diff --git a/src/doc/ca/intro/conf.py b/src/doc/ca/intro/conf.py
index 2f4eb7f1873..e46ebfb8c8d 100644
--- a/src/doc/ca/intro/conf.py
+++ b/src/doc/ca/intro/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/ca/intro', '{filename}'),
+})
+
 # General information about the project.
 project = "Introducció de Sage"
 
diff --git a/src/doc/common/static/custom-furo.css b/src/doc/common/static/custom-furo.css
index fc76a3f7c0f..ae75c2b6383 100644
--- a/src/doc/common/static/custom-furo.css
+++ b/src/doc/common/static/custom-furo.css
@@ -21,3 +21,17 @@ a.pdf:hover {
   text-decoration: none;
 }
 
+/* Style for announcement banner */
+
+.announcement {
+    background: orange;
+}
+
+.announcement-content {
+    color: black;
+}
+
+.announcement-content a {
+    color: white;
+    text-decoration: none;
+}
diff --git a/src/doc/de/a_tour_of_sage/conf.py b/src/doc/de/a_tour_of_sage/conf.py
index 47355ae5a22..33f9e9642b7 100644
--- a/src/doc/de/a_tour_of_sage/conf.py
+++ b/src/doc/de/a_tour_of_sage/conf.py
@@ -22,6 +22,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/de/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = "Ein Rundgang durch Sage"
 name = "a_tour_of_sage"
diff --git a/src/doc/de/thematische_anleitungen/conf.py b/src/doc/de/thematische_anleitungen/conf.py
index 7f2753ab0e4..d3a843c30bd 100644
--- a/src/doc/de/thematische_anleitungen/conf.py
+++ b/src/doc/de/thematische_anleitungen/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/de/thematische_anleitungen', '{filename}'),
+})
+
 # General information about the project.
 project = "Thematische Anleitungen"
 name = 'ThematischeAnleitungen-de'
diff --git a/src/doc/de/tutorial/conf.py b/src/doc/de/tutorial/conf.py
index 8d18c44aa6b..fe4c5b0d3e1 100644
--- a/src/doc/de/tutorial/conf.py
+++ b/src/doc/de/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/de/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Sage Tutorial"
 name = 'SageTutorial-de'
diff --git a/src/doc/en/a_tour_of_sage/conf.py b/src/doc/en/a_tour_of_sage/conf.py
index 14ecb994215..38184747c9f 100644
--- a/src/doc/en/a_tour_of_sage/conf.py
+++ b/src/doc/en/a_tour_of_sage/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, f'blob/develop/src/doc/en/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = "A Tour of Sage"
 
diff --git a/src/doc/en/constructions/conf.py b/src/doc/en/constructions/conf.py
index 37215f418c6..13743e5b276 100644
--- a/src/doc/en/constructions/conf.py
+++ b/src/doc/en/constructions/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/constructions', '{filename}'),
+})
+
 # General information about the project.
 project = "Constructions"
 
diff --git a/src/doc/en/developer/conf.py b/src/doc/en/developer/conf.py
index 9dcfc261ed1..58e0ca995b7 100644
--- a/src/doc/en/developer/conf.py
+++ b/src/doc/en/developer/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/developer', '{filename}'),
+})
+
 # General information about the project.
 project = "Developer Guide"
 
diff --git a/src/doc/en/faq/conf.py b/src/doc/en/faq/conf.py
index 42c3378b129..fab823b6592 100644
--- a/src/doc/en/faq/conf.py
+++ b/src/doc/en/faq/conf.py
@@ -22,6 +22,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/faq', '{filename}'),
+})
+
 # General information about the project.
 project = "FAQ"
 
diff --git a/src/doc/en/installation/conf.py b/src/doc/en/installation/conf.py
index e50bf3c1c57..41f91e228d0 100644
--- a/src/doc/en/installation/conf.py
+++ b/src/doc/en/installation/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/installation', '{filename}'),
+})
+
 # General information about the project.
 project = "Installation Guide"
 
diff --git a/src/doc/en/prep/conf.py b/src/doc/en/prep/conf.py
index bbc6663b3df..3dc26674397 100644
--- a/src/doc/en/prep/conf.py
+++ b/src/doc/en/prep/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/prep', '{filename}'),
+})
+
 # General information about the project.
 project = "PREP Tutorials"
 copyright = "2012, Rob Beezer, Karl-Dieter Crisman, and Jason Grout"
diff --git a/src/doc/en/reference/conf.py b/src/doc/en/reference/conf.py
index 86aa0b05a81..d9bb5da5acb 100644
--- a/src/doc/en/reference/conf.py
+++ b/src/doc/en/reference/conf.py
@@ -25,6 +25,11 @@
 ref_src = os.path.join(SAGE_DOC_SRC, 'en', 'reference')
 ref_out = os.path.join(SAGE_DOC, 'html', 'en', 'reference')
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/reference/index.rst'),
+})
+
 # General information about the project.
 project = "Reference Manual"
 
diff --git a/src/doc/en/reference/conf_sub.py b/src/doc/en/reference/conf_sub.py
index b6f20311d68..8346b13c9f4 100644
--- a/src/doc/en/reference/conf_sub.py
+++ b/src/doc/en/reference/conf_sub.py
@@ -42,6 +42,11 @@
     title = name.capitalize()
 title = title.replace('`', '$')
 
