/* ============================================================
   page-low-noise-sirocco-fan.css
   저소음 시로코팬 교체 — 구조 설계 관점 안내 페이지 전용 스타일
   Title: Noto Sans KR 500, 대형 편집형 타이포 / Body: Noto Sans KR 400
   배경: 순백(#fff) — 세트 내 유일하게 틴트 없는 페이지
   Layout signature: 소음 발생 경로 4구간 다이어그램 + 얇은 헤어라인 구분선
   ============================================================ */

:root {
  --cta-primary: #334155;
  --cta-secondary: #FFFFFF;
  --lns-ink: #334155;
  --lns-sub: #94A3B8;
  --lns-line: #E2E8F0;
}

body { font-family: 'Noto Sans KR', -apple-system, sans-serif; font-weight: 400; background: #FFFFFF; color: var(--lns-ink); }
h1, h2, h3 { font-family: 'Noto Sans KR', sans-serif; font-weight: 500; color: var(--lns-ink); }

/* ---- hairline divider (this page's signature — thin rule, no color block) ---- */
.lns-divider { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.lns-divider::before { content: ""; display: block; height: 1px; background: var(--lns-line); margin: 48px 0; }

/* ---- intro: large editorial typography ---- */
.lns-intro { max-width: 760px; margin: 0 auto; padding: 64px 20px 8px; text-align: center; }
.lns-eyebrow { color: var(--lns-sub); font-weight: 500; font-size: .85rem; letter-spacing: .14em; margin-bottom: 18px; text-transform: none; }
.lns-intro h1 {
  font-size: clamp(2rem, 5.4vw, 3.1rem);
  letter-spacing: .08em;
  line-height: 1.35;
  margin-bottom: 26px;
}
.lns-intro p { color: var(--lns-ink); line-height: 1.9; font-size: 1rem; }

/* ---- section shell ---- */
.lns-section { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.lns-section h2 {
  font-size: clamp(1.3rem, 3vw, 1.7rem);
  letter-spacing: .04em;
  margin-bottom: 24px;
  line-height: 1.5;
}
.lns-section h2 + h2 { margin-top: 48px; }
.lns-section p { margin-bottom: 16px; line-height: 1.9; color: var(--lns-ink); }
.lns-note { font-size: .85rem; color: var(--lns-sub); margin-top: 6px; }

/* ---- noise-path diagram (signature) ---- */
.lns-diagram { margin: 32px 0 18px; }
.lns-diagram svg { width: 100%; height: auto; display: block; }
.lns-box { fill: #FFFFFF; stroke: var(--lns-ink); stroke-width: 1.5; }
.lns-box-title { font-size: 20px; font-weight: 500; fill: var(--lns-ink); }
.lns-box-sub { font-size: 14px; fill: var(--lns-sub); }
.lns-arrow { fill: none; stroke: var(--lns-sub); stroke-width: 1.5; }
.lns-diagram-summary { color: var(--lns-ink); line-height: 1.9; padding: 18px 22px; border-left: 2px solid var(--lns-ink); margin-bottom: 8px; }

/* ---- numbered stage explanations ---- */
.lns-stage { margin-top: 8px; }
.lns-stage h3 { font-size: 1.1rem; margin: 30px 0 10px; display: flex; align-items: center; gap: 12px; }
.lns-stage h3:first-child { margin-top: 0; }
.lns-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 28px; height: 28px; border-radius: 50%; border: 1.5px solid var(--lns-ink);
  color: var(--lns-ink); font-size: .85rem; font-weight: 500; flex-shrink: 0;
}

.lns-sub-h { font-size: 1.3rem; letter-spacing: .04em; margin-bottom: 22px; }

/* ---- before/after two-column structural comparison ---- */
.lns-compare { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin: 24px 0 8px; }
.lns-compare-col { border: 1px solid var(--lns-line); border-radius: 2px; padding: 24px 22px; }
.lns-compare-col--accent { border-color: var(--lns-ink); }
.lns-compare-col h3 { font-size: 1.05rem; margin-bottom: 16px; }
.lns-compare-col ul { list-style: none; }
.lns-compare-col li { padding: 9px 0; border-top: 1px solid var(--lns-line); font-size: .92rem; line-height: 1.6; color: var(--lns-ink); }
.lns-compare-col li:first-child { border-top: none; }

@media (max-width: 700px) {
  .lns-compare { grid-template-columns: 1fr; }
}

/* ---- glossary (dl) ---- */
.lns-glossary { border-top: 1px solid var(--lns-line); }
.lns-glossary dt { padding-top: 18px; font-weight: 500; color: var(--lns-ink); font-size: 1rem; }
.lns-glossary dd { margin: 4px 0 14px; color: var(--lns-sub); font-size: .92rem; line-height: 1.7; }

/* ---- misconception accordion (details/summary) ---- */
.lns-faq { display: flex; flex-direction: column; }
.lns-faq details { border-top: 1px solid var(--lns-line); padding: 4px 0; }
.lns-faq details:last-child { border-bottom: 1px solid var(--lns-line); }
.lns-faq summary { padding: 16px 28px 16px 0; font-weight: 500; color: var(--lns-ink); font-size: 1rem; position: relative; }
.lns-faq summary::after {
  content: "+"; position: absolute; right: 4px; top: 14px; font-size: 1.3rem; color: var(--lns-sub); font-weight: 400;
}
.lns-faq details[open] summary::after { content: "\2212"; }
.lns-faq .lns-faq-a { padding: 0 0 18px; color: var(--lns-ink); line-height: 1.85; }

/* ---- exactly one animation type on this page: CSS-only scroll reveal ---- */
.lns-section, .lns-intro, .lns-diagram, .lns-compare-col, .lns-faq details {
  animation: lns-reveal .5s ease-out both;
  animation-timeline: view();
  animation-range: entry 0% cover 25%;
}
@keyframes lns-reveal {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: none; }
}
@media (prefers-reduced-motion: reduce) {
  .lns-section, .lns-intro, .lns-diagram, .lns-compare-col, .lns-faq details { animation: none; }
}

@media (max-width: 480px) {
  .lns-intro { padding: 48px 16px 4px; }
  .lns-box-title { font-size: 17px; }
  .lns-box-sub { font-size: 12px; }
}

/* ---- site photo: 4:3 crop (요청 반영) ---- */
.photo-row img { aspect-ratio: 4 / 3; }