h1 {
  text-decoration: underline;
}

details, .filter-container, .sort-container {
  border-radius: 10px;
  border-style: solid;
  border-width: thin;
  margin: 5px;
  padding: 5px;
}

details:target {
  border-width: thick;
}

summary {
  /* hide the default details arrow */
  display: block;
}

.book-title a {
  text-decoration: none;
}

summary img {
  vertical-align: middle;
}

summary .collapse-marker::after {
  content: "►";
}

details[open] summary .collapse-marker::after  {
  content: "▼";
}

.thumbnail {
  max-width: 128px;
  max-height: 128px;
}

.thumbnail-cell {
  text-align: center;
  width: 128px;
}

.filter-container {
  display: flex;
  transition: border-width 0.5s;
}

.filter-container:focus-within {
  border-width: thick;
}

.filter-container input {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
}