The phrase "accent stripes" refers to thin lines or markings that are added to something like clothing, furniture, or objects to make them more attractive or to highlight certain parts. Full definition
The first thing that catches the eye is the red accent stripe on the upper grille and headlamps. (topspeed.com)
The shirt has a dark navy stripe so I opted to go with somewhat of a traditional look with this red tie that has blue and white accent stripes. (fashables.com)
I added a white clutch to accent the stripe in the pants and keep the look from being too boring. (lilmissjbstyle.com)