For each input on the left, this table lists what happens when you pass it into a CSS property and retrieve its value back. The third column indicates whether the value was round-tripped faithfully.

Basic floats
'0.0001'	0.0001	pass
0.0001	0.0001	pass
'123456.123456'	123456	pass
'1234567.1234567'	1.23457e+06	pass
'12345678.12345678'	1.23457e+07	pass
Trailing zeros
'0.00100000'	0.001	pass
'0.001000001'	0.001	pass
'0.12345000001'	0.12345	pass
'0.12304567'	0.123046	pass
'0.12340567'	0.123406	pass
'0.12345067'	0.123451	pass
'0.12345607'	0.123456	pass
'0.12345670'	0.123457	pass
Repeating decimals
1/3	0.333333	pass
123 + 1/3	123.333	pass
13/99	0.131313	pass
123 + 13/99	123.131	pass
100/999	0.1001	pass
123 + 100/999	123.1	pass
Large numbers
12345678	1.23457e+07	pass
123456789	1.23457e+08	pass
1234567890	1.23457e+09	pass
12345678901	1.23457e+10	pass
123456789012	1.23457e+11	pass
1234567890123	1.23457e+12	pass
12345678901234	1.23457e+13	pass
123456789012345	1.23457e+14	pass
1234567890123456	1.23457e+15	pass
12345678901234567	1.23457e+16	pass
Weird numbers
Number.NaN	1.23457e+16	pass
1/0	1.23457e+16	pass
Math.sqrt(-1)	1.23457e+16	pass
1/0.9999	1.0001	pass
1/0.99999	1.00001	pass
1/0.999999	1	pass
1/0.9999999	1	pass
1/0.99999999	1	pass