:root {
  --primary:       #3b82f6;
  --primary-dark:  #2563eb;
  --success:       #10b981;
  --error:         #ef4444;
  --ai-color:      #8b5cf6;
  --bg:            #f0f4f8;
  --card:          #ffffff;
  --text:          #1e293b;
  --text-muted:    #64748b;
  --border:        #e2e8f0;
  --freq-high:     #dc2626;   /* 高頻度・赤 */
  --freq-middle:   #d97706;   /* 中頻度・橙 */
  --freq-low:      #2563eb;   /* 低頻度・青 */
  --freq-none:     #94a3b8;   /* 出題なし・グレー */
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', Meiryo, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

/* ─── PTCore サイト共通ヘッダー ─── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--card);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 1px 4px rgba(0,0,0,.06);
}
.site-header-inner {
  max-width: 680px;
  margin: 0 auto;
  padding: 0 16px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.site-back-link {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: .82rem;
  font-weight: 600;
  color: var(--primary);
  text-decoration: none;
  padding: 4px 10px;
  border-radius: 6px;
  transition: background .15s;
}
.site-back-link:hover { background: #eff6ff; }
.site-back-link svg   { flex-shrink: 0; }

.site-header-title {
  font-size: .9rem;
  font-weight: 700;
  color: var(--text);
}

.site-logo-link {
  font-size: .9rem;
  font-weight: 900;
  text-decoration: none;
  letter-spacing: -.5px;
}
.site-logo-pt   { color: var(--primary); }
.site-logo-core { color: var(--text); }

/* ─── PTCore トップへ戻るボタン（結果画面）─── */
/* ─── データ一覧リンク（スタート画面）─── */
.btn-data-link {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  color: var(--text-muted);
  font-size: .85rem;
  font-weight: 600;
  text-decoration: none;
  padding: 8px 16px;
  border-radius: 8px;
  transition: color .15s, background .15s;
}
.btn-data-link:hover {
  color: var(--primary);
  background: #eff6ff;
}

.btn-back-top {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  width: 100%;
  padding: 11px 24px;
  border: 2px solid var(--border);
  border-radius: 10px;
  background: var(--card);
  color: var(--text-muted);
  font-size: .9rem;
  font-weight: 600;
  text-decoration: none;
  transition: border-color .15s, color .15s, background .15s;
}
.btn-back-top:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: #eff6ff;
}

/* ─── Screen ─── */
.screen {
  display: none;
  min-height: calc(100vh - 48px); /* site-header分を引く */
  padding: 20px 16px 40px;
}
.screen.active { display: flex; justify-content: center; }

.container {
  width: 100%;
  max-width: 600px;
}

.center-col {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
  padding-top: 40px;
}

/* ─── Card ─── */
.card {
  background: var(--card);
  border-radius: 16px;
  padding: 20px;
  box-shadow: 0 1px 4px rgba(0,0,0,0.08);
}

/* ─── Start Screen ─── */
.logo { font-size: 64px; line-height: 1; }
h1   { font-size: 2rem; font-weight: 800; color: var(--primary); }
.subtitle { color: var(--text-muted); }

.start-options {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.option-group { display: flex; flex-direction: column; gap: 6px; }

.label-sm {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--text-muted);
}

select {
  width: 100%;
  padding: 10px 12px;
  border: 2px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  background: white;
  cursor: pointer;
}

.label-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.toggle-btns { display: flex; gap: 6px; }
.btn-tiny {
  padding: 3px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: white;
  font-size: .75rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  transition: background .15s, color .15s;
}
.btn-tiny:hover { background: var(--primary); color: white; border-color: var(--primary); }

.checkbox-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}
.checkbox-label {
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 0.9rem;
  cursor: pointer;
}

/* ─── Buttons ─── */
.btn {
  padding: 12px 24px;
  border: none;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform .15s, box-shadow .15s, background .15s;
}
.btn-lg { width: 100%; padding: 16px; font-size: 1.05rem; border-radius: 12px; }

.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(59,130,246,.35);
}

.btn-ai {
  background: linear-gradient(135deg, #8b5cf6, #6366f1);
  color: #fff;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}
.btn-ai:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(139,92,246,.4);
}
.btn-ai:disabled { opacity: .65; cursor: wait; transform: none; box-shadow: none; }

/* ─── 国家試験情報ボタン ─── */
.btn-kokushi {
  background: linear-gradient(135deg, #0369a1, #0284c7);
  color: #fff;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 24px;
  border: none;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform .15s, box-shadow .15s;
}
.btn-kokushi:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(3,105,161,.4);
}
.btn-kokushi:disabled { opacity: .65; cursor: wait; transform: none; box-shadow: none; }

/* ─── Progress ─── */
.progress-bar   { margin-bottom: 18px; }
.progress-info  { display: flex; justify-content: space-between; margin-bottom: 6px; font-size: .85rem; font-weight: 600; color: var(--text-muted); }
.progress-track { height: 6px; background: var(--border); border-radius: 3px; overflow: hidden; }
.progress-fill  { height: 100%; background: var(--primary); border-radius: 3px; transition: width .4s ease; width: 0%; }

/* ─── Question Card ─── */
.question-card  { margin-bottom: 14px; }
.category-badge {
  display: inline-block;
  background: #e0f2fe;
  color: #0369a1;
  font-size: .72rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 20px;
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: 10px;
}
.question-card h2    { font-size: 1.5rem; font-weight: 800; margin-bottom: 2px; }
.muscle-reading      { font-size: .8rem; color: var(--text-muted); margin-bottom: 10px; }
.question-text       { color: var(--text-muted); font-size: .9rem; }

