:root {
  --color-bg: #f4f6f8;
  --color-surface: #ffffff;
  --color-text: #1b2430;
  --color-text-muted: #5a6472;
  --color-primary: #145da0;
  --color-primary-dark: #0d3f70;
  --color-primary-contrast: #ffffff;
  --color-secondary: #eef2f6;
  --color-border: #dde3ea;
  --color-correct: #1a8754;
  --color-correct-bg: #e6f6ee;
  --color-wrong: #c0392b;
  --color-wrong-bg: #fbeae7;
  --color-badge-bg: #e4edf7;
  --color-badge-text: #145da0;
  --shadow-card: 0 2px 10px rgba(20, 40, 70, 0.08);
  --radius: 14px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #10151c;
    --color-surface: #1a212b;
    --color-text: #e7ecf2;
    --color-text-muted: #9aa7b6;
    --color-primary: #4fa3e3;
    --color-primary-dark: #7cc0f2;
    --color-primary-contrast: #0b1620;
    --color-secondary: #232c38;
    --color-border: #2c3644;
    --color-correct: #3fcf8e;
    --color-correct-bg: #123526;
    --color-wrong: #ff6b5e;
    --color-wrong-bg: #3a1c1a;
    --color-badge-bg: #1c2b3d;
    --color-badge-text: #7cc0f2;
    --shadow-card: 0 2px 10px rgba(0, 0, 0, 0.35);
  }
}

* { box-sizing: border-box; }

[hidden] { display: none !important; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", system-ui, -apple-system, sans-serif;
  line-height: 1.7;
  -webkit-text-size-adjust: 100%;
}

body { overflow-x: hidden; }

.sp-only { display: inline; }
@media (min-width: 640px) {
  .sp-only { display: none; }
}

.site-header {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: #fff;
  padding: 28px 16px 22px;
  text-align: center;
}
.site-header h1 {
  margin: 0 0 6px;
  font-size: 1.4rem;
  font-weight: 700;
}
.site-sub {
  margin: 0;
  font-size: 0.85rem;
  opacity: 0.9;
}

.user-bar {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  margin-top: 14px;
  font-size: 0.85rem;
}
.user-bar[hidden] {
  display: none;
}
.btn-text-light {
  color: #fff;
  opacity: 0.85;
  text-decoration: underline;
  padding: 4px 8px;
}

.auth-tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 20px;
}
.auth-tab {
  flex: 1;
  padding: 10px;
  border: none;
  border-radius: 10px;
  background: var(--color-secondary);
  color: var(--color-text-muted);
  font-weight: 700;
  cursor: pointer;
}
.auth-tab.active {
  background: var(--color-primary);
  color: var(--color-primary-contrast);
}
.auth-form input[type="text"],
.auth-form input[type="password"] {
  width: 100%;
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--color-border);
  background: var(--color-secondary);
  color: var(--color-text);
  font-size: 1rem;
}
.auth-error {
  color: var(--color-wrong);
  font-size: 0.88rem;
  background: var(--color-wrong-bg);
  padding: 10px 12px;
  border-radius: 8px;
  margin: 0 0 16px;
}

.category-stat-overall {
  font-weight: 700;
  border-bottom: 1px solid var(--color-border) !important;
  padding-bottom: 10px !important;
  margin-bottom: 4px;
}

main#app {
  max-width: 640px;
  margin: 0 auto;
  padding: 16px 12px 40px;
}

.card {
  background: var(--color-surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  padding: 20px 18px;
  margin-bottom: 16px;
}

.card h2 {
  margin-top: 0;
  font-size: 1.05rem;
}

.notice {
  background: var(--color-badge-bg);
  border-left: 4px solid var(--color-primary);
  border-radius: 8px;
  padding: 14px 16px;
  margin-bottom: 16px;
  font-size: 0.88rem;
  color: var(--color-text);
}
.notice p { margin: 6px 0 0; }

.field { margin-bottom: 18px; }
.field:last-of-type { margin-bottom: 20px; }
.field-label {
  display: block;
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 8px;
}

select#category-select {
  width: 100%;
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--color-border);
  background: var(--color-secondary);
  color: var(--color-text);
  font-size: 1rem;
}

.radio-group {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}
.radio-group label {
  flex: 1 1 auto;
  text-align: center;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--color-border);
  background: var(--color-secondary);
  cursor: pointer;
  font-size: 0.9rem;
  user-select: none;
}
.radio-group input { display: none; }
.radio-group input:checked + span {
  color: var(--color-primary-contrast);
}
.radio-group label:has(input:checked) {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-contrast);
  font-weight: 700;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.92rem;
  cursor: pointer;
}
.checkbox-label input { width: 18px; height: 18px; }

.btn {
  display: inline-block;
  border: none;
  border-radius: 10px;
  padding: 12px 20px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.05s ease, opacity 0.15s ease;
  text-align: center;
}
.btn:active { transform: scale(0.98); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }

.btn-lg { width: 100%; padding: 15px 20px; font-size: 1.05rem; }

.btn-primary {
  background: var(--color-primary);
  color: var(--color-primary-contrast);
}
.btn-secondary {
  background: var(--color-secondary);
  color: var(--color-primary);
  border: 1px solid var(--color-border);
}
.btn-text {
  background: transparent;
  color: var(--color-text-muted);
  font-weight: 500;
  padding: 12px 8px;
}

