[css]드롭박스

초기 세팅

display: none;
position: absolute;
z-index: 1;

hover 시,
display: block;

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  padding: 12px 16px;
  z-index: 1;
}

.dropdown:hover .dropdown-content {
  display: block;
}

https://www.w3schools.com/css/tryit.asp?filename=trycss_dropdown_text