look at deng. granted it does not handle gif's, but if you cannot write a server side function to change an image type, well learn...
here is the deng feature list:
DENG Feature List
Home
CSS
* CSS 2 box model
* Full cascade and inheritence
* Support for initial, default, user and author styles
* Support for XML Namespaces
* CSS 2/3 selectors
o Universal selector
o Type selectors
o Attribute selectors
+ E[foo]
+ E[foo="bar"]
+ E[foo~="bar"]
+ E[foo^="bar"]
+ E[foo$="bar"]
+ E[foo*="bar"]
+ E[foo|="bar"]
o Class selectors
o ID selectors
o Combinators
+ Descendant combinator (E F)
+ Child combinators (E > F)
+ Adjacent sibling combinators (E + F)
+ Indirect adjacent combinator (E ~ F)
o Pseudo classes
+ :link
+ :root
+ :first-child
+ :last-child
+ :first-of-type
+ :last-of-type
+ :only-child
+ :only-of-type
+ :empty
+ :contains()
+ :not()
o Pseudo elements
+ ::before
+ ::after
+ ::value
o Selectors and namespaces
+ ns|E
+ *|E
+ |E
+ E
* At-rules
o @import
o @namespace
* Associating stylesheets thru:
o XML stylesheet processing instruction <?xml-stylesheet href=".."?>
o <link> element (XHTML)
o <style> element (XHTML, SVG)
o Style attribute <div style="..">
o Presentational attributes <g fill="..">
o @import rules
* CSS Linking extension for defining CSS properties to make any XML element's content or attribute values be a link (e.g. making the <link> element in RSS behave as if it has a <a href="...">, including "target").
* Generated CSS content, :before and :after pseudo-classes
XHTML
* Supported tags (stylable with CSS):
o <a>
o <address>
o <b>
o <blockquote>
o <body>
o <div>
o <em>
o <h1>-<h6>
o <head>
o <hr>
o <html>
o <i>
o <img>
o <link>
o <p>
o <pre>
o <span>
o <strong>
o <style>
o <title>
XForms, CSS UI
* Core Model Binding: loading XML instances and binding nodes to user interface controls - <input>, <output>, <select> and <select1>, with multiple models per XForms.
* Full support for XPath
* XML submission
* Repeats (for datagrid / table look-up aggregate controls)
* Model binding for <label>, deriving label values from the XForms instance
* Full CSS styling of text entry / output area of <input>, <output> controls with the CSS 3 Basic UI module's ::value pseudo-element
* Supported tags (stylable with CSS):
o <action>
o <bind>
o <delete>
o <group>
o <input>
o <insert>
o <instance>
o <item>
o <label>
o <message>
o <model>
o <output>
o <repeat>
o <secret>
o <select1>
o <send>
o <setindex>
o <setvalue>
o <submission>
o <submit>
o <textarea>
o <trigger>
o <value>
XFrames
* Basic XFrames implementation
* Supports target attribute on <a> element for XHTML documents inside an XFrame in DENG loading other DENG content into another XFrame.
SVG
* Support for paths (excl. arcs) and basic shapes
* Styling through CSS and presentational attributes
* Basic transformations (translate, scale, rotate, skew)
* Asyncronous rendering, each path rendered one at the time in SVG document order, resulting in an animated loading effect of the SVG image.
* SVG tidying of exported SVGs from Illustrator 9 / 10 and SVG Factory (for export from e.g. Freehand) for optimized rendering of SVGs in DENG (DENG web service edition only).
* Supported tags (stylable with CSS):
o <a>
o <circle>
o <def>
o <ellipse>
o <g>
o <line>
o <path>
o <polygon>
o <polyline>
o <rect>
o <style>
o <svg>
so maybe you are wrong and should admit it now ;)