CSS style for displayed message polluted by Roundcube

[Robb]

When displaying a mail in Roundcube, it looks subtly different from the
version seen in a local mail program.

It is (partly?) caused by CSS styles defined by Roundcube and made visible
to the mail display, which causes changes to the styling.

For example, in skins/default/common.css there are definitions with no ID or class, like:

td, th, div, p, select, input, textarea
{

font-size: 12px;
font-family: inherit;

}

(and others)

This means that any <td> in the mail will be styled with font-size 12 px, whereas in HTML mail like:

<table style="font-size: 8pt;"><tr><td>text</td></tr></table>

the text should really be styled with font-size 8pt when the style space is not polluted.

[alec]

In 507876cf038f87953702e34596d14d7f57666ccd I removed style on td, th, div and p elements. The rest of issues can be reliably fixed only by opening a message in a separate iframe without Roundcube styles. That's why I'm marking this ticket as a duplicate of #1488821.