to properly configure server mime types. If the page under test uses a non-XML version of HTML, you should first consider switching to XHTML. In any case, do not serve a non-XML version of HTML with an application/xhtml+xml media type.
     Beware: some browsers have no support for application/xhtml+xml (e.g. Internet Explorer) and prompt users to download pages served as such. You should not serve XHTML content to browsers that do not support it. Use Content Negotiation to match the browser's capabilities. See the XHTML Media Types - Second Edition W3C note for more information and in particular the Compatibility Guidelines to follow to have XHTML documents rendered on both XHTML-aware and HTML-only user agents.

     Triggered by the resource under test:

     served as text/html

     Related best practice:
     [CONTENT_FORMAT_SUPPORT] Send content in a format that is known to be supported by the device.
3. Links

   Following a link may require cost, time, and attention from users in a mobile context. When a user follows a link that leads to nowhere, or cannot be rendered by the browser, the user experience is poor.

   • The linked resource character encoding may not be appropriate for mobile devices
     The linked resource uses a character encoding other than UTF-8. Given the number of character encodings used across the world, sending UTF-8 encoded content to browsers that requests it increases significantly the chances of properly displaying a page.

     Learn more about declaration of character encoding.

     Triggered by http://ready.mobi/:

     character encoding ""

     Related best practice:
     [LINK_TARGET_FORMAT] Note the target file's format unless you know the device supports it.

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