This page will display tag support and CSS support amongst e-readers. This was all tested using an ePub or MOBI file, all well-formed. Note that MOBI does not directly support any CSS. Instead the KindleGen or other conversion tool must translate the source CSS into something MOBI format can understand.

For MUCH easier reading/editing of this document, it now lives as a google doc - Device Compatibly on Docs.google google doc that everyone can edit. The table listed below is a snapshot in HTML format and may not reflect the latest changes but it easier for MobileRead users to search.

Contents 1 Legend 2 HTML Compatibility 3 CSS Compatibility 4 NCX Compatibility 5 Footnotes 6 For more information

[edit] Legend

NT	Not Tested
-	Not Supported
+	Supported

[edit] HTML Compatibility

Device → Tag ↓	iBooks	Nook Color	Kindle 2	Kindle App on iPad	Kindle App on Android Tablet	Nook App on iPad	Nook App on Android	Kobo	Kobo App on the iPad	Sony PRS505
H1-H6	+	+	NT	NT	NT	NT	+	+	+	NT
div	+	+	NT	NT	NT	NT	+	+	+	NT
p	+	+	NT	NT	NT	NT	+	+	+	NT
blockquote	+	+	NT	NT	NT	+	+	+	+	NT
img	+	+	NT	NT	NT	NT	+	+	+	NT
hr	+	+	NT	NT	NT	NT	+	+	+	NT
pre	+	+	NT	NT	NT	NT	+	+	+	NT
ol->li	+	+[1]	NT	NT	NT	NT	+	+	+	NT
ul->li	+	+	NT	NT	NT	NT	+	+	+	NT
dl->dt->dd	+	+	NT	NT	NT	NT	+	+	+	NT
em	+	+	NT	NT	NT	NT	+	+	+	NT
strong	+	+	NT	NT	NT	NT	+	+	+	NT
small	+	+	NT	NT	NT	NT	+	+	+	NT
q	+	-	NT	NT	NT	NT	-	-	+	NT
i	+	+	NT	NT	NT	NT	+	+	+	NT
b	+	+	NT	NT	NT	NT	+	+	+	NT
u[2]	+	+	NT	NT	NT	NT	-	NT	NT	NT
sub	+	+	NT	NT	NT	NT	+	+	+	NT
sup	+	+	NT	NT	NT	NT	+	+	+	NT
code	+	+	NT	NT	NT	NT	+	+	+	NT
samp	+	+	NT	NT	NT	NT	+	+	+	NT
var	+	+	NT	NT	NT	NT	+	+	+	NT
kbd	+	+	NT	NT	NT	NT	+	+	+	NT
span	+	+	NT	NT	NT	NT	+	+	+	NT
ins	+	+	NT	NT	NT	NT	+	+	+	NT
del	+	+	NT	NT	NT	NT	+	+	+	NT
abbr	+	+	NT	NT	NT	NT	NT	-	-	NT
dfn	+	+	NT	NT	NT	NT	+	+	-	NT
cite	+	+	NT	NT	NT	NT	+	+	+	NT
table->thead ->tr->td->tfooter	+	+	NT	NT	NT	NT	NT	-	+	NT

[edit] CSS Compatibility

Device → Property ↓	iBooks	Nook Color	Kindle 2	Kindle Fire	Kindle App on iPad	Kindle App on Android Tablet	Nook App on iPad	Nook App on Android	Kobo	Kobo App on the iPad	Sony PRS505
:first-child	+	-	NT	NT	NT	NT	NT	NT	NT	NT	NT
:first-line	+	-	NT	NT	NT	NT	NT	NT	-	+	NT
:first-letter	+	-	NT	NT	NT	NT	NT	NT	-	+	NT
:before	+	-	NT	NT	NT	NT	NT	NT	-	NT	NT
:after	+	-	NT	NT	NT	NT	NT	NT	-	NT	NT
position:relative	+	-	NT	NT	NT	NT	NT	NT	-	+	NT
position:absolute	+	-	NT	NT	NT	NT	NT	NT	-	+	NT
float	+	+	-	+	NT	-	NT	+	+	+	NT
display	+	+	NT	+	NT	NT	NT	NT	+	+	NT
overflow	+	+	NT	NT	NT	NT	NT	+	-	+	NT
background-color	+	+	+[3]	NT	NT	NT	NT	+	+	+	NT
Height/width	+	+	NT	NT	NT	NT	NT	+	+	+	NT
Margin	NT	NT	+	+	NT	NT	NT	NT	+	+[4]	NT
Padding	NT	NT	-	NT	NT	NT	NT	NT	+	+	NT
page-break-before (auto, always, avoid)	+	+	NT	NT	NT	NT	NT	+	+	-	NT
page-break-before (left, right)	-	NT	NT	NT	NT	NT	NT	+	NT	NT	NT
page-break-after (auto, always, avoid)	+	+	NT	NT	NT	NT	+	NT	+	-	NT
page-break-after (left, right)	-	NT	NT	NT	NT	NT	NT	NT	NT	NT	NT
page-break-inside	NT	NT	NT	NT	NT	NT	NT	NT	NT	NT	NT
font-size	NT	NT	NT	NT	NT	NT	NT	NT	+	+[5]	NT
font-style	+	+	NT	NT	NT	NT	NT	+	+	+	NT
font-weight	+	+	NT	NT	NT	NT	NT	+	+	+	NT
text-indent	+	+	NT	NT	NT	NT	NT	+	+	+	NT
text-align	+	+	NT	NT	NT	NT	NT	+	+	+	NT
text-decoration	+	+	NT	NT	NT	NT	NT	+	+	+	NT
letter-spacing	+	-	NT	NT	NT	NT	NT	-	-	+	NT
word-spacing	+	-	NT	NT	NT	NT	NT	-	-	+	NT
text-transform	+	-	+	+	NT	NT	NT	-	-	+	NT
text-shadow	+	-	NT	NT	NT	NT	NT	NT	NT	NT	NT

[edit] NCX Compatibility

Device → Feature ↓	iBooks	Nook Color	Kindle 2	Kindle App on iPad	Kindle App on Android Tablet	Nook App on iPad	Nook App on Android	Kobo	Kobo App on the iPad	Sony PRS505
Nesting navPoints	+	-	-	NT	NT	NT	NT	-	+	+
Spine files omitted from navMap	NT	NT	NT	NT	NT	NT	NT	+[6]	-	NT

[edit] Footnotes

1. ↑ Nook Color ... ordered lists ???
2. ↑ The underline <u> tag was deprecated in XHTML 1.0 Transitional, and removed from XHTML 1.0 Strict and XHTML 1.1, and thus isn't valid in an EPUB.
3. ↑ Kindle 2 only displays background color in table cells
4. ↑ Kobo App on the iPad does not support margin-top or margin-bottom.
5. ↑ Kobo App on the iPad only supports font-size on inline tags, e.g. span.
6. ↑ Kobo displays files omitted from navMap, but bought books will be preprocessed to add all such files to the TOC, using the file's first handful of words as its title.

[edit] For more information

• EPub Reader Test - a similar page
• Testing file