+# We use the directory's name to add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, f'blob/develop/src/doc/en/reference/{name}', '{filename}'),
+})
+
 # General information about the project.
 project = title
 
diff --git a/src/doc/en/thematic_tutorials/conf.py b/src/doc/en/thematic_tutorials/conf.py
index 3b638d40173..19f9a3da5af 100644
--- a/src/doc/en/thematic_tutorials/conf.py
+++ b/src/doc/en/thematic_tutorials/conf.py
@@ -22,6 +22,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/thematic_tutorials', '{filename}'),
+})
+
 # General information about the project.
 project = "Thematic Tutorials"
 
diff --git a/src/doc/en/tutorial/conf.py b/src/doc/en/tutorial/conf.py
index 8a4f626f440..7b475a3bb6e 100644
--- a/src/doc/en/tutorial/conf.py
+++ b/src/doc/en/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/en/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Tutorial"
 
diff --git a/src/doc/es/a_tour_of_sage/conf.py b/src/doc/es/a_tour_of_sage/conf.py
index 1bf598c11f5..b6f43afd2da 100644
--- a/src/doc/es/a_tour_of_sage/conf.py
+++ b/src/doc/es/a_tour_of_sage/conf.py
@@ -22,6 +22,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/es/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = 'Un Tour Por Sage'
 name = 'a_tour_of_sage'
diff --git a/src/doc/es/tutorial/conf.py b/src/doc/es/tutorial/conf.py
index bbebf61f532..913dfc06025 100644
--- a/src/doc/es/tutorial/conf.py
+++ b/src/doc/es/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/es/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Sage Tutorial"
 name = 'tutorial-es'
diff --git a/src/doc/fr/a_tour_of_sage/conf.py b/src/doc/fr/a_tour_of_sage/conf.py
index f6438ea695a..19c047882bf 100644
--- a/src/doc/fr/a_tour_of_sage/conf.py
+++ b/src/doc/fr/a_tour_of_sage/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/fr/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = 'Sage en quelques mots'
 name = 'a_tour_of_sage'
diff --git a/src/doc/fr/tutorial/conf.py b/src/doc/fr/tutorial/conf.py
index f44315072ff..87c13353111 100644
--- a/src/doc/fr/tutorial/conf.py
+++ b/src/doc/fr/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/fr/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Tutoriel Sage"
 name = 'tutorial-fr'
diff --git a/src/doc/hu/a_tour_of_sage/conf.py b/src/doc/hu/a_tour_of_sage/conf.py
index 90517269f2e..590be9195cb 100644
--- a/src/doc/hu/a_tour_of_sage/conf.py
+++ b/src/doc/hu/a_tour_of_sage/conf.py
@@ -22,6 +22,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/hu/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = 'A Sage bemutatása'
 name = 'a_tour_of_sage'
diff --git a/src/doc/it/a_tour_of_sage/conf.py b/src/doc/it/a_tour_of_sage/conf.py
index f897b790c2a..6d217dee7ec 100644
--- a/src/doc/it/a_tour_of_sage/conf.py
+++ b/src/doc/it/a_tour_of_sage/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/it/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = 'Esplora Sage'
 name = 'a_tour_of_sage'
diff --git a/src/doc/it/faq/conf.py b/src/doc/it/faq/conf.py
index b5a536d383b..c2cd668d0f8 100644
--- a/src/doc/it/faq/conf.py
+++ b/src/doc/it/faq/conf.py
@@ -22,6 +22,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/it/faq', '{filename}'),
+})
+
 # General information about the project.
 project = "Sage FAQ"
 
diff --git a/src/doc/it/tutorial/conf.py b/src/doc/it/tutorial/conf.py
index 1f3bdec9367..13bfa100034 100644
--- a/src/doc/it/tutorial/conf.py
+++ b/src/doc/it/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/it/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Tutorial Sage"
 name = 'tutorial-it'
diff --git a/src/doc/ja/a_tour_of_sage/conf.py b/src/doc/ja/a_tour_of_sage/conf.py
index 451d7cc5b58..105cae0a93d 100644
--- a/src/doc/ja/a_tour_of_sage/conf.py
+++ b/src/doc/ja/a_tour_of_sage/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/ja/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = "Sage ガイドツアー"
 name = 'a_tour_of_sage'
diff --git a/src/doc/ja/tutorial/conf.py b/src/doc/ja/tutorial/conf.py
index e4b79bd7875..ef32faab6b8 100644
--- a/src/doc/ja/tutorial/conf.py
+++ b/src/doc/ja/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/ja/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Sage チュートリアル"
 name = 'tutorial-jp'
diff --git a/src/doc/pt/a_tour_of_sage/conf.py b/src/doc/pt/a_tour_of_sage/conf.py
index 10d9367f942..075e2d7a4f5 100644
--- a/src/doc/pt/a_tour_of_sage/conf.py
+++ b/src/doc/pt/a_tour_of_sage/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/pt/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = 'Uma Turnê pelo Sage'
 name = 'a_tour_of_sage'
diff --git a/src/doc/pt/tutorial/conf.py b/src/doc/pt/tutorial/conf.py
index f299582db9a..13582d8b896 100644
--- a/src/doc/pt/tutorial/conf.py
+++ b/src/doc/pt/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/pt/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Tutorial Sage"
 name = 'tutorial-pt'
diff --git a/src/doc/ru/tutorial/conf.py b/src/doc/ru/tutorial/conf.py
index cda4d9762ed..5ff38a94d50 100644
--- a/src/doc/ru/tutorial/conf.py
+++ b/src/doc/ru/tutorial/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, 'blob/develop/src/doc/ru/tutorial', '{filename}'),
+})
+
 # General information about the project.
 project = "Sage Tutorial in Russian"
 name = 'tutorial-ru'
diff --git a/src/doc/tr/a_tour_of_sage/conf.py b/src/doc/tr/a_tour_of_sage/conf.py
index f969a1b516a..c1854ee2f42 100644
--- a/src/doc/tr/a_tour_of_sage/conf.py
+++ b/src/doc/tr/a_tour_of_sage/conf.py
@@ -20,6 +20,11 @@
 # contains common paths.
 html_static_path = [] + html_common_static_path
 
+# Add a small edit button.
+html_theme_options.update({
+  'source_edit_link': os.path.join(source_repository, f'blob/develop/src/doc/tr/a_tour_of_sage', '{filename}'),
+})
+
 # General information about the project.
 project = 'Sage Turu'
 name = 'a_tour_of_sage'
diff --git a/src/sage/misc/sageinspect.py b/src/sage/misc/sageinspect.py
index 039212c53eb..3957598771d 100644
--- a/src/sage/misc/sageinspect.py
+++ b/src/sage/misc/sageinspect.py
@@ -3,14 +3,6 @@
 
 This module extends parts of Python's inspect module to Cython objects.
 
