body {
  font-family: sans-serif;
  margin: 0;
  padding: 0;
}
.menu {
  list-style: none;
  display: flex;
  gap: 1rem;
  background: #333;
  padding: 1rem;
  margin-top:0;
}
.menu a {
  color: white;
  text-decoration: none;
}
main {
    padding:1rem;
}
.slot {
  border: 1px solid #ccc;
  padding: 1rem;
  margin: 1rem;
  margin-left:0;
}
.card-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  list-style: none;
  padding: 0;
}
.card {
  width: 40px;
  height: 60px;
  background: #eee;
  text-align: center;
  line-height: 60px;
  cursor: move;
  border: 1px solid #aaa;
}
.ghost {
  opacity: 0.4;
  background-color: #ccc;
}
.card.red {
  color: red;
}