geometric pattern of octagon lines. contained with octagon, triangles, and lines with gradient changing

abstract backdrop background black changing contained decor decoration design element endless fabric funky geometric geometrical geometry gradient graphic graphical grid illustration lattice line linear lines modern monochrome mosaic octagon ornament ornate panel pattern periodic print recurring regular repeat retro shape simple square striped structure style stylish swatches template textile texture textured tile tiling triangles vector wallpaper white wrapping