px	em	percent
5px	0.3125em	31.25%
6px	0.3750em	37.50%
7px	0.4375em	43.75%
8px	0.5000em	50.00%
9px	0.5625em	56.25%
10px	0.6250em	62.50%
11px	0.6875em	68.75%
12px	0.7500em	75.00%
13px	0.8125em	81.25%
14px	0.8750em	87.50%
15px	0.9375em	93.75%
16px	1.0000em	100.00%
17px	1.0625em	106.25%
18px	1.1250em	112.50%
19px	1.1875em	118.75%
20px	1.2500em	125.00%
21px	1.3125em	131.25%
22px	1.3750em	137.50%
23px	1.4375em	143.75%
24px	1.5000em	150.00%
25px	1.5625em	156.25%