body {
  font-family: "Segoe UI", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  line-height: 1.6;
  background-color: #fdfdfd;
  color: #333;
  margin: 2em;
  padding: 0;
}

h2 {
  font-size: 1.5em;
  border-bottom: 2px solid #999;
  padding-bottom: 0.3em;
  margin-bottom: 1em;
}

h3 {
  margin-top: 2em;
  font-size: 1.2em;
  color: #444;
}

.quiz-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 2em;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  background: #fff;
}

.quiz-table th, .quiz-table td {
  border: 1px solid #ddd;
  padding: 1em;
  text-align: left;
  vertical-align: top;
  width: 50%;
}

.quiz-table th {
  background-color: #f3f3f3;
  font-weight: bold;
  font-size: 1em;
  color: #222;
}

.quiz-table td {
  background-color: #fcfcfc;
}

.quiz-table strong {
  display: block;
  margin-bottom: 0.5em;
  font-size: 1.05em;
  color: #000;
}

.quiz-table button {
  padding: 0.4em 0.8em;
  margin: 0.5em 0.5em 0.5em 0;
  background-color: #0066cc;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-size: 0.9em;
}

.quiz-table button:hover {
  background-color: #004c99;
}

details summary {
  font-weight: bold;
  cursor: pointer;
  color: #333;
  margin-bottom: 0.5em;
}

details[open] summary {
  margin-bottom: 0.5em;
}

#finished-list {
  margin-top: 0.5em;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4em;
}

#finished-list button {
  background-color: #bbb;
  color: #fff;
  border-radius: 50%;
  border: none;
  width: 2em;
  height: 2em;
  font-weight: bold;
  cursor: pointer;
}

#finished-list button:hover {
  background-color: #999;
}