:root {
  --black: #111111;
  --white: #ffffff;
  --gray-light: #eeeeee;
  --gray-mid: #bbbbbb;
  --gray-dark: #555555;
  --green: #2e7d32;
  --green-text: #ffffff;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  touch-action: manipulation;
}

body {
  font-family: "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", -apple-system, sans-serif;
  background: var(--white);
  color: var(--black);
  line-height: 1.7;
  font-weight: 500;
}

.hidden {
  display: none !important;
}

.screen {
  height: 100vh;
  height: 100dvh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 48px 16px;
  overflow-y: auto;
}

#screen-start {
  align-items: center;
  position: relative;
}

#screen-quiz {
  padding-top: 110px;
}

.credit {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 16px;
  text-align: center;
  font-size: 11px;
  color: var(--gray-mid);
}

.credit a {
  color: var(--gray-dark);
}

.container {
  width: 100%;
  max-width: 640px;
}

.title {
  font-size: 24px;
  font-weight: 700;
  margin: 0 0 24px 0;
  border-bottom: 2px solid var(--black);
  padding-bottom: 12px;
  text-align: center;
}

.description {
  font-size: 14px;
  color: var(--gray-dark);
  margin: 0 0 32px 0;
  text-align: left;
}

/* ---------- ボタン ---------- */
.btn {
  display: block;
  width: 100%;
  padding: 14px 16px;
  font-size: 15px;
  font-weight: 500;
  font-family: inherit;
  border: 2px solid var(--black);
  border-radius: 0;
  background: var(--white);
  color: var(--black);
  cursor: pointer;
  margin-top: 16px;
  -webkit-tap-highlight-color: transparent;
}

@media (hover: hover) {
  .btn:hover {
    background: var(--gray-light);
  }
}

.btn-primary {
  background: var(--black);
  color: var(--white);
}

@media (hover: hover) {
  .btn-primary:hover {
    background: var(--gray-dark);
  }
}

.btn-secondary {
  background: var(--white);
  color: var(--black);
}

/* ---------- 問題画面 ---------- */
.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 12px;
  color: var(--gray-dark);
  border-bottom: 1px solid var(--gray-mid);
  padding-bottom: 8px;
  margin-bottom: 24px;
}

.quiz-timer {
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.5px;
}

.quiz-prompt {
  font-size: 19px;
  font-weight: 700;
  text-align: center;
  margin: 0 0 36px 0;
  min-height: 2.4em;
}

.tiles {
  display: flex;
  flex-wrap: nowrap;
  justify-content: center;
  align-items: center;
  gap: var(--tile-gap, 10px);
  margin-bottom: 36px;
  overflow-x: auto;
}

.tile {
  width: var(--tile-size, 60px);
  height: var(--tile-size, 60px);
  flex-shrink: 0;
  border: 2px solid var(--black);
  border-radius: 0;
  background: var(--white);
  color: var(--black);
  font-size: var(--tile-font-size, 26px);
  font-weight: 700;
  font-family: inherit;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

@media (hover: hover) {
  .tile:hover {
    background: var(--gray-light);
  }
}

.tile.selected {
  background: var(--black);
  color: var(--white);
}

.tile.correct {
  background: var(--green);
  color: var(--green-text);
  border-color: var(--green);
}

.tile:disabled {
  cursor: default;
}

.quiz-controls {
  display: flex;
  justify-content: center;
  gap: 12px;
}

.quiz-controls .btn {
  width: auto;
  min-width: 140px;
}

#btn-hint.active {
  background: var(--green);
  color: var(--green-text);
  border-color: var(--green);
}

/* ---------- 正解ボックス ---------- */
.result-box {
  margin-top: 32px;
  border-top: 2px solid var(--black);
  padding-top: 24px;
  text-align: center;
}

.answer-mark {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 4px;
  margin: 0 0 12px 0;
}

.answer-word {
  font-size: 22px;
  font-weight: 700;
  margin: 0 0 12px 0;
}

.answer-explanation {
  display: inline-block;
  max-width: 100%;
  font-size: 13px;
  color: var(--gray-dark);
  text-align: left;
  margin: 0 0 24px 0;
}

.answer-controls {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 16px;
}

.answer-controls .btn {
  width: auto;
  min-width: 140px;
  margin-top: 0;
}

/* ---------- 結果画面 ---------- */
.result-nohint {
  display: table;
  margin: 0 auto 16px auto;
  border: 2px solid var(--black);
  padding: 6px 16px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 2px;
  text-align: center;
}

