css hover on after element and change another code example

Example 1: how to change another element on hover

// If the cube is directly inside the container:
#container:hover > #cube { background-color: yellow; }

// If cube is next to (after containers closing tag) the container:
#container:hover + #cube { background-color: yellow; }

// If the cube is somewhere inside the container:
#container:hover #cube { background-color: yellow; }

// If the cube is a sibling of the container:
#container:hover ~ #cube { background-color: yellow; }

Example 2: css hover change other element

#container:hover > #cube { background-color: yellow; }