how to hover on one element and affect another code example

Example 1: hover on one div affect another

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

//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: on hover display another div css

.showme {
  display: none;
}

.showhim:hover .showme {
  display: block;
}


<div class="showhim">HOVER ME
  <div class="showme">hai</div>
</div>