Generate pure CSS triangles — no images, no SVG. Pick direction, size and color, then copy the border-trick or clip-path code.
The classic CSS triangle uses an element with width:0; height:0 and colored borders. Because borders meet at 45° angles, making adjacent borders transparent reveals a triangle. This trick works in every browser without any images or SVG. The modern alternative is clip-path: polygon() — easier to read, supports gradients and background images, and scales freely. One caveat: clip-path clips the element's box but does not collapse its layout space, while the border trick produces a truly zero-size element. Choose the border method for tooltips and UI arrows, and clip-path for decorative shapes.