:root {
  --bg: #ffffff;
  --bg-card: #f8fafc;
  --bg-code: #1e293b;
  --text: #1e3a5f;
  --text-muted: #64748b;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-light: #dbeafe;
  --success: #16a34a;
  --success-bg: #dcfce7;
  --error: #dc2626;
  --error-bg: #fee2e2;
  --warning-bg: #fef3c7;
  --warning-text: #92400e;
  --border: #cbd5e1;
  --header-bg: #1e3a5f;
  --header-text: #ffffff;
  --btn-radius: 0.5rem;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
  --safe-top: env(safe-area-inset-top, 0px);
  --safe-right: env(safe-area-inset-right, 0px);
  --safe-left: env(safe-area-inset-left, 0px);
  --header-base-height: 3.25rem;
  --header-total-height: calc(var(--header-base-height) + var(--safe-top));
}

[data-theme="cool"] {
  --bg: #0a0a0f;
  --bg-card: #14141f;
  --bg-code: #0d1117;
  --text: #e0f2fe;
  --text-muted: #67e8f9;
  --accent: #00ff88;
  --accent-hover: #00cc6a;
  --accent-light: #064e3b;
  --success: #00ff88;
  --success-bg: #064e3b;
  --error: #ff4466;
  --error-bg: #450a0a;
  --warning-bg: #1a1a2e;
  --warning-text: #00ff88;
  --border: #2d2d44;
  --header-bg: #0d1117;
  --header-text: #00ff88;
  --btn-radius: 0.375rem;
  --shadow: 0 0 20px rgb(0 255 136 / 0.15);
}

[data-theme="pop"] {
  --bg: #fff8f0;
  --bg-card: #ffffff;
  --bg-code: #4a3728;
  --text: #5c4033;
  --text-muted: #8b6914;
  --accent: #ff8c42;
  --accent-hover: #e6732f;
  --accent-light: #ffe4cc;
  --success: #7cb342;
  --success-bg: #e8f5e9;
  --error: #e53935;
  --error-bg: #ffebee;
  --warning-bg: #fff9c4;
  --warning-text: #f57f17;
  --border: #ffd699;
  --header-bg: #ff8c42;
  --header-text: #ffffff;
  --btn-radius: 1rem;
  --shadow: 0 4px 12px rgb(255 140 66 / 0.25);
}

* { box-sizing: border-box; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", sans-serif;
  min-height: 100dvh;
  overflow-x: hidden;
  transition: background 0.3s, color 0.3s;
}

.themed-header {
  position: fixed !important;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background: var(--header-bg);
  color: var(--header-text);
  min-height: var(--header-total-height);
  padding-top: calc(0.75rem + var(--safe-top));
  padding-right: calc(1rem + var(--safe-right));
  padding-bottom: 0.75rem;
  padding-left: calc(1rem + var(--safe-left));
}

.themed-header > * {
  min-width: 0;
}

.header-brand {
  flex: 1 1 auto;
}

.app-title {
  min-width: 0;
  font-size: 1.05rem;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.header-back-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 auto;
  position: relative;
  width: 2.4rem;
  height: 2.4rem;
  border: 1px solid rgba(255,255,255,0.35);
  border-radius: 999px;
  background: rgba(255,255,255,0.12);
  color: var(--header-text);
  font-size: 0;
  text-decoration: none;
  transition: background 0.2s, transform 0.1s;
}

.header-back-btn::before {
  content: "";
  width: 0.58rem;
  height: 0.58rem;
  border-left: 3px solid currentColor;
  border-bottom: 3px solid currentColor;
  transform: rotate(45deg);
  margin-left: 0.18rem;
}

.header-back-btn:active {
  transform: scale(0.94);
}

.header-back-btn:hover {
  background: rgba(255,255,255,0.22);
}

.themed-header + main {
  padding-top: calc(var(--header-total-height) + 1rem) !important;
}

.themed-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--btn-radius);
  box-shadow: var(--shadow);
}

.themed-btn-primary {
  background: var(--accent);
  color: #fff;
  border-radius: var(--btn-radius);
  transition: background 0.2s, transform 0.1s;
}
[data-theme="cool"] .themed-btn-primary { color: #0a0a0f; }
.themed-btn-primary:active { transform: scale(0.97); }
.themed-btn-primary:hover { background: var(--accent-hover); }

.themed-btn-secondary {
  background: var(--bg-card);
  color: var(--text);
  border: 2px solid var(--border);
  border-radius: var(--btn-radius);
  transition: all 0.2s;
}
.themed-btn-secondary.selected {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 700;
}
[data-theme="cool"] .themed-btn-secondary.selected { color: var(--accent); }

