/usr/lib/R/site-library/rgl/html/ is in r-cran-rgl 0.96.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/R/site-library/rgl/html/00Index.html
/usr/lib/R/site-library/rgl/html/R.css
/usr/lib/R/site-library/rgl/htmlwidgets/lib/
/usr/lib/R/site-library/rgl/htmlwidgets/lib/CanvasMatrix/
/usr/lib/R/site-library/rgl/htmlwidgets/lib/CanvasMatrix/CanvasMatrix.src.js
/usr/lib/R/site-library/rgl/htmlwidgets/lib/rglClass/
/usr/lib/R/site-library/rgl/htmlwidgets/lib/rglClass/rgl.css
/usr/lib/R/site-library/rgl/htmlwidgets/lib/rglClass/rglClass.src.js
/usr/lib/R/site-library/rgl/htmlwidgets/rglPlayer.js
/usr/lib/R/site-library/rgl/htmlwidgets/rglPlayer.yaml
/usr/lib/R/site-library/rgl/htmlwidgets/rglWebGL.js
/usr/lib/R/site-library/rgl/htmlwidgets/rglWebGL.yaml