CSSMutableStyleDeclaration::setProperty does not parse CSSPropertyColor property. e.g. in /editing/execCommand/modifyForeColorByCharacter.html, we add green color but parsed color has the RGBA32 value 0. Put a break point in executeApplyStyle (109 @ editing/EditorCommand.cpp). Inserting the following code would reveal this behavior: RefPtr<CSSValue> value = style->getPropertyCSSValue(propertyID); ASSERT(value->isPrimitiveValue()); CSSPrimitiveValue* pvalue = static_cast<CSSPrimitiveValue*>(value.get()); fprintf(stderr, "rgba32[%x] cssText[%s]\n", pvalue->getRGBA32Value(), pvalue->cssText().ascii().data()); which prints rgba32[0] cssText[green]