.spon-grid {
  display: block;
  position: fixed;
  bottom: 0px;
  left: 0px;
  height: auto;
  width: 100%;
  border-top: 1px solid black;
  text-align: center;
}

.spon {
  vertical-align: middle;
  display: inline-block;
  height: auto;
  max-width: 7em;
  padding: 0.1em;
  margin-left: auto;
  margin-right: auto;
  margin-top: auto;
  margin-bottom: auto;
}

@media (max-width: 800px) {
  .spon {
    max-width: 5em;
  }
}

@media (max-width: 300px) {
  .spon {
    max-width: 3em;
  }
}

.box-spon-lay {
  background-color: rgba(200,200,200,0.90);
  transition: color 0.3s;
}

body[dark] .spon {
  filter: brightness(80%) grayscale() ;
}

body[dark] .box-spon-lay {
  background-color: rgba(255,255,255,0.90);
}