#tinyCSStip Want to create a triangle with all edges equal in 4 simple #CSS declarations?
Such a triangle also has all vertex angles equal = (sum of angles in a triangle)/3 = 180°/3 = 60°
https://en.wikipedia.org/wiki/Sum_of_angles_of_a_triangle
Knowing its edge length a, its height is a·sin(60°).
Aspect ratio of the box
a/(a·sin(60°)) = 1/sin(60°)