My suggestion:
1 - First you need to understand how obsidian works in the two modes: editor mode and preview mode. For example, for internal-link you need to target css code differently to edit or preview mode:
edit mode
.cm-s-obsidian span.cm-hmd-internal-link {
color :red;
}
preview mode
.markdown-preview-view .internal-link {
color: orange;
}
2 - Then, you need to identify an attribute selector to add a particular style to a specific internal-link. But I think that isn’t so easy in editor mode, because the internal-link isn’t a really link.
3 - Use View > Toggle Developer Tools to identify your target elements.