:root {
  --navy: #0B3556;
  --navy-deep: #08283F;
  --cyan: #7FDBFF;
  --text: #EAF6FF;
  --text-dim: #B9D4E6;
  --radius: 2px;
  --max: 920px;
}

* { box-sizing: border-box; }

html { font-display: swap; }

body {
  margin: 0;
  background: var(--navy);
  color: var(--text);
  font-family: 'Noto Sans KR', sans-serif;
  font-weight: 400;
  line-height: 1.75;
  font-size: 16px;
  overflow-x: hidden;
}

h1, h2, h3 {
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  color: var(--cyan);
  line-height: 1.4;
}

.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
}

a { color: var(--cyan); }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.section-inner {
  max-width: var(--max);
  margin-inline: auto;
  padding: 48px 20px;
}

/* Header */
.site-header {
  border-bottom: 1px solid rgba(127, 219, 255, 0.35);
  position: sticky;
  top: 0;
  background: var(--navy-deep);
  z-index: 20;
}

.header-inner {
  max-width: var(--max);
  margin-inline: auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  position: relative;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.wordmark {
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  color: var(--cyan);
  font-size: 1rem;
  letter-spacing: 0.06em;
}

.hamburger {
  background: none;
  border: none;
  display: none;
  cursor: pointer;
  padding: 6px;
}

.main-nav ul {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  margin: 0;
  padding: 0;
}

.main-nav a {
  text-decoration: none;
  color: var(--text-dim);
  font-weight: 500;
  font-size: 0.92rem;
}

.main-nav a:hover { color: var(--cyan); }

@media (max-width: 720px) {
  .hamburger { display: block; }
  .main-nav {
    display: none;
    width: 100%;
    order: 3;
  }
  .main-nav ul {
    flex-direction: column;
    gap: 0;
    padding-top: 10px;
  }
  .main-nav ul li {
    border-top: 1px solid rgba(127, 219, 255, 0.25);
  }
  .main-nav ul li a {
    display: block;
    padding: 12px 4px;
  }
  .main-nav.is-open { display: block; }
}

/* Hero — blueprint graph-paper grid + dimension lines */
.hero {
  position: relative;
  background-color: var(--navy-deep);
  background-image:
    repeating-linear-gradient(0deg, rgba(127, 219, 255, 0.14) 0, rgba(127, 219, 255, 0.14) 1px, transparent 1px, transparent 32px),
    repeating-linear-gradient(90deg, rgba(127, 219, 255, 0.14) 0, rgba(127, 219, 255, 0.14) 1px, transparent 1px, transparent 32px),
    repeating-linear-gradient(0deg, rgba(127, 219, 255, 0.06) 0, rgba(127, 219, 255, 0.06) 1px, transparent 1px, transparent 8px),
    repeating-linear-gradient(90deg, rgba(127, 219, 255, 0.06) 0, rgba(127, 219, 255, 0.06) 1px, transparent 1px, transparent 8px);
  padding: 40px 20px 56px;
}

.hero-grid { display: none; }

.hero-dim {
  max-width: var(--max);
  margin-inline: auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
}

.hero-dim span {
  flex: 1;
  height: 0;
  border-top: 1px dashed rgba(127, 219, 255, 0.6);
  position: relative;
}

.hero-dim span::before,
.hero-dim span::after {
  content: "";
  position: absolute;
  top: -5px;
  width: 1px;
  height: 10px;
  background: rgba(127, 219, 255, 0.6);
}

.hero-dim span::before { left: 0; }
.hero-dim span::after { right: 0; }

.hero-dim--top { margin-bottom: 24px; }
.hero-dim--bottom { margin-top: 24px; }

.hero-panel {
  max-width: 680px;
  margin-inline: auto;
  padding: 0 20px;
  border-left: 2px solid var(--cyan);
  padding-left: 24px;
}

.hero-tag {
  font-family: 'Space Mono', monospace;
  color: var(--cyan);
  letter-spacing: 0.08em;
  font-size: 0.82rem;
  margin: 0 0 14px;
  text-transform: uppercase;
}

.hero h1 {
  font-size: clamp(1.7rem, 4vw, 2.4rem);
  margin: 0 0 18px;
  color: var(--text);
}

.hero-lead {
  margin: 0 0 28px;
  font-size: 1.02rem;
  color: var(--text-dim);
  max-width: 56ch;
}

