This template uses TemplateStyles:

Template:Sticky header/styles.css (sandbox)

This sandbox is using ((sticky header)). I added some more table widths. Divs have been removed.

See: User:Timeshifter/Sandbox243. And: Template:Sticky header. And: Template:Sticky header/testcases.

Substituted ((sticky header)) for ((sticky header/sandbox))
Substituted sticky-header for sticky-header-multi

Test sticky-header (no caption)

Wikitable:

Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9	Header 10	Header 11	Header 12	Header 13
3	data	data	data	data	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	data	data	data	data	a

Wikitable wikitext:

((Sticky header))
{| class="wikitable sticky-header"
|-
! Header !! Header 2 !! Header 3 !! Header 4
! Header 5 !! Header 6 !! Header 7 !! Header 8
! Header 9 || Header 10 || Header 11 || Header 12 || Header 13
⫶
|}

Plain table:

Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9
3	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	a

Plain table wikitext:

((sticky header))
{| class="sticky-header"
|-
! Header !! Header 2 !! Header 3 !! Header 4
! Header 5 !! Header 6 !! Header 7 !! Header 8
! Header 9
⫶
|}

Test sticky-header (no caption). Narrower tables

Header	Header 2	Header 3
3	data	b
1	data	c
2	data	a

Plain table:

Header	Header 2	Header 3
3	data	b
1	data	c
2	data	a

Test sticky-header (caption)

Sticky first row.

Wikitable:

Caption
Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9
3	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	a

Wikitable wikitext:

((sticky header))
{| class="wikitable sticky-header"
|+ Caption
|-
! Header !! Header 2 !! Header 3 !! Header 4
! Header 5 !! Header 6 !! Header 7 !! Header 8
! Header 9
⫶
|}

Plain table:

Caption
Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9
3	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	a

Plain table wikitext:

((sticky header))
{| class="sticky-header"
|+ Caption
|-
! Header !! Header 2 !! Header 3 !! Header 4
! Header 5 !! Header 6 !! Header 7 !! Header 8
! Header 9
⫶
|}

Test sticky-header (sortable)

Sticky first row.

Wikitable:

Caption
Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9	Header 10	Header 11	Header 12	Header 13	Header 14	Header 15	Header 16
top	top	top	top	top	top	top	top	top	top	top	top	top	top	top	top
3	data	data	data	data	data	data	data	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	data	data	data	data	data	data	data	a
bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom

Wikitable wikitext:

((Sticky header))
{| class="wikitable sortable sticky-header"
|+ Caption
|-
! Header !! Header 2 !! Header 3 !! Header 4
! Header 5 !! Header 6 !! Header 7 !! Header 8
! Header 9 !! Header 10 !! Header 11 !! Header 12
! Header 13 !! Header 14 !! Header 15 
! class="unsortable" | Header 16
|- class="sorttop"
| top || top || top || top || top || top 
| top || top || top || top || top || top 
| top || top || top || top 
...
|- class="sortbottom"
| bottom || bottom || bottom || bottom || bottom || bottom
| bottom || bottom || bottom || bottom || bottom || bottom 
| bottom || bottom || bottom || bottom 
|}

Plain table:

Caption
Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9
top	top	top	top	top	top	top	top	top
3	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	a
bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom

Plain table wikitext:

((sticky header))
{| class="sortable sticky-header"
|+ Caption
|-
! Header !! Header 2 !! Header 3 !! Header 4
! Header 5 !! Header 6 !! Header 7 !! Header 8
! class="unsortable" | Header 9
|- class="sorttop"
| top || top || top || top || top
| top || top || top || top
⫶
|- class="sortbottom"
| bottom || bottom || bottom || bottom || bottom
| bottom || bottom || bottom || bottom
|}

Test sticky-header (sortable). Narrower tables

Caption
Header	Header 2	Header 3
top	top	top
3	data	b
1	data	c
2	data	a
bottom	bottom	bottom

Plain table:

Caption
Header	Header 2	Header 3
top	top	top
3	data	b
1	data	c
2	data	a
bottom	bottom	bottom

Test sticky-header. 2 rows. (sortable)

Sticky <thead> element.

Tracked in Phabricator
Task T6740

Tracked in Phabricator
Task T355492

Issues:

Nothing sticky if JavaScript disabled, which is used by sortable, currently the only way to move headers to the <thead> element.
Sticky sorttop rows, which sortable moves to the <thead> element after sorting.

Wikitable:

Caption
Header	Header group
Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9
top	top	top	top	top	top	top	top	top
3	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	a
bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom

Wikitable wikitext:

((sticky header))
{| class="wikitable sortable sticky-header"
|+ Caption
|-
! rowspan="2" | Header
! colspan="8" | Header group
|-
! Header 2 !! Header 3 !! Header 4 !! Header 5
! Header 6 !! Header 7 !! Header 8
! class="unsortable" | Header 9
|- class="sorttop"
| top || top || top || top || top
| top || top || top || top
⫶
|- class="sortbottom"
| bottom || bottom || bottom || bottom || bottom
| bottom || bottom || bottom || bottom
|}

Plain table:

Caption
Header	Header group
Header	Header 2	Header 3	Header 4	Header 5	Header 6	Header 7	Header 8	Header 9
top	top	top	top	top	top	top	top	top
3	data	data	data	data	data	data	data	b
1	data	data	data	data	data	data	data	c
2	data	data	data	data	data	data	data	a
bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom	bottom

Plain table wikitext:

((sticky header))
{| class="sortable sticky-header"
|+ Caption
|-
! rowspan="2" | Header
! colspan="8" | Header group
|-
! Header 2 !! Header 3 !! Header 4 !! Header 5
! Header 6 !! Header 7 !! Header 8
! class="unsortable" | Header 9
|- class="sorttop"
| top || top || top || top || top
| top || top || top || top
⫶
|- class="sortbottom"
| bottom || bottom || bottom || bottom || bottom
| bottom || bottom || bottom || bottom
|}

Test template static row numbers (sticky-header, no caption)

Uses ((static row numbers)) with adjusted wikitable borders.

No label:

Label:

Header
rank 1
rank 2
norank 1
norank 2
rank 3
rank 4

Test template static row numbers (sticky-header, caption)

Uses ((static row numbers)) with adjusted wikitable borders.

No label:

Label:

Caption
Header
rank 1
rank 2
norank 1
norank 2
rank 3
rank 4

Test template static row numbers (sticky-header, sortable)

Uses ((static row numbers)) with adjusted wikitable borders.

No label:

Label:

Caption
Header
top
top
rank 1
rank 2
norank 1
norank 2
rank 3
rank 4
bottom
bottom

Test template static row numbers. 2 rows. (sticky-header, sortable)

Uses ((static row numbers)) with adjusted wikitable borders.

No label:

Label:

Caption
Header group
Header	Header
top	top
top	top
rank 1	data
rank 2	data
norank 1	data
norank 2	data
rank 3	data
rank 4	data
bottom	bottom
bottom	bottom

Padding

Padding for testing purposes.

More