dfnpewk

Here’s what’s going on

1. border-collapse: separate (what your getCleanHtml enforces) causes each <td> to render its own full border, so adjacent cells show two borders side-by-side.
   That’s why the top and right borders of inner cells look thicker or differently colored — you’re actually seeing two overlapping lines.

2. When tables use border-collapse: separate;, borders between cells merge into one, eliminating double lines — but that also can create inconsistencies if cells have different border colors or widths.

3. Since your sanitizer replaces border-collapse: separate; with border-collapse: separate;, the table can no longer unify cell borders, and CSS rules for each <td> apply independently.