-AUTHORS:
-
-- originally taken from Fernando Perez's IPython
-- William Stein (extensive modifications)
-- Nick Alexander (extensions)
-- Nick Alexander (testing)
-- Simon King (some extension for Cython, generalisation of SageArgSpecVisitor)
-
 EXAMPLES::
 
     sage: from sage.misc.sageinspect import *
@@ -21,10 +13,8 @@
 
     sage: sage_getfile(sage.rings.rational)
     '.../rational.pyx'
-
     sage: sage_getdoc(sage.rings.rational).lstrip()
     'Rational Numbers...'
-
     sage: sage_getsource(sage.rings.rational)
     '# distutils: ...Rational Numbers...'
 
@@ -32,10 +22,8 @@
 
     sage: sage_getfile(sage.misc.sageinspect)
     '.../sageinspect.py'
-
     sage: print(sage_getdoc(sage.misc.sageinspect).lstrip()[:40])
     Inspect Python, Sage, and Cython objects
-
     sage: sage_getsource(sage.misc.sageinspect).lstrip()[5:-1]
     'Inspect Python, Sage, and Cython objects...'
 
@@ -45,10 +33,8 @@
 
     sage: sage_getfile(sage.rings.rational.Rational)
     '.../rational.pyx'
-
     sage: sage_getdoc(sage.rings.rational.Rational).lstrip()
     'A rational number...'
-
     sage: sage_getsource(sage.rings.rational.Rational)
     'cdef class Rational...'
 
@@ -56,10 +42,8 @@
 
     sage: sage_getfile(BlockFinder)
     '.../sage/misc/sageinspect.py'
-
     sage: sage_getdoc(BlockFinder).lstrip()[:50]
-    'Provide a tokeneater() method to detect the...'
-
+    'Provide a "tokeneater()" method to detect the end '
     sage: sage_getsource(BlockFinder)
     'class BlockFinder:...'
 
@@ -69,13 +53,10 @@
 
     sage: sage_getdef(sage.rings.rational.make_rational, obj_name='mr')
     'mr(s)'
-
     sage: sage_getfile(sage.rings.rational.make_rational)
     '.../rational.pyx'
-
     sage: sage_getdoc(sage.rings.rational.make_rational).lstrip()
     'Make a rational number ...'
-
     sage: sage_getsource(sage.rings.rational.make_rational)
     '@cython.binding(True)\ndef make_rational(s):...'
 
@@ -83,13 +64,10 @@
 
     sage: sage_getdef(sage.misc.sageinspect.sage_getfile, obj_name='sage_getfile')
     'sage_getfile(obj)'
-
     sage: sage_getfile(sage.misc.sageinspect.sage_getfile)
     '.../sageinspect.py'
-
     sage: sage_getdoc(sage.misc.sageinspect.sage_getfile).lstrip()
     'Get the full file name associated to "obj" as a string...'
-
     sage: sage_getsource(sage.misc.sageinspect.sage_getfile)[4:]
     'sage_getfile(obj):...'
 
@@ -98,7 +76,6 @@
 
     sage: sage_getdef(''.find, 'find')
     'find(*args, **kwds)'
-
     sage: sage_getdef(str.find, 'find')
     'find(*args, **kwds)'
 
@@ -112,6 +89,22 @@ def foo(unsigned int x=1, a=')"', b={not (2+1==3):'bar'}, *args, **kwds): return
     sage: sage_getargspec(foo)
     FullArgSpec(args=['x', 'a', 'b'], varargs='args', varkw='kwds', defaults=(1, ')"', {False: 'bar'}), kwonlyargs=[], kwonlydefaults=None, annotations={})
 
+AUTHORS:
+
+- Originally taken from Fernando Perez's IPython
+- William Stein: extensive modifications
+- William Stein: in :func:`_sage_getargspec_cython`, a modified version of
+  ``inspect.getargspec`` from the Python Standard Library, which was taken from
+  IPython for use in Sage
+- Nick Alexander: extensions, testing
+- Simon King: some extension for Cython, generalisation of SageArgSpecVisitor
+- Simon King: in :func:`sage_getsourcelines`, if a class has no docstring then let the
+  class definition be found starting from the ``__init__`` method.
+- Simon King: in :func:`sage_getsourcelines`, get source lines for dynamic classes
+- Simon King: in :func:`_sage_getargspec_cython`, return an ``ArgSpec``, fix some bugs
+- Simon King (2011-09): added :func:`_sage_getsourcelines_name_with_dot`
+- Simon King (2013-02): in :func:`_sage_getargspec_cython`, recognise varargs and
+  default values in cython code, and return an ``ArgSpec``
 """
 
 import ast
@@ -200,7 +193,9 @@ def isclassinstance(obj):
     r"""
     Check if argument is instance of non built-in class
 
-    INPUT: ``obj`` -- object
+    INPUT:
+
+    - ``obj`` -- object
 
     EXAMPLES::
 
@@ -282,11 +277,6 @@ def _extract_embedded_position(docstring):
         ....:     print(f.read())
         cpdef test_funct(x,y): return
 
-    AUTHORS:
-
-    - William Stein
-    - Extensions by Nick Alexander
-    - Extension for interactive Cython code by Simon King
     """
     try:
         res = __embedded_position_re.search(docstring)
@@ -334,10 +324,6 @@ def _extract_embedded_signature(docstring, name):
 
     INPUT: ``docstring`` (string)
 
