[request] support of 'inherit'

[peteroconnor]

/*----  a standard css template ----*/
.h3 {
    font-size: 20px;
}

span {
    font-size: 12px;
}

/*---- customization ----*/
.customized {
    font-size: inherit;
}

<!---- html ---->
<h3> blah blah ... <span class="customized"> more blah </span> </h3> 

<!---- desired inline result, as interpreted by chrome ---->
<h3 style="font-size: 20px;"> blah blah ... <span style="font-size: 20px"> more blah </span> </h3>

<!---- current inline result by pynliner ---->
<h3 style="font-size: 20px;"> blah blah ... <span style="font-size: 12px"> more blah </span> </h3>

[peteroconnor]

The issue is not with 'inherit', but it is because the difficulty of customizing Twitter Bootstrap in some cases.

Need more tests to pin down the specific problem.