/* ─── Options ─── */
.options-list { display: flex; flex-direction: column; gap: 9px; margin-bottom: 14px; }

.option-btn {
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 13px 16px;
  text-align: left;
  font-size: .88rem;
  line-height: 1.45;
  cursor: pointer;
  transition: border-color .15s, background .15s;
  display: flex;
  gap: 10px;
  align-items: flex-start;
}
.option-btn:hover:not(:disabled) {
  border-color: var(--primary);
  background: #eff6ff;
}
.option-btn .opt-label {
  font-weight: 700;
  color: var(--primary);
  flex-shrink: 0;
  width: 20px;
}
.option-btn.correct  { background: #d1fae5; border-color: var(--success); color: #065f46; }
.option-btn.correct .opt-label { color: var(--success); }
.option-btn.wrong    { background: #fee2e2; border-color: var(--error);   color: #7f1d1d; }
.option-btn.wrong   .opt-label { color: var(--error); }
.option-btn:disabled { cursor: default; }

/* ─── Result Area ─── */
.result-area {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.result-badge {
  text-align: center;
  font-size: 1.3rem;
  font-weight: 800;
  padding: 10px;
  border-radius: 10px;
}
.result-badge.correct { background: #d1fae5; color: #065f46; }
.result-badge.wrong   { background: #fee2e2; color: #7f1d1d; }

.answer-row { display: flex; flex-direction: column; gap: 4px; }
.correct-answer-text { font-size: .9rem; line-height: 1.55; white-space: pre-wrap; }

/* ─── AI Explanation（後方互換） ─── */
.ai-explanation-area {
  background: #f0f9ff;
  border: 1px solid #bae6fd;
  border-radius: 12px;
  padding: 14px;
}
.ai-header {
  font-weight: 700;
  color: var(--ai-color);
  font-size: .85rem;
  display: flex;
  align-items: center;
  gap: 5px;
  margin-bottom: 8px;
}

/* ─── 国家試験情報ヘッダー ─── */
.kokushi-header {
  font-weight: 700;
  color: #0369a1;
  font-size: .88rem;
  display: flex;
  align-items: center;
  gap: 5px;
  margin-bottom: 10px;
  padding-bottom: 6px;
  border-bottom: 2px solid #bae6fd;
}

.ai-explanation-text {
  font-size: .85rem;
  line-height: 1.75;
  color: var(--text);
  white-space: pre-wrap;
}
.ai-loading { color: var(--text-muted); font-style: italic; }

/* ─── Final Result Screen ─── */
.result-emoji  { font-size: 64px; }
#screen-result h2 { font-size: 1.5rem; font-weight: 700; }

.final-score {
  font-size: 2.6rem;
  font-weight: 800;
  color: var(--primary);
  line-height: 1;
}
.score-sep   { color: var(--text-muted); }
.score-label { font-size: 1.1rem; color: var(--text-muted); }
.score-pct   { color: var(--text-muted); font-size: 1rem; }

.result-list { width: 100%; display: flex; flex-direction: column; gap: 8px; }
.result-item {
  background: var(--card);
  border-radius: 10px;
  padding: 11px 14px;
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: .875rem;
  box-shadow: 0 1px 3px rgba(0,0,0,.05);
}
.result-item-icon   { font-size: 1.1rem; flex-shrink: 0; }
.result-item-muscle { font-weight: 600; }
.result-item-answer { color: var(--text-muted); font-size: .8rem; margin-top: 2px; }

/* ─── 出題頻度フィルター ─── */
.freq-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 7px;
}
.freq-label {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  border-radius: 8px;
  border: 2px solid var(--border);
  cursor: pointer;
  transition: border-color .15s, background .15s;
  font-size: .85rem;
}
.freq-label:hover { background: #f8fafc; }
.freq-label input[type="checkbox"] { flex-shrink: 0; }

.freq-star { font-size: .9rem; font-weight: 700; flex-shrink: 0; }
.freq-text { color: var(--text-muted); font-size: .8rem; }

.freq-high   { border-color: #fca5a5; }
.freq-high   .freq-star { color: var(--freq-high); }
.freq-high   input:checked ~ .freq-star { color: var(--freq-high); }

.freq-middle { border-color: #fcd34d; }
.freq-middle .freq-star { color: var(--freq-middle); }

.freq-low    { border-color: #93c5fd; }
.freq-low    .freq-star { color: var(--freq-low); }

.freq-none   { border-color: var(--border); }
.freq-none   .freq-star { color: var(--freq-none); }

/* チェック済みで枠を強調 */
.freq-high:has(input:checked)   { background: #fff1f1; border-color: var(--freq-high); }
.freq-middle:has(input:checked) { background: #fffbeb; border-color: var(--freq-middle); }
.freq-low:has(input:checked)    { background: #eff6ff; border-color: var(--freq-low); }
.freq-none:has(input:checked)   { background: #f8fafc; border-color: #94a3b8; }

/* question-card の頻度バッジ */
.freq-badge {
  display: inline-block;
  font-size: .7rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 20px;
  margin-left: 6px;
  vertical-align: middle;
}
.freq-badge.high   { background: #fee2e2; color: var(--freq-high); }
.freq-badge.middle { background: #fef3c7; color: var(--freq-middle); }
.freq-badge.low    { background: #dbeafe; color: var(--freq-low); }
.freq-badge.none   { background: #f1f5f9; color: var(--freq-none); }

/* ─── Utility ─── */
.hidden { display: none !important; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}
.fade-in { animation: fadeIn .25s ease; }