.themed-text-muted { color: var(--text-muted); }

.code-block {
  background: var(--bg-code);
  color: #e2e8f0;
  font-family: "Consolas", "Monaco", "Courier New", monospace;
  display: block;
  max-width: 100%;
  font-size: 0.85rem;
  line-height: 1.6;
  padding: 1rem;
  border-radius: var(--btn-radius);
  overflow-x: auto;
  white-space: pre;
  -webkit-overflow-scrolling: touch;
}
[data-theme="cool"] .code-block { color: #00ff88; border: 1px solid #2d2d44; }
[data-theme="pop"] .code-block { color: #fff8f0; }

.warning-box {
  background: var(--warning-bg);
  color: var(--warning-text);
  border-radius: var(--btn-radius);
  font-size: 0.8rem;
  padding: 0.6rem 0.75rem;
}

.choice-btn {
  display: flex;
  align-items: flex-start;
  gap: 0.55rem;
  min-height: 3.25rem;
  padding: 0.875rem 1rem;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--btn-radius);
  border: 2px solid var(--border);
  background: var(--bg-card);
  color: var(--text);
  transition: all 0.15s;
  word-break: break-word;
  text-align: left;
}
.choice-label {
  flex: 0 0 1.65rem;
  font-weight: 800;
  text-align: right;
}
.choice-text {
  min-width: 0;
  white-space: pre-wrap;
}
.choice-btn-code {
  font-family: "Consolas", "Monaco", "Courier New", monospace;
  font-size: 0.82rem;
  font-weight: 500;
  line-height: 1.55;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.choice-btn-code .choice-text {
  flex: 1 0 max-content;
  white-space: pre;
  word-break: normal;
  overflow-wrap: normal;
}
.choice-btn:active:not(:disabled) { transform: scale(0.98); }
.choice-btn:disabled { cursor: default; }
.choice-btn.correct {
  background: var(--success-bg) !important;
  border-color: var(--success) !important;
  color: var(--success) !important;
}
.choice-btn.wrong {
  background: var(--error-bg) !important;
  border-color: var(--error) !important;
  color: var(--error) !important;
}

.feedback-ok {
  background: var(--success-bg);
  color: var(--success);
  border: 2px solid var(--success);
  border-radius: var(--btn-radius);
  animation: popIn 0.3s ease;
}
.feedback-ng {
  background: var(--error-bg);
  color: var(--error);
  border: 2px solid var(--error);
  border-radius: var(--btn-radius);
  animation: shake 0.4s ease;
}

@keyframes popIn {
  0% { transform: scale(0.8); opacity: 0; }
  60% { transform: scale(1.05); }
  100% { transform: scale(1); opacity: 1; }
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(4px); }
}

details.explanation {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--btn-radius);
  overflow: hidden;
}
details.explanation summary {
  padding: 0.875rem 1rem;
  cursor: pointer;
  font-weight: 700;
  color: var(--accent);
  list-style: none;
  user-select: none;
}
details.explanation summary::-webkit-details-marker { display: none; }
details.explanation .explanation-body {
  padding: 1rem 1.15rem 1.15rem;
  font-size: 0.95rem;
  line-height: 1.9;
  color: var(--text);
  border-top: 1px solid var(--border);
  min-height: 5.5rem;
}

.header-quiz-actions {
  display: none;
}

.header-quiz-action-btn {
  border: 1px solid rgba(255,255,255,0.35);
  border-radius: var(--btn-radius);
  background: rgba(255,255,255,0.16);
  color: inherit;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 0.45rem 0.8rem;
  white-space: nowrap;
}

.header-quiz-action-btn:hover {
  background: rgba(255,255,255,0.28);
}

.header-stats {
  display: none;
  border: 1px solid rgba(255,255,255,0.35);
  border-radius: 9999px;
  background: rgba(255,255,255,0.16);
  color: inherit;
  font-size: 0.72rem;
  font-weight: 800;
  padding: 0.35rem 0.65rem;
  white-space: nowrap;
}

body.is-quiz-screen .header-stats {
  display: none;
}

body.is-quiz-screen .header-stats.has-score {
  display: block;
}

@media (max-width: 767px) {
  :root {
    --header-base-height: 3.75rem;
  }

  .themed-header {
    gap: 0.5rem;
    padding-top: calc(1.15rem + var(--safe-top));
    padding-bottom: 0.65rem;
  }

  .themed-header > .flex:first-child {
    flex: 1 1 auto;
    max-width: 58vw;
  }

  .themed-header > .header-brand {
    max-width: 100%;
  }

  body.is-quiz-screen .themed-header > .flex:first-child {
    max-width: 36vw;
  }

