De or het nagelstyling?

The correct Dutch article is:

de nagelstyling

Rule Words ending in -ing: almost always de. See the rule

How to use nagelstyling

the nagelstylingde nagelstyling
this nagelstylingdeze nagelstyling
that nagelstylingdie nagelstyling
our nagelstylingonze nagelstyling
your nagelstylingjouw nagelstyling
every nagelstylingelke nagelstyling
which nagelstyling?welke nagelstyling?
a big nagelstyling / the big nagelstylingeen grote nagelstyling, de grote nagelstyling