<s>
Sass	B-Language
(	O
short	O
for	O
syntactically	O
awesome	O
style	O
sheets	O
)	O
is	O
a	O
preprocessor	B-General_Concept
scripting	B-Language
language	I-Language
that	O
is	O
interpreted	B-Application
or	O
compiled	B-Language
into	O
Cascading	B-Language
Style	I-Language
Sheets	I-Language
(	O
CSS	B-Language
)	O
.	O
</s>
<s>
SassScript	O
is	O
the	O
scripting	B-Language
language	I-Language
itself	O
.	O
</s>
<s>
Sass	B-Language
consists	O
of	O
two	O
syntaxes	O
.	O
</s>
<s>
The	O
original	O
syntax	O
,	O
called	O
"	O
the	O
indented	O
syntax	O
,	O
"	O
uses	O
a	O
syntax	O
similar	O
to	O
Haml	B-Application
.	O
</s>
<s>
The	O
newer	O
syntax	O
,	O
SCSS	B-Language
(	O
Sassy	O
CSS	B-Language
)	O
,	O
uses	O
block	O
formatting	O
like	O
that	O
of	O
CSS	B-Language
.	O
</s>
<s>
The	O
indented	O
syntax	O
and	O
SCSS	B-Language
files	O
are	O
traditionally	O
given	O
the	O
extensions	O
.sass	B-Language
and	O
.scss	B-Language
,	O
respectively	O
.	O
</s>
<s>
Sass	B-Language
(	O
in	O
the	O
larger	O
context	O
of	O
both	O
syntaxes	O
)	O
extends	O
CSS	B-Language
by	O
providing	O
several	O
mechanisms	O
available	O
in	O
more	O
traditional	O
programming	O
languages	O
,	O
particularly	O
object-oriented	B-Language
languages	I-Language
,	O
but	O
that	O
are	O
not	O
available	O
to	O
CSS3	O
itself	O
.	O
</s>
<s>
When	O
SassScript	O
is	O
interpreted	B-Application
,	O
it	O
creates	O
blocks	O
of	O
CSS	B-Language
rules	O
for	O
various	O
selectors	O
as	O
defined	O
by	O
the	O
Sass	B-Language
file	O
.	O
</s>
<s>
The	O
Sass	B-Language
interpreter	B-Application
translates	O
SassScript	O
into	O
CSS	B-Language
.	O
</s>
<s>
Alternatively	O
,	O
Sass	B-Language
can	O
monitor	O
the	O
.sass	B-Language
or	O
.scss	B-Language
file	O
and	O
translate	O
it	O
to	O
an	O
output	O
.css	B-Language
file	O
whenever	O
the	O
.sass	B-Language
or	O
.scss	B-Language
file	O
is	O
saved	O
.	O
</s>
<s>
SCSS	B-Language
is	O
a	O
nested	O
metalanguage	O
and	O
a	O
superset	O
of	O
CSS	B-Language
,	O
as	O
valid	O
CSS	B-Language
is	O
valid	O
SCSS	B-Language
with	O
the	O
same	O
semantics	B-Application
.	O
</s>
<s>
SassScript	O
provides	O
the	O
following	O
mechanisms	O
:	O
variables	O
,	O
nesting	O
,	O
mixins	B-Language
,	O
and	O
selector	O
inheritance	B-Language
.	O
</s>
<s>
Sass	B-Language
was	O
initially	O
designed	O
by	O
Hampton	O
Catlin	O
and	O
developed	O
by	O
Natalie	O
Weizenbaum	O
.	O
</s>
<s>
After	O
its	O
initial	O
versions	O
,	O
Weizenbaum	O
and	O
Chris	O
Eppstein	O
have	O
continued	O
to	O
extend	O
Sass	B-Language
with	O
SassScript	O
,	O
a	O
scripting	B-Language
language	I-Language
used	O
in	O
Sass	B-Language
files	O
.	O
</s>
<s>
The	O
official	O
open-source	B-Application
Dart	B-Language
implementation	O
.	O
</s>
<s>
The	O
official	O
"	O
sass	B-Language
"	O
node	B-Language
module	O
on	O
npm	B-Language
,	O
which	O
is	O
Dart	B-Language
Sass	B-Language
compiled	B-Language
to	O
pure	O
JavaScript	O
.	O
</s>
<s>
The	O
official	O
"	O
sass-embedded	O
"	O
node	B-Language
module	O
which	O
is	O
a	O
JavaScript	O
wrapper	O
around	O
the	O
native	O
Dart	B-Language
executable	O
.	O
</s>
<s>
The	O
original	O
open-source	B-Application
Ruby	B-Language
implementation	O
created	O
in	O
2006	O
,	O
since	O
deprecated	O
due	O
to	O
the	O
lack	O
of	O
maintainers	O
and	O
reached	O
End-of-Life	O
in	O
March	O
2019	O
.	O
</s>
<s>
libSass	O
,	O
the	O
official	O
open-source	B-Application
C++	B-Language
implementation	O
,	O
deprecated	O
in	O
October	O
2020	O
.	O
</s>
<s>
The	O
deprecated	O
"	O
node-sass	O
"	O
node	B-Language
module	O
on	O
npm	B-Language
,	O
based	O
on	O
the	O
deprecated	O
libSass	O
.	O
</s>
<s>
JSass	O
,	O
an	O
unofficial	O
Java	B-Language
implementation	O
,	O
based	O
on	O
the	O
deprecated	O
libSass	O
.	O
</s>
<s>
phamlp	O
,	O
an	O
unofficial	O
Sass/SCSS	O
implementation	O
in	O
PHP	B-Application
.	O
</s>
<s>
Vaadin	B-Language
has	O
a	O