  .app-title {
    font-size: 0.98rem;
    letter-spacing: 0.01em;
  }

  .header-back-btn {
    width: 2.25rem;
    height: 2.25rem;
  }

  .header-stats {
    max-width: 22vw;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: 0.78rem;
    padding: 0.32rem 0.58rem;
    text-align: center;
  }

  .header-quiz-action-btn {
    max-width: 34vw;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: 0.72rem;
    padding: 0.38rem 0.55rem;
  }
}

.pattern-badge {
  font-size: 0.7rem;
  padding: 0.2rem 0.5rem;
  border-radius: 9999px;
  background: var(--accent-light);
  color: var(--accent);
  font-weight: 700;
}

.progress-bar {
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.3s;
}

body.is-quiz-screen .quiz-progress {
  position: fixed;
  top: var(--header-total-height);
  left: 0;
  right: 0;
  z-index: 45;
  margin: 0;
  border-radius: 0;
}

body.is-quiz-screen #screen-quiz {
  padding-top: calc(4px + 3.85rem);
}

.quiz-prompt {
  color: var(--text);
  line-height: 1.7;
}

.theme-option-card {
  display: flex;
  align-items: flex-start;
  gap: 0.9rem;
  width: 100%;
  padding: 1rem;
  text-align: left;
  transition: transform 0.15s, border-color 0.15s;
}

.theme-option-card:active {
  transform: scale(0.98);
}

.theme-option-card.selected {
  border-color: var(--accent);
  outline: 3px solid var(--accent-light);
}

.theme-option-icon {
  display: grid;
  place-items: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--btn-radius);
  background: var(--accent-light);
  color: var(--accent);
  font-size: 1.3rem;
  flex: 0 0 auto;
}

.theme-option-body {
  display: grid;
  gap: 0.25rem;
}

.theme-option-title {
  color: var(--text);
  font-size: 1rem;
  font-weight: 800;
}

.theme-option-desc {
  color: var(--text-muted);
  font-size: 0.85rem;
  line-height: 1.6;
}

.notation-nav {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.5rem;
  max-width: 100%;
  overflow: hidden;
}

.notation-nav a {
  border: 1px solid var(--border);
  border-radius: var(--btn-radius);
  color: var(--text);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 0.55rem 0.65rem;
  text-decoration: none;
}

.notation-nav a:active {
  transform: scale(0.98);
}

.notation-grid {
  display: grid;
  gap: 1rem;
  max-width: 100%;
  overflow: hidden;
}

.notation-card {
  min-width: 0;
  max-width: 100%;
  padding: 1rem;
  scroll-margin-top: 4.5rem;
}

.notation-card .code-block {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.notation-card h2 {
  color: var(--text);
  font-size: 1.05rem;
  font-weight: 800;
  margin-bottom: 0.45rem;
}

.notation-card p {
  color: var(--text);
  font-size: 0.9rem;
  line-height: 1.7;
  margin-bottom: 0.75rem;
}

.notation-run-btn {
  margin-top: 0.75rem;
  padding: 0.65rem 0.9rem;
  font-size: 0.9rem;
  font-weight: 800;
}

.notation-output {
  display: none;
  margin-top: 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--btn-radius);
  background: var(--accent-light);
  color: var(--text);
  font-family: "Consolas", "Monaco", "Courier New", monospace;
  font-size: 0.82rem;
  line-height: 1.7;
  padding: 0.75rem;
  white-space: pre-wrap;
  overflow-x: auto;
}

.notation-output.show {
  display: block;
}

.algorithm-card {
  display: grid;
  gap: 0;
  padding: 0;
  overflow: hidden;
}

.algorithm-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 1rem;
  color: var(--text);
  cursor: pointer;
  font-size: 1rem;
  font-weight: 800;
  list-style: none;
  user-select: none;
}

.algorithm-summary::-webkit-details-marker {
  display: none;
}

.algorithm-summary::after {
  content: "＋";
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 1.65rem;
  height: 1.65rem;
  border-radius: 999px;
  background: var(--accent-light);
  color: var(--accent);
  font-size: 1rem;
  font-weight: 900;
}

.algorithm-card[open] .algorithm-summary {
  border-bottom: 1px solid var(--border);
}

.algorithm-card[open] .algorithm-summary::after {
  content: "－";
}

.algorithm-detail {
  display: grid;
  gap: 0.8rem;
  padding: 1rem;
}

.algorithm-meta {
  display: grid;
  gap: 0.35rem;
  padding: 0.75rem;
  border-radius: var(--btn-radius);
  background: var(--accent-light);
  color: var(--text);
  font-size: 0.85rem;
  line-height: 1.7;
}

