:root {
  --bg: #0b0f1a;
  --bg-soft: #111827;
  --surface: #161e2e;
  --surface-2: #1d2638;
  --border: #2a3346;
  --text: #e7ecf3;
  --text-soft: #a8b2c4;
  --muted: #6b778c;
  --accent: #6ee7b7;
  --accent-2: #60a5fa;
  --accent-3: #f0abfc;
  --warn: #fbbf24;
  --danger: #f87171;
  --good: #34d399;
  --shadow: 0 10px 30px rgba(0,0,0,.35);
  --radius: 14px;
  --max: 1200px;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f7f8fc;
    --bg-soft: #ffffff;
    --surface: #ffffff;
    --surface-2: #f1f3f9;
    --border: #e3e7ef;
    --text: #0f172a;
    --text-soft: #475569;
    --muted: #94a3b8;
    --shadow: 0 6px 20px rgba(15,23,42,.08);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "Microsoft JhengHei", "Noto Sans TC", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: var(--max); margin: 0 auto; padding: 0 24px; }

/* Hero */
.hero {
  position: relative;
  background:
    radial-gradient(1200px 500px at 80% -10%, rgba(110,231,183,.18), transparent 60%),
    radial-gradient(900px 500px at -10% 20%, rgba(96,165,250,.18), transparent 60%),
    linear-gradient(180deg, var(--bg-soft), var(--bg));
  border-bottom: 1px solid var(--border);
  padding: 28px 0 56px;
}
.hero-top {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 28px;
}
.logo { font-weight: 800; font-size: 20px; letter-spacing: .5px; }
.hero-meta { display: flex; gap: 12px; align-items: center; color: var(--text-soft); font-size: 14px; }
.badge {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0b0f1a; font-weight: 700; padding: 4px 10px; border-radius: 999px; font-size: 12px;
}
.hero h1 {
  font-size: clamp(28px, 4.5vw, 48px);
  margin: 0 0 8px;
  background: linear-gradient(135deg, #fff, var(--accent));
  -webkit-background-clip: text; background-clip: text; color: transparent;
  letter-spacing: -.5px;
}
.lead { color: var(--text-soft); font-size: 18px; max-width: 720px; margin: 0 0 24px; }

.hero-search input {
  width: 100%; max-width: 560px;
  padding: 14px 18px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font-size: 16px;
  outline: none;
  transition: border .2s, box-shadow .2s;
}
.hero-search input:focus { border-color: var(--accent-2); box-shadow: 0 0 0 4px rgba(96,165,250,.18); }

/* Hero jump nav */
.hero-jump {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
}
.hero-jump a {
  display: inline-flex;
  align-items: center;
  padding: 7px 14px;
  border-radius: 99px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-soft);
  font-size: 13px;
  font-weight: 600;
  text-decoration: none;
  transition: all .15s ease;
}
.hero-jump a:hover {
  color: var(--text);
  border-color: var(--accent-2);
  transform: translateY(-1px);
}

/* Category Nav */
.catnav {
  position: sticky; top: 0; z-index: 30;
  background: rgba(11,15,26,.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
@media (prefers-color-scheme: light) {
  .catnav { background: rgba(255,255,255,.85); }
}
.cat-tabs {
  display: flex; gap: 8px; overflow-x: auto;
  padding: 12px 0;
  scrollbar-width: thin;
}
.cat-tabs::-webkit-scrollbar { height: 6px; }
.cat-tabs::-webkit-scrollbar-thumb { background: var(--border); border-radius: 99px; }

.cat-btn {
  flex-shrink: 0;
  padding: 8px 16px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-soft);
  font-size: 14px; font-weight: 600;
  cursor: pointer;
  transition: all .15s ease;
  white-space: nowrap;
}
.cat-btn:hover { border-color: var(--accent-2); color: var(--text); }
.cat-btn.active {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0b0f1a; border-color: transparent;
}
.cat-btn .icon { margin-right: 6px; }

/* Sections */
main { padding: 40px 0 80px; }
section { margin-bottom: 48px; }
section h2 { font-size: 22px; margin: 0 0 6px; letter-spacing: -.2px; }
.section-desc { color: var(--text-soft); margin: 0 0 20px; font-size: 15px; }
.muted { color: var(--muted); font-weight: 500; font-size: 16px; }

