<time-percentage> is specified as an allowable type, this means that the percentage resolves to a time and therefore can be used in a
50% +50% Optional plus sign -50% Negative percentages are not valid for all properties that accept percentages
50 % Space not allowed between the space and the percentage sign
12s Positive integer -456ms Negative integer 4.3ms Non-integer 14mS The unit is case-insensitive, although capital letters are not recommended. +0s Zero with a leading + and a unit -0ms Zero with a leading - and a unit
0 Although unitless zero is allowed for <length>s, it's invalid for <time>s. 12.0 This is a <number>, not a <time>, because it's missing a unit. 7 ms No space is allowed between the number and the unit.
|CSS Values and Units Module Level 3 (CSS Values 3)|
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