.algorithm-output {
  padding: 0.65rem 0.75rem;
  border-radius: var(--btn-radius);
  background: var(--success-bg);
  color: var(--success);
  font-size: 0.9rem;
  font-weight: 800;
  line-height: 1.6;
}

.algorithm-flow {
  display: grid;
  gap: 0.45rem;
  margin: 0;
  padding-left: 1.25rem;
  color: var(--text);
  font-size: 0.88rem;
  line-height: 1.7;
}

@media (min-width: 900px) {
  .notation-nav {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }

  .notation-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    align-items: start;
  }

  .notation-card .code-block {
    max-height: none;
  }
}

body.is-quiz-screen .quiz-actions {
  position: fixed;
  top: calc(var(--header-total-height) + 4px);
  left: 0;
  right: 0;
  z-index: 40;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  margin: 0;
  padding: 0.5rem calc(1rem + var(--safe-right)) 0.5rem calc(1rem + var(--safe-left));
}

@media (min-width: 768px) {
  body.is-quiz-screen .header-quiz-actions {
    display: flex;
    gap: 0.45rem;
    margin-left: auto;
  }

  body.is-quiz-screen .quiz-actions {
    display: none;
  }

  body.is-quiz-screen #screen-quiz {
    padding-top: 0;
  }
}

@media (min-width: 900px) {
  body.is-quiz-screen .app-shell {
    max-width: 1120px;
  }

  .quiz-actions {
    position: static;
    background: transparent;
    border-bottom: 0;
    max-width: 420px;
    margin-left: auto;
    padding: 0;
  }

  body.is-quiz-screen #screen-quiz {
    padding-top: 0;
  }

  body.is-quiz-screen .quiz-progress {
    position: static;
    margin: 0;
    border-radius: 2px;
  }

  .quiz-desktop-grid {
    display: block;
  }

  .quiz-main-pane,
  .quiz-side-pane {
    min-width: 0;
  }

  .code-block {
    max-height: 34dvh;
    font-size: 0.9rem;
    overflow: auto;
  }

  .choice-btn {
    min-height: 2.9rem;
    padding: 0.7rem 0.85rem;
  }

  .choice-btn-code {
    font-size: 0.78rem;
  }

  details.explanation .explanation-body {
    max-height: 28dvh;
    overflow-y: auto;
  }
}

.admin-label {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 700;
}

.admin-select {
  width: 100%;
  min-height: 2.75rem;
  border: 2px solid var(--border);
  border-radius: var(--btn-radius);
  background: var(--bg-card);
  color: var(--text);
  padding: 0 0.75rem;
  font-size: 0.95rem;
}

.admin-summary-card {
  padding: 0.75rem;
  text-align: center;
}

.admin-question-card {
  padding: 1rem;
}

.admin-badge {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 9999px;
  color: var(--text-muted);
  font-size: 0.7rem;
  font-weight: 700;
  padding: 0.2rem 0.5rem;
}

.admin-prompt {
  color: var(--text);
  font-size: 0.9rem;
  line-height: 1.7;
}

.admin-code {
  font-size: 0.8rem;
  margin-bottom: 0;
}

.admin-details {
  border-top: 1px solid var(--border);
  color: var(--text);
}

.admin-details summary {
  color: var(--accent);
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 700;
  padding-top: 0.75rem;
  user-select: none;
}

.admin-choice-list {
  display: grid;
  gap: 0.5rem;
  list-style: none;
  padding: 0;
}

.admin-choice-list li {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  border: 1px solid var(--border);
  border-radius: var(--btn-radius);
  font-size: 0.85rem;
  line-height: 1.6;
  padding: 0.6rem 0.7rem;
}

.admin-choice-label {
  flex: 0 0 1.65rem;
  font-weight: 800;
  text-align: right;
}

.admin-choice-text {
  min-width: 0;
  white-space: pre-wrap;
}

.admin-choice-code .admin-choice-text {
  font-family: "Consolas", "Monaco", "Courier New", monospace;
  font-size: 0.8rem;
  line-height: 1.55;
  flex: 1 0 max-content;
  white-space: pre;
  word-break: normal;
  overflow-wrap: normal;
}

.admin-choice-code {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.admin-choice-correct {
  background: var(--success-bg);
  border-color: var(--success) !important;
  color: var(--success);
}

.admin-explanation {
  background: var(--accent-light);
  border-radius: var(--btn-radius);
  color: var(--text);
  font-size: 0.85rem;
  line-height: 1.7;
  padding: 0.75rem;
}

.hidden { display: none !important; }