-    AUTHORS:
-
-    - Simon King
-
     EXAMPLES::
 
         sage: from sage.misc.sageinspect import _extract_embedded_signature
@@ -349,6 +335,7 @@ def _extract_embedded_signature(docstring, name):
         FullArgSpec(args=['self', 'x', 'r'], varargs='args', varkw='kwds', defaults=((1, 2, 3.4),), kwonlyargs=[], kwonlydefaults=None, annotations={})
         sage: _extract_embedded_signature(range.__call__.__doc__, '__call__')
         ('Call self as a function.', None)
+
     """
     # If there is an embedded signature, it is in the first line
     L = docstring.split(os.linesep, 1)
@@ -370,7 +357,7 @@ def _extract_embedded_signature(docstring, name):
 
 class BlockFinder:
     """
-    Provide a tokeneater() method to detect the end of a code block.
+    Provide a :meth:`tokeneater` method to detect the end of a code block.
 
     This is the Python library's :class:`inspect.BlockFinder` modified
     to recognize Cython definitions.
@@ -444,8 +431,8 @@ def _extract_source(lines, lineno):
 
     INPUT:
 
-    - ``lines`` - string or list of strings
-    - ``lineno`` - positive integer
+    - ``lines`` -- string or list of strings
+    - ``lineno`` -- positive integer
 
     EXAMPLES::
 
@@ -494,6 +481,7 @@ class SageArgSpecVisitor(ast.NodeVisitor):
         'jc'
         sage: visitor.visit(v.value)
         ['veni', 'vidi', 'vici']
+
     """
     def visit_Name(self, node):
         """
@@ -501,11 +489,9 @@ def visit_Name(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
+        - ``node`` -- the node instance to visit
 
-        - None, True, False, or the ``node``'s name as a string.
+        OUTPUT: ``None``, ``True``, ``False``, or the ``node``'s name as a string
 
         EXAMPLES::
 
@@ -516,6 +502,7 @@ def visit_Name(self, node):
             ['foo', 'bar']
             sage: [type(vis(n)) for n in ['foo', 'bar']]
             [<class 'str'>, <class 'str'>]
+
         """
         return node.id
 
@@ -530,9 +517,7 @@ def visit_NameConstant(self, node):
 
         - ``node`` - the node instance to visit
 
-        OUTPUT:
-
-        - None, True, False.
+        OUTPUT: ``None``, ``True``, ``False``
 
         EXAMPLES::
 
@@ -543,6 +528,7 @@ def visit_NameConstant(self, node):
             [True, False, None]
             sage: [type(vis(n)) for n in ['True', 'False', 'None']]
             [<class 'bool'>, <class 'bool'>, <class 'NoneType'>]
+
         """
         return node.value
 
@@ -560,9 +546,7 @@ def visit_arg(self, node):
 
         - ``node`` -- the node instance to visit
 
-        OUTPUT:
-
-        the argument name
+        OUTPUT: the argument name
 
         EXAMPLES::
 
@@ -572,6 +556,7 @@ def visit_arg(self, node):
             sage: args = ast.parse(s).body[0].args.args
             sage: [visitor.visit_arg(n) for n in args]
             ['a', 'b', 'c', 'd']
+
         """
         return node.arg
 
@@ -581,11 +566,9 @@ def visit_Num(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
+        - ``node`` -- the node instance to visit
 
-        - the number the ``node`` represents
+        OUTPUT: the number the ``node`` represents
 
         EXAMPLES::
 
@@ -608,11 +591,9 @@ def visit_Str(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
+        - ``node`` -- the node instance to visit
 
-        - the string the ``node`` represents
+        OUTPUT: the string the ``node`` represents
 
         EXAMPLES::
 
@@ -621,6 +602,7 @@ def visit_Str(self, node):
             sage: vis = lambda x: visitor.visit_Str(ast.parse(x).body[0].value)
             sage: [vis(s) for s in ['"abstract"', "'syntax'", r'''r"tr\ee"''']]
             ['abstract', 'syntax', 'tr\\ee']
+
         """
         return node.value
 
@@ -630,11 +612,9 @@ def visit_List(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
+        - ``node`` -- the node instance to visit
 
-        - the list the ``node`` represents
+        OUTPUT: the list the ``node`` represents
 
         EXAMPLES::
 
@@ -643,6 +623,7 @@ def visit_List(self, node):
             sage: vis = lambda x: visitor.visit_List(ast.parse(x).body[0].value)
             sage: [vis(l) for l in ['[]', "['s', 't', 'u']", '[[e], [], [pi]]']]
             [[], ['s', 't', 'u'], [['e'], [], ['pi']]]
+
         """
         t = []
         for n in node.elts:
@@ -655,11 +636,9 @@ def visit_Tuple(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
+        - ``node`` -- the node instance to visit
 
-        - the tuple the ``node`` represents
+        OUTPUT: the tuple the ``node`` represents
 
         EXAMPLES::
 
@@ -668,6 +647,7 @@ def visit_Tuple(self, node):
             sage: vis = lambda x: visitor.visit_Tuple(ast.parse(x).body[0].value)
             sage: [vis(t) for t in ['()', '(x,y)', '("Au", "Al", "Cu")']]
             [(), ('x', 'y'), ('Au', 'Al', 'Cu')]
+
         """
         t = []
         for n in node.elts:
@@ -680,11 +660,9 @@ def visit_Dict(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
+        - ``node`` -- the node instance to visit
 
-        - the dictionary the ``node`` represents
+        OUTPUT: the dictionary the ``node`` represents
 
         EXAMPLES::
 