.result-score {
  text-align: center;
  font-size: 16px;
  font-weight: 700;
  margin: 0 0 20px 0;
}

.result-time-label {
  text-align: center;
  font-size: 13px;
  color: var(--gray-dark);
  margin: 0 0 4px 0;
}

.result-time {
  text-align: center;
  font-size: 32px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  margin: 0 0 24px 0;
}

.review-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 32px;
  font-size: 13px;
}

.review-table th,
.review-table td {
  border: 1px solid var(--black);
  padding: 10px;
  text-align: left;
  vertical-align: top;
}

.review-table th {
  background: var(--black);
  color: var(--white);
  font-weight: 700;
}

.review-table th:first-child,
.review-table td.col-answer {
  width: 22%;
}

.review-table td.col-answer {
  font-weight: 700;
  white-space: nowrap;
}

/* ---------- 隠しトリガー ---------- */
.btn-secret-trigger {
  display: block;
  width: 36px;
  height: 10px;
  margin: 56px auto 0 auto;
  padding: 0;
  border: none;
  background: var(--white);
  cursor: pointer;
}

/* ---------- 全問題の一覧(隠しページ) ---------- */
.secret-overlay {
  position: fixed;
  inset: 0;
  background: rgba(17, 17, 17, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  z-index: 1000;
}

.secret-panel {
  width: 100%;
  max-width: 640px;
  height: 80vh;
  background: var(--white);
  border: 2px solid var(--black);
  padding: 20px;
  display: flex;
  flex-direction: column;
}

.secret-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 2px solid var(--black);
  padding-bottom: 12px;
  margin-bottom: 16px;
  flex-shrink: 0;
}

.secret-header h3 {
  margin: 0;
  font-size: 16px;
}

.btn-close {
  width: 28px;
  height: 28px;
  padding: 0;
  border: 2px solid var(--black);
  background: var(--white);
  color: var(--black);
  font-size: 14px;
  font-weight: 700;
  line-height: 1;
  cursor: pointer;
}

@media (hover: hover) {
  .btn-close:hover {
    background: var(--gray-light);
  }
}

.secret-toggle {
  display: block;
  width: 100%;
  flex-shrink: 0;
  text-align: left;
  padding: 10px 12px;
  margin-bottom: 12px;
  border: 2px solid var(--black);
  background: var(--white);
  color: var(--gray-dark);
  font-size: 13px;
  font-family: inherit;
  cursor: pointer;
}

@media (hover: hover) {
  .secret-toggle:hover {
    background: var(--gray-light);
  }
}

.secret-table-wrap {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
  border: 1px solid var(--gray-mid);
}

.secret-table {
  width: 100%;
  table-layout: fixed;
  border-collapse: collapse;
  font-size: 12px;
}

.secret-table th,
.secret-table td {
  border: 1px solid var(--black);
  padding: 8px;
  text-align: left;
  vertical-align: top;
  overflow-wrap: break-word;
}

.secret-table th {
  background: var(--black);
  color: var(--white);
  font-weight: 700;
}

.secret-table th:nth-child(1),
.secret-table td.col-answer {
  width: 9em;
  font-weight: 700;
}

.secret-table th:nth-child(2),
.secret-table td.col-reading {
  width: 16%;
  font-size: 11px;
}

.secret-table td.col-reading {
  color: var(--gray-dark);
}

@media (max-width: 480px) {
  .review-table {
    font-size: 12px;
  }

  .review-table th,
  .review-table td {
    padding: 6px;
  }

  .secret-panel {
    height: 90vh;
    padding: 14px;
  }

  /* 画面の高さに収まるよう、上下の余白・間隔を詰める */
  .screen {
    padding: 20px 16px;
  }

  #screen-quiz {
    padding-top: 24px;
  }

  .title {
    margin-bottom: 16px;
  }

  .description {
    margin-bottom: 20px;
  }

  .quiz-header {
    margin-bottom: 16px;
  }

  .quiz-prompt {
    margin-bottom: 20px;
    min-height: 0;
  }

  .tiles {
    margin-bottom: 20px;
  }

  .result-box {
    margin-top: 20px;
    padding-top: 16px;
  }

  .answer-mark {
    margin-bottom: 8px;
  }

  .answer-word {
    margin-bottom: 8px;
  }

  .answer-explanation {
    margin-bottom: 16px;
  }

  .answer-controls {
    margin-top: 12px;
  }

  .review-table {
    margin-top: 20px;
  }
}