.stat-card #history-list { font-size: 0.9rem; color: var(--color-text-muted); }
.history-row {
  display: flex;
  justify-content: space-between;
  padding: 6px 0;
  border-bottom: 1px dashed var(--color-border);
}
.history-row:last-child { border-bottom: none; }

/* ===== 試験画面 ===== */
.exam-progress { margin-bottom: 12px; }
.progress-bar {
  height: 8px;
  border-radius: 999px;
  background: var(--color-secondary);
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--color-primary);
  transition: width 0.25s ease;
}
.progress-text {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 6px;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.badge {
  background: var(--color-badge-bg);
  color: var(--color-badge-text);
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 700;
}

.question-card h2 {
  font-size: 1.08rem;
  line-height: 1.6;
  margin-bottom: 18px;
}

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

.choice-btn {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  text-align: left;
  padding: 13px 14px;
  border-radius: 12px;
  border: 1.5px solid var(--color-border);
  background: var(--color-secondary);
  color: var(--color-text);
  font-size: 0.96rem;
  cursor: pointer;
  width: 100%;
}
.choice-btn .choice-index {
  flex: none;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--color-text-muted);
}
.choice-btn:disabled { cursor: default; }

.choice-btn.selected {
  border-color: var(--color-primary);
  background: var(--color-badge-bg);
}
.choice-btn.selected .choice-index {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

.exam-timer {
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--color-primary);
}
.exam-timer.is-warning { color: var(--color-wrong); }

.exam-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: 10px;
}
.nav-cell {
  width: 30px;
  height: 30px;
  padding: 0;
  border-radius: 7px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-muted);
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
}
.nav-cell.done {
  background: var(--color-badge-bg);
  color: var(--color-badge-text);
  border-color: var(--color-badge-text);
}
.nav-cell.ok {
  background: var(--color-correct-bg);
  color: var(--color-correct);
  border-color: var(--color-correct);
}
.nav-cell.ng {
  background: var(--color-wrong-bg);
  color: var(--color-wrong);
  border-color: var(--color-wrong);
}
.nav-cell.current {
  outline: 2px solid var(--color-primary);
  outline-offset: 1px;
}
.choice-btn.correct {
  border-color: var(--color-correct);
  background: var(--color-correct-bg);
}
.choice-btn.correct .choice-index {
  background: var(--color-correct);
  border-color: var(--color-correct);
  color: #fff;
}
.choice-btn.wrong {
  border-color: var(--color-wrong);
  background: var(--color-wrong-bg);
}
.choice-btn.wrong .choice-index {
  background: var(--color-wrong);
  border-color: var(--color-wrong);
  color: #fff;
}
.choice-btn.dim { opacity: 0.55; }

.feedback { margin-top: 18px; padding-top: 16px; border-top: 1px dashed var(--color-border); }
.feedback-result {
  font-weight: 700;
  margin-bottom: 8px;
  font-size: 1rem;
}
.feedback-result.is-correct { color: var(--color-correct); }
.feedback-result.is-wrong { color: var(--color-wrong); }
.feedback-explanation {
  margin: 0;
  font-size: 0.92rem;
  color: var(--color-text-muted);
  background: var(--color-secondary);
  padding: 12px 14px;
  border-radius: 10px;
}

.exam-actions {
  position: sticky;
  bottom: 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  margin: 12px -12px 0;
  padding: 10px 12px calc(10px + env(safe-area-inset-bottom));
  background: linear-gradient(to top, var(--color-bg) 70%, transparent);
}
.exam-actions .btn-primary { flex: 1; }
.exam-actions .btn { box-shadow: 0 -2px 10px rgba(20, 40, 70, 0.06); }

#screen-exam.screen:not([hidden]) {
  min-height: calc(100vh - 120px);
  display: flex;
  flex-direction: column;
}
#screen-exam .question-card { flex: 1; }

/* ===== 結果画面 ===== */
.result-summary { text-align: center; }
.score-circle {
  width: 130px;
  height: 130px;
  border-radius: 50%;
  border: 8px solid var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 12px auto;
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--color-primary);
}
#score-detail { color: var(--color-text-muted); font-size: 0.95rem; }
.pass-judge {
  margin: 6px 0 0;
  font-weight: 700;
  font-size: 1rem;
}
.pass-judge.is-pass { color: var(--color-correct); }
.pass-judge.is-fail { color: var(--color-wrong); }

.wrong-item {
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 14px 16px;
  margin-bottom: 12px;
}
.wrong-item .wrong-category {
  font-size: 0.75rem;
  color: var(--color-badge-text);
  font-weight: 700;
  margin-bottom: 4px;
  display: inline-block;
}
.wrong-item .wrong-question {
  font-weight: 700;
  margin: 4px 0 10px;
}
.wrong-item .wrong-your-answer { color: var(--color-wrong); font-size: 0.9rem; margin: 4px 0; }
.wrong-item .wrong-correct-answer { color: var(--color-correct); font-size: 0.9rem; margin: 4px 0; }
.wrong-item .wrong-explanation {
  margin-top: 8px;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  background: var(--color-secondary);
  padding: 10px 12px;
  border-radius: 8px;
}

#all-correct-msg {
  text-align: center;
  color: var(--color-correct);
  font-weight: 700;
}

.site-footer {
  text-align: center;
  font-size: 0.78rem;
  color: var(--color-text-muted);
  padding: 20px 16px 32px;
}

.screen[hidden] { display: none; }