The API docs are explicit here:
http://www.gnome.org/~billh/at-spi-idl/html/interfaceAccessibility_1_1Text.html#a18 

| /"Other text attributes should choose their names and value semantics 
| in accordance with relevant standards such as CSS level 2"/

The bridge is exporting the wrong names when people use the AtkTextAttribut enum (see http://developer.gnome.org/doc/API/2.0/atk/AtkText.html)

Most of them map well, with the unclear ones being underline/strikethrough, pixels-inside-wrap, full-height and wrap-mode.  Need more info on rise, scale and fg/bg-stipple.

Here are some specific notes:

ATK_TEXT_ATTR_LEFT_MARGIN   The pixel width of the left margin
left-margin (current) -> margin-left (CSS)

ATK_TEXT_ATTR_RIGHT_MARGIN  The pixel width of the right margin
right-margin (current) -> margin-right (CSS)

ATK_TEXT_ATTR_INDENT  The number of pixels that the text is indented
indent (current) -> text-indent (CSS)

ATK_TEXT_ATTR_INVISIBLE   Either "true" or "false" indicating whether text is visible or not
invisible (current) -> visibility: hidden (CSS)  (in CSS can be visible|hidden|collapsed)

ATK_TEXT_ATTR_EDITABLE  Either "true" or "false" indicating whether text is editable or not
Keep as is, no CSS property for this.

ATK_TEXT_ATTR_PIXELS_ABOVE_LINES  Pixels of blank space to leave above each newline-terminated line.
pixels-above-lines (current) -> padding-top (CSS)

ATK_TEXT_ATTR_PIXELS_BELOW_LINES  Pixels of blank space to leave below each newline-terminated line.
pixels-below-lines (current) -> padding-bottom (CSS)

ATK_TEXT_ATTR_PIXELS_INSIDE_WRAP  Pixels of blank space to leave between wrapped lines inside the same newline-terminated line (paragraph).
Unforunately this is modeled differently via CSS line-height

ATK_TEXT_ATTR_BG_FULL_HEIGHT  "true" or "false" whether to make the background color for each character the height of the highest font used on the current line, or the height of the font used for the current character.
No CSS ... XSLT?

ATK_TEXT_ATTR_RISE  Number of pixels that the characters are risen above the baseline
Don't know

ATK_TEXT_ATTR_UNDERLINE   "none", "single", "double" or "low"
ATK_TEXT_ATTR_STRIKETHROUGH   "true" or "false" whether the text is strikethrough
underline+strikethrough (current) -> text-decoration (CSS). 
Possible values are text-decoration are underline|overline|blink|none
There is no double or low in CSS. Can we use XSLT for that?

ATK_TEXT_ATTR_SIZE  The size of the characters.
size (current) -> font-size (CSS)

ATK_TEXT_ATTR_SCALE   The scale of the characters. The value is a string representation of a double
What does this mean?

ATK_TEXT_ATTR_WEIGHT  The weight of the characters.
weight (current) -> font-weight (CSS)

ATK_TEXT_ATTR_LANGUAGE  The language used
language (current) -> lang (W3C xml)

ATK_TEXT_ATTR_FAMILY_NAME   The font family name
family-name (current) -> font-family (CSS)

ATK_TEXT_ATTR_BG_COLOR  The background color. The value is an RGB value of the format "u,u,u"
bg-color (current) -> background-color (CSS)

ATK_TEXT_ATTR_FG_COLOR  The foreground color. The value is an RGB value of the format "u,u,u"
fg-color (current) -> color (CSS)

ATK_TEXT_ATTR_BG_STIPPLE  "true" if a GdkBitmap is set for stippling the background color.
ATK_TEXT_ATTR_FG_STIPPLE  "true" if a GdkBitmap is set for stippling the foreground color.
Need to look these up, there are some funky CSS background properties like background-repeat or something.

ATK_TEXT_ATTR_WRAP_MODE   The wrap mode of the text, if any. Values are "none", "char" or "word"
Don't know of CSS attribute for this. XSLT?

ATK_TEXT_ATTR_DIRECTION   The direction of the text, if set. Values are "none", "ltr" or "rtl"
Stays as is

ATK_TEXT_ATTR_JUSTIFICATION   The justification of the text, if set. Values are "left", "right", "center" or "fill"
justification (current) -> text-align (CSS)

ATK_TEXT_ATTR_STRETCH   The stretch of the text, if set. Values are "ultra_condensed", "extra_condensed", "condensed", "semi_condensed", "normal", "semi_expanded", "expanded", "extra_expanded" or "ultra_expanded"
stretch (current) maps well to font-stretch (CSS)

ATK_TEXT_ATTR_VARIANT   The capitalization variant of the text, if set. Values are "normal" or "small_caps"
variant (current) maps well to font-variant (CSS)

ATK_TEXT_ATTR_STYLE   The slant style of the text, if set. Values are "normal", "oblique" or "italic"
style (current) -> font-style (CSS)