/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/ is in numix-blue-gtk-theme 0.54.
This file is owned by root:root, with mode 0o755.
..
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_actionbar.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_base.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_button.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_calendar.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_choosers.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_entry.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_grid.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_infobar.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_menu.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_misc.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_notebook.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_osd.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_overshoot.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_progress.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_scrollbar.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_sidebar.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_spinner.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_toggle.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_toolbar.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_view.scss
/usr/share/themes/NumixBlue/gtk-3.20/scss/widgets/_window.scss