.cat-header { margin-bottom: 18px; }

/* Card grid */
.card-grid {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  display: flex; flex-direction: column;
  cursor: pointer;
  transition: transform .15s ease, box-shadow .2s ease, border-color .2s;
  position: relative;
  overflow: hidden;
}
.card::before {
  content: "";
  position: absolute; top: 0; left: 0; right: 0; height: 4px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2), var(--accent-3));
  opacity: .8;
}
.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  border-color: var(--accent-2);
}

.card-bank { font-size: 12px; color: var(--muted); letter-spacing: .5px; text-transform: uppercase; }
.card-name { font-size: 18px; font-weight: 700; margin: 4px 0 10px; }
.card-tagline {
  background: var(--surface-2);
  border-radius: 8px;
  padding: 10px 12px;
  margin-bottom: 12px;
  font-size: 14px;
  color: var(--text-soft);
  border-left: 3px solid var(--accent);
}
.card-rate {
  font-size: 24px; font-weight: 800;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text; background-clip: text; color: transparent;
  margin-bottom: 8px;
}
.card-rate .unit { font-size: 14px; color: var(--text-soft); -webkit-text-fill-color: var(--text-soft); }

.tag-row { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0 12px; }
.tag {
  font-size: 11px; padding: 3px 8px; border-radius: 99px;
  background: var(--surface-2); color: var(--text-soft);
  border: 1px solid var(--border);
}
.tag.good { color: var(--good); border-color: rgba(52,211,153,.4); }
.tag.warn { color: var(--warn); border-color: rgba(251,191,36,.4); }

.card-meta {
  display: flex; justify-content: space-between;
  font-size: 12px; color: var(--muted);
  border-top: 1px dashed var(--border);
  padding-top: 10px; margin-top: auto;
}
.card-meta .expire { color: var(--warn); font-weight: 600; }

/* Quick Pick — accordion */
.qp-list { display: flex; flex-direction: column; gap: 10px; }
.qp-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color .2s, box-shadow .2s;
}
.qp-item[open] {
  border-color: var(--accent-2);
  box-shadow: var(--shadow);
}
.qp-item summary {
  list-style: none;
  cursor: pointer;
  padding: 14px 18px;
  display: flex;
  align-items: center;
  gap: 14px;
  user-select: none;
}
.qp-item summary::-webkit-details-marker { display: none; }
.qp-item summary:hover { background: var(--surface-2); }
.qp-icon { font-size: 22px; flex-shrink: 0; line-height: 1; }
.qp-scene-block { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 2px; }
.qp-scene { font-weight: 700; font-size: 15px; }
.qp-desc { color: var(--muted); font-size: 12px; }
.qp-first-pill {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0b0f1a;
  font-size: 12px;
  font-weight: 700;
  padding: 6px 12px;
  border-radius: 99px;
  white-space: nowrap;
  flex-shrink: 0;
}
.qp-arrow {
  color: var(--muted);
  font-size: 18px;
  transition: transform .25s ease;
  flex-shrink: 0;
}
.qp-item[open] .qp-arrow { transform: rotate(180deg); color: var(--accent-2); }

.qp-detail-body { border-top: 1px solid var(--border); background: var(--surface-2); padding: 4px 0; }
.qp-top5 {
  list-style: none;
  padding: 0;
  margin: 0;
}
.qp-card-item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 12px 18px;
  border-bottom: 1px dashed var(--border);
}
.qp-card-item:last-child { border-bottom: none; }
.qp-rank {
  background: var(--surface);
  color: var(--accent);
  font-weight: 800;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  border: 1px solid var(--border);
}
.qp-rank-1 { background: linear-gradient(135deg, #facc15, #f59e0b); color: #1f1f1f; border-color: transparent; }
.qp-rank-2 { background: linear-gradient(135deg, #e2e8f0, #94a3b8); color: #1f1f1f; border-color: transparent; }
.qp-rank-3 { background: linear-gradient(135deg, #fb923c, #c2410c); color: #fff; border-color: transparent; }
.qp-info { flex: 1; min-width: 0; }
.qp-card-name { font-weight: 600; line-height: 1.4; color: var(--text); }
.qp-card-name .qp-rate {
  color: var(--accent);
  font-weight: 800;
  margin-left: 4px;
}
.qp-note { color: var(--text-soft); font-size: 13px; margin-top: 2px; }

/* Card tier inline */
.card-tier {
  display: inline-block;
  margin-left: 8px;
  font-size: 10px;
  padding: 2px 6px;
  background: var(--surface-2);
  color: var(--text-soft);
  border-radius: 4px;
  text-transform: none;
  letter-spacing: 0;
}