@@ -694,6 +672,7 @@ def visit_Dict(self, node):
             sage: v = [vis(d) for d in ['{}', "{1:one, 'two':2, other:bother}"]]
             sage: [sorted(d.items(), key=lambda x: str(x[0])) for d in v]
             [[], [(1, 'one'), ('other', 'bother'), ('two', 2)]]
+
         """
         d = {}
         for k, v in zip(node.keys, node.values):
@@ -706,15 +685,9 @@ def visit_BoolOp(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
-
-        - The result that ``node`` represents
-
-        AUTHOR:
+        - ``node`` -- the node instance to visit
 
-        - Simon King
+        OUTPUT: the result that ``node`` represents
 
         EXAMPLES::
 
@@ -745,15 +718,9 @@ def visit_Compare(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
-
-        - The result that ``node`` represents
-
-        AUTHOR:
+        - ``node`` -- the node instance to visit
 
-        - Simon King
+        OUTPUT: the result that ``node`` represents
 
         EXAMPLES::
 
@@ -797,15 +764,9 @@ def visit_BinOp(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
-
-        - The result that ``node`` represents
-
-        AUTHOR:
+        - ``node`` -- the node instance to visit
 
-        - Simon King
+        OUTPUT: the result that ``node`` represents
 
         EXAMPLES::
 
@@ -814,6 +775,7 @@ def visit_BinOp(self, node):
             sage: vis = lambda x: visitor.visit(ast.parse(x).body[0].value)
             sage: [vis(d) for d in ['(3+(2*4))', '7|8', '5^3', '7/3', '7//3', '3<<4']] #indirect doctest
             [11, 15, 6, 2.3333333333333335, 2, 48]
+
         """
         op = node.op.__class__.__name__
         if op == 'Add':
@@ -867,15 +829,9 @@ def visit_UnaryOp(self, node):
 
         INPUT:
 
-        - ``node`` - the node instance to visit
-
-        OUTPUT:
-
-        - The result that ``node`` represents
-
-        AUTHOR:
+        - ``node`` -- the node instance to visit
 
-        - Simon King
+        OUTPUT: the result that ``node`` represents
 
         EXAMPLES::
 
@@ -901,7 +857,7 @@ def _grep_first_pair_of_parentheses(s):
 
     INPUT:
 
-    A string
+    - ``s`` -- a string
 
     OUTPUT:
 
@@ -924,6 +880,7 @@ def _grep_first_pair_of_parentheses(s):
         Traceback (most recent call last):
         ...
         SyntaxError: The given string does not contain balanced parentheses
+
     """
     out = []
     single_quote = False
@@ -956,7 +913,7 @@ def _split_syntactical_unit(s):
 
     INPUT:
 
-    - ``s``, a string
+    - ``s`` -- a string
 
     OUTPUT:
 
@@ -1101,12 +1058,10 @@ def _sage_getargspec_from_ast(source):
 
     INPUT:
 
-    - ``source`` - a string; the function's (or method's) source code
+    - ``source`` -- a string; the function's (or method's) source code
       definition.  The function's body is ignored.
 
-    OUTPUT:
-
-    - an instance of :obj:`inspect.ArgSpec`, i.e., a named tuple
+    OUTPUT: an instance of :obj:`inspect.ArgSpec`, i.e., a named tuple
 
     EXAMPLES::
 
@@ -1123,6 +1078,7 @@ def _sage_getargspec_from_ast(source):
         True
         sage: set(from_ast(sms.sage_getsource(x)) == inspect.getfullargspec(x) for x in [factor, identity_matrix, Graph.__init__])                              # needs sage.graphs sage.modules
         {True}
+
     """
     ast_args = ast.parse(source.lstrip()).body[0].args
 
@@ -1146,13 +1102,11 @@ def _sage_getargspec_cython(source):
 
     INPUT:
 
-    - ``source`` - a string; the function's (or method's) source code
+    - ``source`` -- a string; the function's (or method's) source code
       definition.  The function's body is ignored. The definition may
       contain type definitions for the function arguments.
 
-    OUTPUT:
-
-    - an instance of :class:`inspect.FullArgSpec`, i.e., a named tuple
+    OUTPUT: an instance of :class:`inspect.FullArgSpec`, i.e., a named tuple
 
     EXAMPLES::
 
@@ -1222,13 +1176,6 @@ def _sage_getargspec_cython(source):
                     defaults=('a string', {(1, 2, 3): True}),
                     kwonlyargs=[], kwonlydefaults=None, annotations={})
 
-
-    AUTHORS:
-
-    - Nick Alexander: original version
-    - Simon King (02-2013): recognise varargs and default values in
-      cython code, and return an ``ArgSpec``.
-
     """
     defpos = source.find('def ')
     assert defpos > -1, "The given source does not contain 'def'"
@@ -1352,7 +1299,9 @@ def sage_getfile(obj):
     r"""
     Get the full file name associated to ``obj`` as a string.
 
-    INPUT: ``obj``, a Sage object, module, etc.
+    INPUT:
+
+    - ``obj`` -- a Sage object, module, etc.
 
     EXAMPLES::
 
@@ -1395,10 +1344,6 @@ def sage_getfile(obj):
         sage: sage_getfile(range)
         ''
 
-    AUTHORS:
-
-    - Nick Alexander
-    - Simon King
     """
     # We try to extract from docstrings, but not using Python's inspect
     # because _sage_getdoc_unformatted is more robust.
@@ -1433,7 +1378,9 @@ def sage_getfile_relative(obj):
     if the source file is part of the ``sage.*`` namespace, it
     makes the file name relative so that it starts with ``sage/``.
 
-    INPUT: ``obj``, a Sage object, module, etc.
+    INPUT:
+
+    - ``obj`` -- a Sage object, module, etc.
 
     EXAMPLES::
 
@@ -1447,6 +1394,7 @@ def sage_getfile_relative(obj):
         'sage/symbolic/expression.pyx'
         sage: sage_getfile_relative(range)
         ''
+
     """
     filename = sage_getfile(obj)
     if not filename:
@@ -1669,12 +1617,6 @@ def foo(x, a='\')"', b={not (2+1==3):'bar'}): return
         sage: shell.run_cell('f??')
         ...the source code string...
 