/* CTA buttons */
.cta {
  display: inline-block;
  text-decoration: none;
  border: 2px solid var(--cyan);
  color: var(--cyan);
  background: transparent;
  border-radius: var(--radius);
  padding: 12px 26px;
  font-weight: 500;
  font-family: 'Space Mono', monospace;
  font-size: 0.92rem;
  letter-spacing: 0.02em;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.cta:hover {
  background: var(--cyan);
  color: var(--navy-deep);
}

.cta-group {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

/* Section numbering */
.content-section { border-top: 1px solid rgba(127, 219, 255, 0.25); }

.section-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius);
  border: 1px solid var(--cyan);
  color: var(--cyan);
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  margin-bottom: 12px;
}

.content-section h2 {
  font-size: 1.3rem;
  margin: 0 0 16px;
}

.content-section p { color: var(--text-dim); }

/* Table */
.spec-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 16px;
  font-size: 0.95rem;
}

.spec-table th, .spec-table td {
  border: 1px solid rgba(127, 219, 255, 0.35);
  padding: 10px 12px;
  text-align: left;
  color: var(--text-dim);
}

.spec-table thead th {
  background: rgba(127, 219, 255, 0.12);
  color: var(--cyan);
  font-family: 'Space Mono', monospace;
}

/* Branch / callout boxes */
.branch-box {
  display: grid;
  gap: 16px;
  margin-top: 20px;
}

.branch-item {
  border: 1px solid rgba(127, 219, 255, 0.3);
  border-left: 3px solid var(--cyan);
  border-radius: var(--radius);
  padding: 16px 20px;
  background: rgba(127, 219, 255, 0.04);
}

.branch-item h3 {
  font-size: 1rem;
  margin: 0 0 8px;
  color: var(--cyan);
}

.branch-item p { margin: 0; color: var(--text-dim); }

/* Formula box */
.formula-box {
  border: 1px dashed var(--cyan);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin-top: 16px;
  background: rgba(127, 219, 255, 0.06);
}

.formula {
  font-family: 'Space Mono', monospace;
  color: var(--cyan);
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.6;
}

/* Checklist */
.checklist {
  list-style: none;
  padding: 0;
  margin: 16px 0 0;
  display: grid;
  gap: 10px;
}

.checklist li {
  padding-left: 30px;
  position: relative;
  color: var(--text-dim);
}

.checklist li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 3px;
  width: 16px;
  height: 16px;
  border: 2px solid var(--cyan);
  border-radius: var(--radius);
}

/* FAQ */
.faq-list {
  margin-top: 16px;
  display: grid;
  gap: 10px;
}

.faq-list details {
  border: 1px solid rgba(127, 219, 255, 0.3);
  border-radius: var(--radius);
  padding: 14px 18px;
}

.faq-list summary {
  cursor: pointer;
  font-weight: 500;
  color: var(--cyan);
}

.faq-list p {
  margin: 12px 0 0;
  color: var(--text-dim);
}

/* Images */
.shot {
  margin: 0 auto;
  max-width: 900px;
  padding: 0 20px;
}

.shot img {
  display: block;
  margin: 0 auto;
  max-width: 100%;
  height: auto;
  border: 1px solid rgba(127, 219, 255, 0.35);
}

.shot figcaption {
  font-size: 0.88rem;
  color: var(--text-dim);
  margin-top: 8px;
  text-align: center;
}

/* CTA block (bottom) */
.cta-block {
  background: var(--navy-deep);
  border-top: 1px solid rgba(127, 219, 255, 0.25);
}

.cta-heading {
  font-family: 'Space Mono', monospace;
  color: var(--cyan);
  font-size: 1.25rem;
  margin: 0 0 12px;
}

.cta-block p { color: var(--text-dim); }

/* Related links */
.related-heading {
  font-family: 'Space Mono', monospace;
  color: var(--cyan);
  font-size: 1.2rem;
  margin: 0 0 16px;
}

.related-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 10px;
}

.related-list a {
  display: block;
  border: 1px solid rgba(127, 219, 255, 0.3);
  border-radius: var(--radius);
  padding: 14px 18px;
  text-decoration: none;
  color: var(--text);
  font-weight: 500;
}

.related-list a:hover {
  background: rgba(127, 219, 255, 0.1);
  color: var(--cyan);
}

/* Footer */
footer {
  background: var(--navy-deep);
  color: var(--text-dim);
  border-top: 1px solid rgba(127, 219, 255, 0.25);
}

footer address {
  font-style: normal;
  line-height: 1.8;
}

footer small {
  display: block;
  margin-top: 16px;
  opacity: 0.75;
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}