/* Modal meta pills + detail grid */
.meta-pills { display: flex; gap: 6px; flex-wrap: wrap; margin: 8px 0 0; }
.meta-pill {
  font-size: 11px;
  padding: 3px 9px;
  border-radius: 99px;
  background: var(--surface-2);
  color: var(--text-soft);
  border: 1px solid var(--border);
}
.detail-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
  margin-top: 18px;
}
.detail-grid .detail-section { margin-top: 0; padding: 12px 14px; background: var(--surface-2); border-radius: 10px; }
.detail-grid .detail-section h4 { margin-bottom: 4px; }
.detail-grid .detail-section p { margin: 0; color: var(--text); font-size: 14px; }

/* How-to */
.howto-list { padding-left: 20px; color: var(--text-soft); }
.howto-list li { margin-bottom: 10px; }
.howto-list strong { color: var(--text); }

/* Sources */
.source-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }
.source-list li {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 14px;
  font-size: 14px;
}
.source-list a { color: var(--accent-2); text-decoration: none; }
.source-list a:hover { text-decoration: underline; }
.source-list .src-cat { color: var(--muted); font-size: 12px; display: block; margin-top: 2px; }

/* Modal */
.modal { position: fixed; inset: 0; z-index: 100; display: flex; align-items: center; justify-content: center; }
.modal[hidden] { display: none; }
.modal-backdrop { position: absolute; inset: 0; background: rgba(0,0,0,.65); backdrop-filter: blur(4px); }
.modal-body {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  max-width: 720px; width: calc(100% - 32px);
  max-height: 85vh; overflow-y: auto;
  padding: 28px 28px 24px;
  box-shadow: var(--shadow);
}
.modal-close {
  position: absolute; top: 12px; right: 12px;
  background: var(--surface-2); border: 1px solid var(--border);
  width: 36px; height: 36px; border-radius: 50%;
  font-size: 22px; color: var(--text); cursor: pointer;
  line-height: 1;
}
.modal-close:hover { background: var(--surface); border-color: var(--accent-2); }
.modal h3 { margin: 0 0 6px; font-size: 24px; }
.modal .modal-bank { color: var(--muted); font-size: 13px; }
.modal .detail-section { margin-top: 18px; }
.modal .detail-section h4 {
  font-size: 13px; color: var(--text-soft); margin: 0 0 8px;
  text-transform: uppercase; letter-spacing: 1px;
}
.modal ul { padding-left: 20px; margin: 0; }
.modal ul li { margin-bottom: 4px; color: var(--text-soft); }
.modal .pros li { color: var(--good); }
.modal .cons li { color: var(--danger); }
.modal .source-link {
  display: inline-block; margin-top: 6px;
  font-size: 13px; color: var(--accent-2); text-decoration: none;
}
.modal .source-link:hover { text-decoration: underline; }

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
  color: var(--text-soft);
  font-size: 14px;
  text-align: center;
}
footer .disclaimer { color: var(--muted); font-size: 12px; margin-top: 4px; }

/* ============================================
   🧮 回饋計算機
   ============================================ */
.calc-section { scroll-margin-top: 80px; }
.small { font-size: 12px; margin-top: 8px; }
.cat-current { color: var(--text-soft); font-size: 14px; margin: 4px 0 18px; }
.cat-current strong { color: var(--accent); margin-left: 4px; }

.calc-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 20px;
  align-items: start;
}
.calc-inputs {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 8px 0;
}
.calc-row {
  display: grid;
  grid-template-columns: 1fr 160px 1.4fr;
  gap: 14px;
  align-items: center;
  padding: 12px 18px;
  border-bottom: 1px solid var(--border);
}
.calc-row:last-child { border-bottom: none; }
.calc-row-label {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 14px;
}
.calc-row-icon { font-size: 18px; }
.calc-row-input-wrap {
  position: relative;
  display: flex;
  align-items: center;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0 10px;
}
.calc-row-input-wrap:focus-within { border-color: var(--accent-2); box-shadow: 0 0 0 3px rgba(96,165,250,.15); }
.calc-currency { color: var(--muted); font-size: 13px; padding-right: 6px; }
.calc-input {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text);
  font-size: 15px;
  padding: 8px 0;
  outline: none;
  width: 100%;
  font-family: inherit;
}
.calc-input::-webkit-outer-spin-button,
.calc-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.calc-row-best { font-size: 12px; color: var(--text-soft); line-height: 1.4; }
.calc-row-card { color: var(--text); font-weight: 600; }
.calc-row-rate { color: var(--accent); font-weight: 700; }
.calc-row-rate .muted { color: var(--muted); font-weight: 400; }

