a { pause:  500ms 0s }
b { pause:  0s 10s }
c { pause:  2.1s 10s }
d { pause: 10% 5% }
e { pause: 10% 10s }
f { pause: 10s 10% }
g { pause: 10% }
h { pause: 10s }
i { pause: 0s }
z { pause: inherit }