-    AUTHORS:
-
-    - William Stein: a modified version of inspect.getargspec from the
-      Python Standard Library, which was taken from IPython for use in Sage.
-    - Extensions by Nick Alexander
-    - Simon King: Return an ``ArgSpec``, fix some bugs.
     """
     from sage.misc.lazy_attribute import lazy_attribute
     from sage.misc.abstract_method import AbstractMethod
@@ -1773,7 +1715,7 @@ def formatannotation(annotation, base_module=None):
     INPUT:
 
     - ``annotation`` -- annotation for a function
-    - ``base_module`` (optional, default ``None``)
+    - ``base_module``-- (optional, default ``None``)
 
     This is only relevant with Python 3, so the doctests are marked
     accordingly.
@@ -1895,8 +1837,8 @@ def sage_getdef(obj, obj_name=''):
 
     INPUT:
 
-    - ``obj`` - function
-    - ``obj_name`` - string (optional, default '')
+    - ``obj`` -- function
+    - ``obj_name`` -- string (optional, default '')
 
     ``obj_name`` is prepended to the output.
 
@@ -1915,11 +1857,6 @@ def sage_getdef(obj, obj_name=''):
 
     If an exception is generated, None is returned instead and the
     exception is suppressed.
-
-    AUTHORS:
-
-    - William Stein
-    - extensions by Nick Alexander
     """
     try:
         spec = sage_getargspec(obj)
@@ -1985,10 +1922,6 @@ def _sage_getdoc_unformatted(obj):
         sage: _sage_getdoc_unformatted(obj)
         ''
 
-    AUTHORS:
-
-    - William Stein
-    - extensions by Nick Alexander
     """
     if obj is None:
         return ''
@@ -2126,10 +2059,6 @@ def sage_getdoc(obj, obj_name='', embedded=False):
         sage: sage_getdoc(f1)
         'specialised documentation\n'
 
-    AUTHORS:
-
-    - William Stein
-    - extensions by Nick Alexander
     """
     import sage.misc.sagedoc
     if obj is None:
@@ -2170,11 +2099,6 @@ def sage_getsource(obj):
         'identity_matrix(ring, n=0, sparse=False):'
         sage: sage_getsource(identity_matrix)[19:60]                                    # needs sage.modules
         'identity_matrix(ring, n=0, sparse=False):'
-
-    AUTHORS:
-
-    - William Stein
-    - extensions by Nick Alexander
     """
     # First we should check if the object has a _sage_src_
     # method.  If it does, we just return the output from
@@ -2236,10 +2160,6 @@ class ParentMethods:
     has a docstring. Otherwise, the code of ``B`` could not be found (Cython
     inserts embedding information into the docstring) and thus the code of
     ``B.A`` couldn't be found either.
-
-    AUTHOR:
-
-    - Simon King (2011-09)
     """
     # First, split the name:
     if '.' in obj.__name__:
@@ -2347,26 +2267,30 @@ def sage_getsourcelines(obj):
     EXAMPLES::
 
         sage: from sage.misc.sageinspect import sage_getsourcelines
-        sage: from sage.matrix.constructor import matrix                                # needs sage.modules
-        sage: sage_getsourcelines(matrix)[1]                                            # needs sage.modules
+
+        sage: # needs sage.modules
+        sage: from sage.matrix.constructor import matrix
+        sage: sage_getsourcelines(matrix)[1]
         21
-        sage: sage_getsourcelines(matrix)[0][0]                                         # needs sage.modules
+        sage: sage_getsourcelines(matrix)[0][0]
         'def matrix(*args, **kwds):\n'
 
     Some classes customize this using a ``_sage_src_lines_`` method,
     which gives the source lines of a class instance, but not the class
     itself. We demonstrate this for :class:`CachedFunction`::
 
-        sage: cachedfib = cached_function(fibonacci)                                    # needs sage.combinat
-        sage: sage_getsourcelines(cachedfib)[0][0]                                      # needs sage.combinat
+        sage: # needs sage.combinat
+        sage: cachedfib = cached_function(fibonacci)
+        sage: sage_getsourcelines(cachedfib)[0][0]
         'def fibonacci(n, algorithm="pari") -> Integer:\n'
-        sage: sage_getsourcelines(type(cachedfib))[0][0]                                # needs sage.combinat
+        sage: sage_getsourcelines(type(cachedfib))[0][0]
         'cdef class CachedFunction():\n'
 
     TESTS::
 
-        sage: cython('''cpdef test_funct(x,y): return''')                               # needs sage.misc.cython
-        sage: sage_getsourcelines(test_funct)                                           # needs sage.misc.cython
+        sage: # needs sage.misc.cython
+        sage: cython('''cpdef test_funct(x,y): return''')
+        sage: sage_getsourcelines(test_funct)
         (['cpdef test_funct(x,y): return\n'], 1)
 
     The following tests that an instance of ``functools.partial`` is correctly
@@ -2444,14 +2368,6 @@ class Element():
           '    def __init__(self, ring, gens, coerce=True):\n',
           ...)
 