.calc-result {
  position: sticky;
  top: 70px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.calc-result-header {
  background: linear-gradient(135deg, rgba(110,231,183,.12), rgba(96,165,250,.12));
  padding: 18px 20px;
  border-bottom: 1px solid var(--border);
}
.calc-label { color: var(--text-soft); font-size: 12px; letter-spacing: 1px; text-transform: uppercase; }
.calc-total {
  font-size: 32px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  margin: 4px 0;
  line-height: 1.1;
}
.calc-yearly { font-size: 13px; color: var(--text-soft); }
.calc-yearly strong { color: var(--accent-3); }
.calc-summary { padding: 14px 18px; max-height: 260px; overflow-y: auto; border-bottom: 1px solid var(--border); }
.calc-breakdown { list-style: none; padding: 0; margin: 0; font-size: 12px; }
.calc-breakdown li {
  display: grid;
  grid-template-columns: 1.3fr 0.9fr 0.6fr 0.9fr;
  gap: 4px;
  padding: 6px 0;
  border-bottom: 1px dashed var(--border);
  align-items: center;
}
.calc-breakdown li:last-child { border-bottom: none; }
.calc-bd-cat { color: var(--text); font-weight: 500; }
.calc-bd-amt, .calc-bd-rate { color: var(--text-soft); text-align: right; }
.calc-bd-cb { color: var(--accent); font-weight: 700; text-align: right; }

.calc-cards-needed { padding: 14px 18px; }
.calc-cards-needed h4 { margin: 0 0 8px; font-size: 13px; color: var(--text-soft); text-transform: uppercase; letter-spacing: 1px; }
.calc-cards-needed h4 span { color: var(--accent); font-size: 16px; }
.calc-cards-needed ul { list-style: none; padding: 0; margin: 0; font-size: 13px; }
.calc-cards-needed li { padding: 4px 0; color: var(--text); }

/* ============================================
   👥 信用卡組合推薦
   ============================================ */
.combos-section { scroll-margin-top: 80px; }
.combos-grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
}
.combo-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  flex-direction: column;
  transition: border-color .2s, transform .15s;
}
.combo-card:hover {
  border-color: var(--accent-2);
  transform: translateY(-2px);
}
.combo-head {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 12px;
}
.combo-icon {
  font-size: 32px;
  width: 50px;
  height: 50px;
  background: var(--surface-2);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.combo-name { font-weight: 800; font-size: 17px; line-height: 1.2; }
.combo-persona { font-size: 12px; color: var(--text-soft); margin-top: 2px; }
.combo-desc { color: var(--text-soft); font-size: 14px; margin: 0 0 14px; }
.combo-est {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 14px;
  background: linear-gradient(135deg, rgba(110,231,183,.08), rgba(96,165,250,.08));
  border-radius: 10px;
  margin-bottom: 14px;
}
.combo-est-label { font-size: 12px; color: var(--text-soft); }
.combo-est-val { font-weight: 800; color: var(--accent); }
.combo-cards { list-style: none; padding: 0; margin: 0; }
.combo-card-item {
  padding: 10px 0;
  border-top: 1px dashed var(--border);
  display: grid;
  grid-template-columns: 70px 1fr;
  gap: 10px;
  align-items: baseline;
}
.combo-card-item:first-child { border-top: none; padding-top: 0; }
.combo-card-role {
  font-size: 11px;
  font-weight: 700;
  color: var(--accent-2);
  background: var(--surface-2);
  padding: 3px 8px;
  border-radius: 6px;
  text-align: center;
  align-self: start;
}
.combo-card-name { font-weight: 600; color: var(--text); font-size: 14px; }
.combo-card-reason { grid-column: 2; font-size: 12px; color: var(--text-soft); margin-top: 2px; }

/* ============================================
   📅 全年優惠日曆
   ============================================ */
.calendar-section { scroll-margin-top: 80px; }
.calendar-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.cal-item {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 18px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
  align-items: center;
  transition: border-color .2s;
}
.cal-item:hover { border-color: var(--accent-2); }
.cal-period {
  font-size: 13px;
  font-weight: 700;
  color: var(--accent-2);
  background: var(--surface-2);
  padding: 6px 10px;
  border-radius: 8px;
  text-align: center;
}
.cal-title { font-weight: 700; font-size: 15px; margin-bottom: 2px; }
.cal-desc { font-size: 13px; color: var(--text-soft); line-height: 1.5; }

