CSS Generated content for pseudo-elements

Method of displaying text or images before or after the given element's contents using the ::before and ::after pseudo-elements. All browsers with support also support the attr() notation in the content property.

Spec	https://www.w3.org/TR/CSS21/generate.html
Status	W3C Recommendation

IE	Edge	Firefox	Chrome	Safari	Opera
			108
		107	107	TP
		106	106	16.1
11	105	105	105	16.0	91
10	104	104	104	15.6	90
9	103	103	103	15.5	89
8 (1)	102	102	102	15.4	88
Show all
7	101	101	101	15.2-15.3	87
6	100	100	100	15.1	86
5.5	99	99	99	15	85
	98	98	98	14.1	84
	97	97	97	14	83
	96	96	96	13.1	82
	95	95	95	13	81
	94	94	94	12.1	80
	93	93	93	12	79
	92	92	92	11.1	78
	91	91	91	11	77
	90	90	90	10.1	76
	89	89	89	10	75
	88	88	88	9.1	74
	87	87	87	9	73
	86	86	86	8	72
	85	85	85	7.1	71
	84	84	84	7	70
	83	83	83	6.1	69
	81	82	81	6	68
	80	81	80	5.1	67
	79	80	79	5	66
	18	79	78	4	65
	17	78	77	3.2	64
	16	77	76	3.1	63
	15	76	75		62
	14	75	74		60
	13	74	73		58
	12	73	72		57
		72	71		56
		71	70		55
		70	69		54
		69	68		53
		68	67		52
		67	66		51
		66	65		50
		65	64		49
		64	63		48
		63	62		47
		62	61		46
		61	60		45
		60	59		44
		59	58		43
		58	57		42
		57	56		41
		56	55		40
		55	54		39
		54	53		38
		53	52		37
		52	51		36
		51	50		35
		50	49		34
		49	48		33
		48	47		32
		47	46		31
		46	45		30
		45	44		29
		44	43		28
		43	42		27
		42	41		26
		41	40		25
		40	39		24
		39	38		23
		38	37		22
		37	36		21
		36	35		20
		35	34		19
		34	33		18
		33	32		17
		32	31		16
		31	30		15
		30	29		12.1
		29	28		12
		28	27		11.6
		27	26		11.5
		26	25		11.1
		25	24		11
		24	23		10.6
		23	22		10.5
		22	21		10.0-10.1
		21	20		9.5-9.6
		20	19		9
		19	18
		18	17
		17	16
		16	15
		15	14
		14	13
		13	12
		12	11
		11	10
		10	9
		9	8
		8	7
		7	6
		6	5
		5	4
		4
		3.6
		3.5
		3
		2

Safari on iOS	Opera Mini	Android Browser	Blackberry Browser	Opera Mobile	Android Chrome	Android Firefox	IE Mobile	Android UC Browser	Samsung Internet	QQ Browser	Baidu Browser	KaiOS Browser
16.1
16.0	all	105	10	64	105	104	11	13.4	18.0	13.1	13.18	2.5
15.6		4.4.3-4.4.4	7	12.1			10		17.0
15.5		4.4		12					16.0
15.4		4.2-4.3		11.5					15.0
Show all
15.2-15.3		4.1		11.1					14.0
15.0-15.1		4		11					13.0
14.5-14.8		3		10					12.0
14.0-14.4		2.3							11.1-11.2
13.4-13.7		2.2							10.1
13.3		2.1							9.2
13.2									8.2
13.0-13.1									7.2-7.4
12.2-12.5									6.2-6.4
12.0-12.1									5.0-5.4
11.3-11.4									4
11.0-11.2
10.3
10.0-10.2
9.3
9.0-9.2
8.1-8.4
8
7.0-7.1
6.0-6.1
5.0-5.1
4.2-4.3
4.0-4.1
3.2

Notes

For content to appear in pseudo-elements, the content property must be set (but may be an empty string).

1. IE8 only supports the single-colon CSS 2.1 syntax (i.e. :pseudo-class). It does not support the double-colon CSS3 syntax (i.e. ::pseudo-element).

Bugs

• Chrome supports CSS transitions on generated content as of v. 26. Safari v6 and below do not support transitions or animations on pseudo elements.

• IE9, IE10, IE11 ignore CSS rem units in the line-height property. Bug report.

• Firefox & Edge do not support :after and :before for input fields

Resources

• Guide on usage
• Dev.Opera article
• WebPlatform Docs