I tried that method for a moment (code below), but it didn’t work out too well due to the initial text-indent and padding of the element it’s attached to. It doesn’t seem trivial to remove those. There might be a better way.
/* Add faux vertical lines & indentation levels */
*[style*='text-indent:-3']:before {
content: '| ';
}
*[style*='text-indent:-4']:before {
content: '| | ';
}
*[style*='text-indent:-6']:before {
content: '| | | ';
}
*[style*='text-indent:']:before {
opacity: 0.3;
}
/* Hide existing indentation...? */
*[style*='text-indent:'] {
}