* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: #f4f6f8;
  font-family: "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", sans-serif;
  color: #333;
}

.container {
  width: 100%;
  max-width: 480px;
  margin: 24px;
  padding: 32px 28px;
  background-color: #ffffff;
  border-radius: 12px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
}

h1 {
  margin: 0 0 24px;
  font-size: 22px;
  text-align: center;
  color: #2c3e50;
}

.progress {
  margin-bottom: 12px;
  font-size: 14px;
  color: #888;
  text-align: right;
}

.question-text {
  margin: 0 0 20px;
  font-size: 18px;
  font-weight: bold;
  line-height: 1.5;
  color: #2c3e50;
}

.choices {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.choice-button {
  padding: 12px 16px;
  font-size: 15px;
  text-align: left;
  border: 1px solid #bcd3f7;
  border-radius: 8px;
  background-color: #eef4ff;
  color: #1c3d66;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.choice-button:hover:not(:disabled) {
  background-color: #dce9fd;
  border-color: #8fb4ec;
}

.choice-button:disabled {
  cursor: default;
}

.choice-button.correct {
  background-color: #e3f7e8;
  border-color: #4caf50;
  color: #256029;
}

.choice-button.incorrect {
  background-color: #fdeaea;
  border-color: #e57373;
  color: #a12727;
}

.feedback {
  min-height: 22px;
  margin: 16px 0 8px;
  font-size: 15px;
  font-weight: bold;
  text-align: center;
}

.feedback.correct {
  color: #2e7d32;
}

.feedback.incorrect {
  color: #c62828;
}

.next-button {
  display: block;
  width: 100%;
  margin-top: 16px;
  padding: 12px;
  font-size: 15px;
  font-weight: bold;
  color: #ffffff;
  background-color: #2f6fed;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.15s ease;
}

.next-button:hover:not(:disabled) {
  background-color: #2557c2;
}

.next-button:disabled {
  background-color: #a9c2e8;
  cursor: default;
}

.hidden {
  display: none;
}

#result-screen h2 {
  margin: 0 0 16px;
  text-align: center;
  color: #2c3e50;
}

.score-text {
  margin: 0 0 20px;
  font-size: 18px;
  text-align: center;
  color: #333;
}