-    AUTHORS:
-
-    - William Stein
-    - Extensions by Nick Alexander
-    - Extension to interactive Cython code by Simon King
-    - Simon King: If a class has no docstring then let the class
-      definition be found starting from the ``__init__`` method.
-    - Simon King: Get source lines for dynamic classes.
     """
     # First try the method _sage_src_lines_(), which is meant to give
     # the source lines of an object (not of its type!).
@@ -2491,11 +2407,7 @@ class Element():
     pos = _extract_embedded_position(d)
     if pos is None:
         try:
-            # BEWARE HERE
-            # inspect gives str (=bytes) in python2
-            # and str (=unicode) in python3
             return inspect.getsourcelines(obj)
-
         except (OSError, TypeError) as err:
             try:
                 objinit = obj.__init__
diff --git a/src/sage_docbuild/conf.py b/src/sage_docbuild/conf.py
index 1c705c68d1f..99b7dfe0927 100644
--- a/src/sage_docbuild/conf.py
+++ b/src/sage_docbuild/conf.py
@@ -18,24 +18,23 @@
 # Load configuration shared with sage.misc.sphinxify
 from sage.misc.sagedoc_conf import *
 
-import importlib
 import sys
 import os
+import importlib
+import dateutil.parser
 import sphinx
 import sphinx.ext.intersphinx as intersphinx
-import dateutil.parser
-import sage.version
-
 from sphinx import highlighting
 from sphinx.transforms import SphinxTransform
 from IPython.lib.lexers import IPythonConsoleLexer, IPyLexer
-
 from sage.misc.sagedoc import extlinks
 from sage.env import SAGE_DOC_SRC, SAGE_DOC, PPLPY_DOCS, MATHJAX_DIR
 from sage.misc.latex_macros import sage_mathjax_macros
 from sage.features import PythonModule
 from sage.features.all import all_features
+import sage.version
 
+# ---------------------
 # General configuration
 # ---------------------
 
@@ -51,6 +50,7 @@
     'sphinx.ext.todo',
     'sphinx.ext.extlinks',
     'sphinx.ext.mathjax',
+    'sphinx.ext.linkcode',
     'sphinx_copybutton',
     'sphinx_inline_tabs',
     'IPython.sphinxext.ipython_directive',
@@ -198,6 +198,9 @@ def sphinx_plot(graphics, **kwds):
 version = sage.version.version
 release = sage.version.version
 
+source_repository = 'https://github.com/sagemath/sage/'
+source_branch = 'develop'
+
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 # language = None
@@ -255,6 +258,7 @@ def sphinx_plot(graphics, **kwds):
 # displaying all parents.
 toc_object_entries_show_parents = 'hide'
 
+# -----------------------
 # Extension configuration
 # -----------------------
 
@@ -313,73 +317,116 @@ def set_intersphinx_mappings(app, config):
 copybutton_exclude = '.linenos, .c1'  # exclude single comments (in particular, # optional!)
 copybutton_only_copy_prompt_lines = True
 
+
+# https://www.sphinx-doc.org/en/master/usage/extensions/linkcode.html
+def linkcode_resolve(domain, info):
+    import inspect
+    from urllib.parse import quote
+    from sage.misc.sageinspect import sage_getsourcelines
+    if domain != 'py':
+        return None
+    if info['module']:
+        m = importlib.import_module(info['module'])
+        filename = quote(info['module'].replace('.', '/'))
+        if m.__file__.endswith('py'):
+            filename += '.py'
+        else:
+            filename += '.pyx'
+        if 'fullname' in info:
+            fullname = info['fullname']
+            obj = m
+            try:
+                for attr in fullname.split('.'):
+                    obj = getattr(obj, attr)
+                lineno = sage_getsourcelines(obj)[-1]
+            except Exception:  # catch all
+                return None
+            anchor = f'#L{lineno}'
+        else:
+            anchor = ''
+        return f"{source_repository}blob/{version}/src/{filename}{anchor}"
+    return None
+
+
+# -----------------------
 # Options for HTML output
 # -----------------------
 
 # Add any paths that contain custom themes here, relative to this directory.
 html_theme_path = [os.path.join(SAGE_DOC_SRC, "common", "themes")]
 
-if PythonModule("furo").is_present():
-    # Sphinx theme "furo" does not permit an extension. Do not attempt to make
-    # a "sage-furo" theme.
-    html_theme = "furo"
-
-    # Theme options are theme-specific and customize the look and feel of
-    # a theme further.  For a list of options available for each theme,
-    # see the documentation.
-    html_theme_options = {
-        "light_css_variables": {
-            "color-brand-primary": "#0f0fff",
-            "color-brand-content": "#0f0fff",
-        },
-        "light_logo": "logo_sagemath_black.svg",
-        "dark_logo": "logo_sagemath_white.svg",
-    }
-
-    # The name of the Pygments (syntax highlighting) style to use. This
-    # overrides a HTML theme's corresponding setting.
-    pygments_style = "sphinx"
-    pygments_dark_style = "monokai"
-
-    # Add siderbar/home.html to the default sidebar.
-    html_sidebars = {
-        "**": [
-            "sidebar/scroll-start.html",
-            "sidebar/brand.html",
-            "sidebar/search.html",
-            "sidebar/home.html",
-            "sidebar/navigation.html",
-            "sidebar/ethical-ads.html",
-            "sidebar/scroll-end.html",
-            "sidebar/variant-selector.html",
-        ]
-    }
-
-    # These paths are either relative to html_static_path
-    # or fully qualified paths (eg. https://...)
-    html_css_files = [
-        'custom-furo.css',
-        'custom-jupyter-sphinx.css',
-        'custom-codemirror-monokai.css',
-    ]
+# Deprecated Sage classic theme:
+#
+#   html_theme = "sage-classic"
+#   html_theme_options = {}
+#
+# See the directory doc/common/themes/sage-classic/ for theme files.
+
+# Sphinx theme "furo" does not permit an extension. Do not attempt to make
+# a "sage-furo" theme.
+html_theme = "furo"
+
+# Theme options are theme-specific and customize the look and feel of
+# a theme further.  For a list of options available for each theme,
+# see the documentation.
+html_theme_options = {
+    "light_css_variables": {
+        "color-brand-primary": "#0f0fff",
+        "color-brand-content": "#0f0fff",
+    },
+    "light_logo": "logo_sagemath_black.svg",
+    "dark_logo": "logo_sagemath_white.svg",
+    # Furo can add a small edit button to each document to allow visitors to
+    # easily propose changes to that document using the repository’s source
+    # control system.
+    # https://pradyunsg.me/furo/customisation/edit-button/#adding-an-edit-button
+    "source_repository": source_repository,
+    "source_branch": source_branch,
+    # "source_directory" is defined in conf.py customized for the doc
+}
 
