#filters {
  display: inline;
  margin-top: 15px;
}

#filters > div {
  display: inline-block;
}

#filters > summary {
  display: block;
  margin-bottom: 15px;
}

#filters > summary::before {
  content: "[ + ]";
  font-size: 1.5em;
}

#filters[open] > summary::before {
  content: "[ - ]";
  font-size: 1.5em;
}