Setting font size in webvtt without css styling?

Question

In an attempt to convert a ttml file into a webvtt file, I've been trying to set a font size in cues, but without css styling. For instance, instead of:

WEBVTT

STYLE
::cue {
  font-size: 80%
}

I would like to have the font size attribute to appear in the cues:

00:00:00.000 --> 00:00:4.000 font-size: 80%
This is sized at 80%

I've tried using size: 80%, but apparently that's unrelated to font size.

Is there any way this could be accomplished?

Thanks in advance

Answer 1

The settings that can be specified on the cue are specified at:

https://www.w3.org/TR/webvtt1/#cue-settings

and those that can be specified on text within the cure are at:

https://www.w3.org/TR/webvtt1/#caption-text

Font size is not one of them.