Pure CSS triangles in any direction using the border trick. Live preview, copy the CSS.
It uses the 'border trick': an element with zero width and height but thick borders renders each border as a trapezoid meeting at 45-degree diagonals. Make three borders transparent and one colored, and the colored one becomes a triangle. This tool writes that CSS for you.
A CSS triangle needs no extra HTTP request, scales crisply, and is trivial to recolor. It is the classic way to make speech-bubble tails, dropdown carets and tooltips arrows.
Yes. Besides the four cardinal directions, the generator includes the four diagonal (corner) triangles, which use two colored borders meeting at a corner.