passa il mouse su un div influisce su un altro
//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; }
fai azione al passaggio del mouse su un altro elemento
#container:hover ~ #cube { background-color: yellow; }
al passaggio del mouse mostra un altro div css
.showme {
display: none;
}
.showhim:hover .showme {
display: block;
}
<div class="showhim">HOVER ME
<div class="showme">hai</div>
</div>