<s>
Stylish	B-Operating_System
is	O
a	O
user	O
style	O
manager	O
that	O
can	O
change	O
the	O
appearance	O
of	O
web	O
pages	O
in	O
a	O
user	O
's	O
browser	O
without	O
changing	O
their	O
content	O
by	O
including	O
user-supplied	O
CSS	B-Language
style	I-Language
sheets	I-Language
with	O
those	O
supplied	O
by	O
the	O
web	O
site	O
itself	O
.	O
</s>
<s>
The	O
Stylish	B-Operating_System
browser	B-Protocol
extension	I-Protocol
includes	O
tools	O
with	O
which	O
to	O
write	O
user	O
styles	O
,	O
and	O
can	O
install	O
user	O
styles	O
written	O
by	O
other	O
Stylish	B-Operating_System
users	O
from	O
a	O
companion	O
website	O
.	O
</s>
<s>
Stylish	B-Operating_System
was	O
originally	O
developed	O
by	O
Jason	O
Barnabe	O
as	O
an	O
XUL/XPCOM	O
add-on	O
for	O
Mozilla	B-Application
Firefox	I-Application
.	O
</s>
<s>
A	O
Chrome	B-Application
extension	O
followed	O
in	O
2010	O
,	O
which	O
was	O
released	O
for	O
Blink-based	O
Opera	B-Application
15	O
in	O
2013	O
and	O
as	O
a	O
Firefox	B-Application
WebExtension	O
in	O
2017	O
.	O
</s>
<s>
Similar	O
extensions	O
for	O
Safari	B-Application
and	O
for	O
Presto-based	O
Opera	B-Application
are	O
distributed	O
as	O
'	O
Stylish	B-Operating_System
 '	O
by	O
other	O
developers	O
with	O
Barnabe	O
's	O
approval	O
.	O
</s>
<s>
User	O
styles	O
are	O
CSS	B-Language
code	O
designed	O
to	O
alter	O
the	O
appearance	O
of	O
one	O
,	O
some	O
,	O
or	O
all	O
sites	O
.	O
</s>
<s>
Stylish	B-Operating_System
for	O
Firefox	B-Application
can	O
additionally	O
style	O
the	O
skin	O
of	O
the	O
browser	O
itself	O
,	O
but	O
the	O
Android	B-Application
version	O
does	O
not	O
support	O
this	O
because	O
the	O
user	O
interface	O
is	O
built	O
in	O
native	O
Android	B-Application
code	O
.	O
</s>
<s>
User	O
styles	O
are	O
added	O
to	O
the	O
CSS	B-Language
rules	O
provided	O
by	O
the	O
site	O
,	O
but	O
can	O
also	O
override	O
the	O
site	O
's	O
styling	O
(	O
often	O
requiring	O
the	O
!	O
important	O
keyword	O
for	O
each	O
replacement	O
rule	O
)	O
.	O
</s>
<s>
App	O
styles	O
change	O
the	O
appearance	O
of	O
the	O
Firefox	B-Application
user	O
interface	O
,	O
only	O
supported	O
on	O
Firefox	B-Application
.	O
</s>
<s>
It	O
is	O
similar	O
to	O
the	O
userChrome.css	O
CSS	B-Language
file	O
used	O
by	O
Firefox	B-Application
and	O
Mozilla-based	O
browsers	O
.	O
</s>
<s>
In	O
September	O
2016	O
Jason	O
Barnabe	O
,	O
the	O
creator	O
of	O
Stylish	B-Operating_System
and	O
userstyles.org,	O
announced	O
that	O
,	O
having	O
lost	O
interest	O
in	O
the	O
project	O
,	O
he	O
had	O
"	O
chosen	O
Justin	O
Hindman	O
as	O
the	O
next	O
leader	O
of	O
Stylish	B-Operating_System
and	O
userstyles.org	B-Operating_System
.	O
"	O
</s>
<s>
Hindman	O
had	O
no	O
prior	O
connection	O
to	O
either	O
Stylish	B-Operating_System
or	O
userstyles.org,	O
and	O
it	O
soon	O
became	O
clear	O
that	O
Barnabe	O
had	O
simply	O
sold	O
them	O
to	O
Hindman	O
in	O
a	O
straw	O
purchase	O
for	O
Israeli	O
analytics	O
company	O
SimilarWeb	B-Application
.	O