/* ============================================
   ⚠️ 避雷區
   ============================================ */
.pitfalls-section { scroll-margin-top: 80px; }
.pitfalls-grid {
  display: grid;
  gap: 14px;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
}
.pitfall-card {
  display: grid;
  grid-template-columns: 50px 1fr;
  gap: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--warn);
  border-radius: 10px;
  padding: 16px 18px;
}
.pitfall-num {
  font-size: 24px;
  font-weight: 800;
  color: var(--warn);
  line-height: 1;
}
.pitfall-body h4 {
  margin: 0 0 6px;
  font-size: 15px;
  color: var(--text);
}
.pitfall-body p {
  margin: 0;
  font-size: 13px;
  color: var(--text-soft);
  line-height: 1.55;
}

/* ============================================
   📖 名詞解釋
   ============================================ */
.glossary-section { scroll-margin-top: 80px; }
.glossary-list {
  display: grid;
  gap: 8px;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
}
.glossary-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  transition: border-color .2s;
}
.glossary-item[open] { border-color: var(--accent-2); }
.glossary-item summary {
  list-style: none;
  cursor: pointer;
  padding: 12px 16px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 700;
  font-size: 14px;
  user-select: none;
}
.glossary-item summary::-webkit-details-marker { display: none; }
.glossary-item summary:hover { background: var(--surface-2); }
.gloss-arrow { color: var(--muted); font-size: 14px; transition: transform .2s; }
.glossary-item[open] .gloss-arrow { transform: rotate(180deg); color: var(--accent-2); }
.gloss-desc {
  padding: 0 16px 14px;
  font-size: 13px;
  color: var(--text-soft);
  line-height: 1.6;
  border-top: 1px solid var(--border);
  padding-top: 12px;
}

/* ============================================
   How-to list link styling
   ============================================ */
.howto-list a { color: var(--accent-2); text-decoration: none; }
.howto-list a:hover { text-decoration: underline; }

/* ============================================
   Collapsible Section (整個區塊可收合)
   ============================================ */
.collapsible-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color .2s;
}
.collapsible-section:hover { border-color: var(--accent-2); }
.collapsible-section[open] { border-color: var(--accent-2); }
.collapsible-section > summary {
  list-style: none;
  cursor: pointer;
  padding: 18px 22px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
  gap: 16px;
}
.collapsible-section > summary::-webkit-details-marker { display: none; }
.collapsible-section > summary:hover { background: var(--surface-2); }
.collapsible-section > summary h2 {
  margin: 0;
  font-size: 22px;
  letter-spacing: -.2px;
  flex: 1;
}
.collapsible-section > summary h2 .muted {
  font-size: 14px;
  font-weight: 500;
  margin-left: 6px;
}
.section-arrow {
  color: var(--muted);
  font-size: 22px;
  transition: transform .25s ease;
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  background: var(--surface-2);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}
.collapsible-section[open] .section-arrow {
  transform: rotate(180deg);
  color: var(--accent-2);
  background: rgba(96,165,250,.15);
}
.collapse-body {
  padding: 4px 22px 22px;
  border-top: 1px solid var(--border);
  padding-top: 18px;
}
.collapse-body .section-desc { margin-top: 0; }

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 900px) {
  .calc-wrap { grid-template-columns: 1fr; }
  .calc-result { position: static; }
  .calc-row { grid-template-columns: 1fr 140px; }
  .calc-row-best { grid-column: 1 / -1; }
  .cal-item { grid-template-columns: 1fr; gap: 10px; }
  .cal-period { justify-self: start; }
}
@media (max-width: 640px) {
  .hero { padding: 20px 0 36px; }
  .hero-top { flex-direction: column; align-items: flex-start; gap: 8px; }
  section h2 { font-size: 20px; }
  .card-grid { grid-template-columns: 1fr; }
  .qp-item summary { flex-wrap: wrap; }
  .qp-first-pill { font-size: 11px; padding: 4px 10px; }
  .qp-scene-block { flex-basis: calc(100% - 50px); }
  .qp-first-pill { flex-basis: 100%; text-align: center; margin-left: 36px; }
  .calc-row { grid-template-columns: 1fr; gap: 8px; padding: 12px 14px; }
  .combo-card-item { grid-template-columns: 1fr; }
  .combo-card-role { justify-self: start; }
  .combo-card-reason { grid-column: 1; }
}