-    html_js_files = [
-        'jupyter-sphinx-furo.js',
+if not version.split('.')[-1].isnumeric():  # develop version
+    html_theme_options.update({
+        "announcement": f'This is documentation for Sage development version {version}. '
+                         'The documentation for the latest stable version is available '
+                         '<a href="https://doc.sagemath.org/html/en/index.html">here</a>.'
+})
+
+# The name of the Pygments (syntax highlighting) style to use. This
+# overrides a HTML theme's corresponding setting.
+pygments_style = "sphinx"
+pygments_dark_style = "monokai"
+
+# Add siderbar/home.html to the default sidebar.
+html_sidebars = {
+    "**": [
+        "sidebar/scroll-start.html",
+        "sidebar/brand.html",
+        "sidebar/search.html",
+        "sidebar/home.html",
+        "sidebar/navigation.html",
+        "sidebar/ethical-ads.html",
+        "sidebar/scroll-end.html",
+        "sidebar/variant-selector.html",
     ]
+}
 
-    # A list of paths that contain extra templates (or templates that overwrite
-    # builtin/theme-specific templates). Relative paths are taken as relative
-    # to the configuration directory.
-    templates_path = [os.path.join(SAGE_DOC_SRC, 'common', 'templates-furo')] + templates_path
+# These paths are either relative to html_static_path
+# or fully qualified paths (eg. https://...)
+html_css_files = [
+    'custom-furo.css',
+    'custom-jupyter-sphinx.css',
+    'custom-codemirror-monokai.css',
+]
 
-else:
-    # Sage default Sphinx theme.
-    #
-    # See the directory doc/common/themes/sage-classic/ for files comprising
-    # the custom theme.
-    html_theme = "sage-classic"
+html_js_files = [
+    'jupyter-sphinx-furo.js',
+]
 
-    html_theme_options = {}
+# A list of paths that contain extra templates (or templates that overwrite
+# builtin/theme-specific templates). Relative paths are taken as relative
+# to the configuration directory.
+templates_path = [os.path.join(SAGE_DOC_SRC, 'common', 'templates-furo')] + templates_path
 
 # HTML style sheet. This overrides a HTML theme's corresponding setting.
 # html_style = 'default.css'
@@ -438,7 +485,7 @@ def set_intersphinx_mappings(app, config):
 
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
-#html_last_updated_fmt = '%b %d, %Y'
+# html_last_updated_fmt = '%b %d, %Y'
 
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.
@@ -460,27 +507,29 @@ def set_intersphinx_mappings(app, config):
 modindex_common_prefix = ['sage.']
 
 # If false, no index is generated.
-#html_use_index = True
+# html_use_index = True
 
 # If true, the index is split into individual pages for each letter.
 html_split_index = True
 
 # If true, the reST sources are included in the HTML build as _sources/<name>.
-#html_copy_source = True
+# html_copy_source = True
 
 # If true, an OpenSearch description file will be output, and all pages will
 # contain a <link> tag referring to it.  The value of this option must be the
 # base URL from which the finished HTML is served.
-#html_use_opensearch = ''
+# html_use_opensearch = ''
 
 # If nonempty, this is the file name suffix for HTML files (e.g. ".xhtml").
-#html_file_suffix = ''
+# html_file_suffix = ''
 
 # Output file base name for HTML help builder.
-#htmlhelp_basename = ''
+# htmlhelp_basename = ''
 
+# ------------------------
 # Options for LaTeX output
 # ------------------------
+
 # See http://sphinx-doc.org/config.html#confval-latex_elements
 latex_elements = {}
 
@@ -523,13 +572,14 @@ def set_intersphinx_mappings(app, config):
 """
 
 # Documents to append as an appendix to all manuals.
-#latex_appendices = []
+# latex_appendices = []
 
 # If false, no module index is generated.
-#latex_use_modindex = True
+# latex_use_modindex = True
 
-#####################################################
+# -------------------------
 # add LaTeX macros for Sage
+# -------------------------
 
 from sage.misc.latex_macros import sage_latex_macros
 
@@ -544,8 +594,9 @@ def set_intersphinx_mappings(app, config):
     # used when building html version
     pngmath_latex_preamble += macro + '\n'
 
-#####################################################
+# ------------------------------------------
 # add custom context variables for templates
+# ------------------------------------------
 
 def add_page_context(app, pagename, templatename, context, doctree):
     # # The template function
@@ -569,6 +620,17 @@ def add_page_context(app, pagename, templatename, context, doctree):
         context['reference_title'] = 'Sage {}'.format(release) + ' Reference Manual'
         context['reference_root'] = os.path.join(relpath, 'index.html')
         context['refsub'] = True
+        if pagename.startswith('sage/'):
+            # This is for adding small edit button using Furo's feature:
+            # https://pradyunsg.me/furo/customisation/edit-button/#adding-an-edit-button
+            # This works well if the source file is '.rst' file. But the '.rst'
+            # files in the directory 'sage/' are generated by the Sphinx
+            # autodoc from the Python or Cython source files. Hence we teak
+            # here template context variables so that links to the correct
+            # source files are generated.
+            suffix = '.py' if importlib.import_module(pagename.replace('/','.')).__file__.endswith('.py') else '.pyx'
+            context['page_source_suffix'] = suffix
+            context['theme_source_edit_link'] = os.path.join(source_repository, f'blob/develop/src', '{filename}')
 
 
 dangling_debug = False
@@ -731,7 +793,6 @@ def nitpick_patch_config(app):
     '__builtin__',
 ]
 
-
 def check_nested_class_picklability(app, what, name, obj, skip, options):
     """
     Print a warning if pickling is broken for nested classes.