</s>
<s>
In	O
December	O
2016	O
Hindman	O
began	O
releasing	O
updates	O
to	O
Stylish	B-Operating_System
for	O
Chrome	B-Application
which	O
returned	O
a	O
perfect	O
replica	O
of	O
the	O
user	O
's	O
browsing	O
activity	O
to	O
Userstyles	O
.	O
</s>
<s>
On	O
3	O
January	O
2017	O
he	O
announced	O
a	O
"	O
partnership	O
"	O
with	O
SimilarWeb	B-Application
in	O
which	O
"	O
Stylish	B-Operating_System
users	O
 [ would ] 	O
be	O
joining	O
SimilarWeb	B-Application
’s	O
market	O
research	O
panel.	O
"	O
.	O
</s>
<s>
A	O
Firefox	B-Application
web	O
extension	O
(	O
3.0.1	O
)	O
was	O
released	O
on	O
10	O
November	O
,	O
after	O
a	O
final	O
update	O
(	O
2.1.1	O
)	O
to	O
the	O
Stylish	B-Operating_System
XUL+XPCOM	O
add-on	O
on	O
31	O
October	O
to	O
migrate	O
user	O
styles	O
to	O
a	O
webextension-compatible	O
database	O
.	O
</s>
<s>
In	O
July	O
2018	O
,	O
after	O
these	O
issues	O
were	O
publicized	O
by	O
a	O
software	O
engineer	O
,	O
Stylish	B-Operating_System
was	O
pulled	O
from	O
both	O
the	O
Chrome	B-Application
Web	I-Application
Store	I-Application
and	O
Mozilla	B-Operating_System
Add-ons	O
,	O
as	O
well	O
as	O
being	O
automatically	O
uninstalled	O
for	O
all	O
existing	O
users	O
.	O
</s>
<s>
Stylish	B-Operating_System
returned	O
to	O
Mozilla	B-Operating_System
Add-ons	O
on	O
16	O
August	O
and	O
to	O
the	O
Chrome	B-Application
Web	I-Application
Store	I-Application
on	O
5	O
November	O
with	O
the	O
same	O
logic	O
but	O
sporting	O
a	O
new	O
opt-in	O
page	O
asking	O
users	O
to	O
agree	O
to	O
the	O
data	O
collection	O
when	O
the	O
extension	O
was	O
installed	O
.	O
</s>
<s>
Firefox	B-Application
now	O
reports	O
fewer	O
users	O
of	O
Stylish	B-Operating_System
than	O
its	O
more	O
popular	O
alternative	O
,	O
Stylus	B-Operating_System
.	O
</s>
<s>
A	O
userscript	B-Language
manager	I-Language
such	O
as	O
Greasemonkey	B-Operating_System
or	O
Tampermonkey	B-Operating_System
can	O
add	O
a	O
local	O
style	O
sheet	O
to	O
a	O
web	O
page	O
by	O
adding	O
the	O
style	O
sheet	O
content	O
to	O
an	O
HTML	O
tag	O
and	O
adding	O
the	O
tag	O
to	O
the	O
page	O
.	O
</s>
<s>
User	O
styles	O
from	O
Userstyles.org	B-Operating_System
can	O
be	O
downloaded	O
as	O
user	O
scripts	O
for	O
use	O
with	O
a	O
userscript	B-Language
manager	I-Language
.	O
</s>
<s>
Alternative	O
user	O
style	O
managers	O
include	O
Stylus	B-Operating_System
and	O
xStyle	O
,	O
which	O
are	O
derived	O
from	O
Stylish	B-Operating_System
for	O
Chrome	B-Application
,	O
aStyle	O
,	O
reStyle	O
,	O
and	O
Website	O
Theme	O
Manager	O
.	O
</s>
<s>
In	O
Firefox	B-Application
,	O
user	O
styles	O
for	O
web	O
sites	O
and	O
browser	O
chrome	B-Application
can	O
be	O
added	O
to	O
local	O
files	O
userContent.css	O
or	O
userChrome.css	O
,	O
respectively	O
.	O
</s>
<s>
As	O
of	O
Firefox	B-Application
69	O
,	O
user	O
must	O
switch	O
the	O
toolkit.legacyUserProfileCustomizations.stylesheets	O
preference	O
to	O
true	O
in	O
about:config	O
in	O
order	O
to	O
load	O
these	O
files	O
.	O
</s>
