Creates a triangle shape with pure CSS.

<div class="triangle"></div>

.triangle {
  width: 0;
  height: 0;
  border-top: 20px solid #333;
  border-left: 20px solid transparent;
  border-right: 20px solid transparent;
}

Explanation

• View this link for a detailed explanation.
• The color of the border is the color of the triangle. The side the triangle tip points corresponds to the opposite border-* property. For example, a color on border-top means the arrow points downward.
• Experiment with the px values to change the proportion of the triangle.

Browser support