Java	B-Language
implementation	O
of	O
Sass	B-Language
.	O
</s>
<s>
Firebug	B-Operating_System
,	O
a	O
Firefox	B-Application
XUL	B-Application
(	O
"	O
legacy	O
"	O
)	O
extension	B-Operating_System
for	O
web	O
development	O
.	O
</s>
<s>
It	O
has	O
been	O
since	O
deprecated	O
in	O
favor	O
of	O
developer	O
tools	O
integrated	O
into	O
Firefox	B-Application
itself	O
.	O
</s>
<s>
It	O
stopped	O
working	O
since	O
Firefox	B-Application
57	O
dropped	O
support	O
for	O
XUL	B-Application
extensions	O
.	O
</s>
<s>
Sass	B-Language
allows	O
variables	O
to	O
be	O
defined	O
.	O
</s>
<s>
During	O
translation	O
,	O
the	O
values	O
of	O
the	O
variables	O
are	O
inserted	O
into	O
the	O
output	O
CSS	B-Language
document	O
.	O
</s>
<s>
SCSSSassCompiled	O
CSS	B-Language
$	O
primary-color	O
:	O
#3bbfce	O
;	O
</s>
<s>
CSS	B-Language
does	O
support	O
logical	O
nesting	O
,	O
but	O
the	O
code	O
blocks	O
themselves	O
are	O
not	O
nested	O
.	O
</s>
<s>
Sass	B-Language
allows	O
the	O
nested	O
code	O
to	O
be	O
inserted	O
within	O
each	O
other	O
.	O
</s>
<s>
More	O
complicated	O
types	O
of	O
nesting	O
including	O
namespace	O
nesting	O
and	O
parent	O
references	O
are	O
discussed	O
in	O
the	O
Sass	B-Language
documentation	O
.	O
</s>
<s>
Sass	B-Language
allows	O
for	O
iterating	O
over	O
variables	O
using	O
,	O
and	O
,	O
which	O
can	O
be	O
used	O
to	O
apply	O
different	O
styles	O
to	O
elements	O
with	O
similar	O
classes	O
or	O
ids	O
.	O
</s>
<s>
Mixins	B-Language
also	O
support	O
arguments	O
.	O
</s>
<s>
While	O
CSS3	O
supports	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
hierarchy	O
,	O
it	O
does	O
not	O
allow	O
selector	O
inheritance	B-Language
.	O
</s>
<s>
In	O
Sass	B-Language
,	O
inheritance	B-Language
is	O
achieved	O
by	O
inserting	O
a	O
line	O
inside	O
of	O
a	O
code	O
block	O
that	O
uses	O
the	O
@extend	O
keyword	O
and	O
references	O
another	O
selector	O
.	O
</s>
<s>
Sass	B-Language
supports	O
multiple	B-Application
inheritance	I-Application
.	O
</s>
<s>
At	O
the	O
2012	O
HTML5	O
Developer	O
Conference	O
,	O
Hampton	O
Catlin	O
,	O
the	O
creator	O
of	O
Sass	B-Language
,	O
announced	O
version	O
1.0	O
of	O
libSass	O
,	O
an	O
open	O
source	O
C++	B-Language
implementation	O
of	O
Sass	B-Language
developed	O
by	O
Catlin	O
,	O
Aaron	O
Leung	O
,	O
and	O
the	O
engineering	O
team	O
at	O
Moovweb	O
.	O
</s>
<s>
Current	O
Sass	B-Language
maintainer	O
,	O
Chris	O
Eppstein	O
,	O
has	O
expressed	O
intent	O
to	O
contribute	O
as	O
well	O
.	O
</s>
<s>
According	O
to	O
Catlin	O
,	O
libSass	O
can	O
be	O
"drop[ped]	O
into	O
anything	O
and	O
it	O
will	O
have	O
Sass	B-Language
in	O
it	O
...	O
You	O
could	O
drop	O
it	O
right	O
into	O
Firefox	B-Application
today	O
and	O
build	O
Firefox	B-Application
and	O
it	O
will	O
compile	O
in	O
there	O
.	O
</s>
<s>
Performance	O
–	O
Developers	O
have	O
reported	O
10x	O
speed	O
up	O
increases	O
over	O
the	O
Ruby	B-Language
implementation	O
of	O
Sass	B-Language
.	O
</s>
<s>
Easier	O
integration	O
–	O
libSass	O
makes	O
it	O
easier	O
to	O
integrate	O
Sass	B-Language
into	O
more	O
software	O
.	O
</s>
<s>
Before	O
libSass	O
,	O
tightly	O
integrating	O
Sass	B-Language
into	O
a	O
language	O
or	O
software	O
product	O
required	O
bundling	O
the	O
entire	O
Ruby	B-Language
interpreter	B-Application
.	O
</s>
<s>
By	O
contrast	O
,	O
libSass	O
is	O
a	O
statically	O
linkable	O
library	O
with	O
zero	O
external	O
dependencies	O
and	O
C-like	O
interface	O
,	O
making	O
it	O
easy	O
to	O
wrap	O
Sass	B-Language
directly	O
into	O
other	O
programming	O
languages	O
and	O
tools	O
.	O
</s>
<s>
For	O
example	O
,	O
open	O
source	O
libSass	O
bindings	O
now	O
exist	O
for	O
Node	B-Language
,	O
Go	B-Application
,	O
and	O
Ruby	B-Language
.	O
</s>
<s>
Compatibility	O
–	O
libSass	O
's	O
goal	O
is	O
full	O
compatibility	O
with	O
the	O
official	O
Ruby	B-Language
implementation	O
of	O
Sass	B-Language
.	O
</s>
