After much trial and error i found out this:
TLDR:
html.format.unformatted: does not format the tag itself nor the content
html.format.contentUnformatted: will format the tag but not the content
source (not very clear, imho): https://code.visualstudio.com/Docs/languages/html
Sample html code (not valid, i know, but irrelevant here):
<body>
<style class="foo" class="foo" class="foo" >
.foo {
background-image: 'bar.jpeg';
background-size: cover;
background-position-x: 50%;
background-position-y: 50%;
}
</style>
<div class="foo">
<div>
<div></div>
whatever
<div></div>
</div>
</div>
</body>
With this config:
{
"html.format.wrapAttributes": "force-expand-multiline",
//"html.format.contentUnformatted" : "style",
"html.format.unformatted": "style"
}
When we trigger an auto format on the sample html above, the STYLE TAG IS NOT formatted and the style tag content IS NOT changed.
With this config:
{
"html.format.wrapAttributes": "force-expand-multiline",
"html.format.contentUnformatted" : "style",
//"html.format.unformatted": "style"
}
When we trigger an auto format on the sample html above, the STYLE TAG IS formatted (spaces, ident, etc), the style tag content IS NOT changed.