/* ponytail: 폰트 CDN 미검증으로 폴백 사용, 실제 폰트 라이선스 확보 후 교체 */

:root {
  --navy: #0F172A;
  --navy-soft: #1E293B;
  --white: #FFFFFF;
  --cyan: #06B6D4;
  --cyan-deep: #0B93AC;
  --ink: #1F2937;
  --muted: #52606D;
  --border: #E2E8F0;
  --surface: #F8FAFC;

  --font-head: 'Pretendard', 'Noto Sans KR', sans-serif;
  --font-body: 'Noto Sans KR', 'Pretendard', sans-serif;

  --radius: 4px;

  /* type scale ratio 1.333 */
  --fs-body: 1rem;
  --fs-sm: 0.875rem;
  --fs-h4: 1.333rem;
  --fs-h3: 1.777rem;
  --fs-h2: clamp(1.6rem, 1.3rem + 1.3vw, 2.369rem);
  --fs-h1: clamp(1.9rem, 1.4rem + 2.2vw, 3.157rem);

  --pad-section: 64px;
}

@media (min-width: 640px) {
  :root { --pad-section: 80px; }
}

@media (min-width: 1024px) {
  :root { --pad-section: 96px; }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.7;
  color: var(--ink);
  background: var(--white);
  overflow-x: hidden;
}

h1, h2, h3 {
  font-family: var(--font-head);
  color: var(--navy);
  line-height: 1.3;
  margin: 0 0 0.6em;
}

h1 { font-size: var(--fs-h1); font-weight: 800; }
h2 { font-size: var(--fs-h2); font-weight: 700; margin-top: 1.6em; }
h2:first-child { margin-top: 0; }
h3 { font-size: var(--fs-h3); font-weight: 700; }

p { margin: 0 0 1em; color: var(--ink); }

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px;
}

a { color: var(--cyan-deep); }
a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--cyan);
  outline-offset: 2px;
}

/* header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  height: 68px;
  background: var(--navy);
  border-bottom: 1px solid var(--navy-soft);
}

.header-inner {
  max-width: 960px;
  margin: 0 auto;
  height: 100%;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1.15rem;
  color: var(--white);
  letter-spacing: -0.01em;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-head);
  font-weight: 700;
  text-decoration: none;
  border-radius: var(--radius);
  padding: 10px 18px;
  border: 2px solid transparent;
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

@media (prefers-reduced-motion: reduce) {
  .btn { transition: none; }
}

.btn-header {
  background: var(--cyan);
  color: var(--navy);
  font-size: var(--fs-sm);
}
.btn-header:hover { background: #22D3EE; }

.btn-primary {
  background: var(--cyan);
  color: var(--navy);
}
.btn-primary:hover { background: var(--white); border-color: var(--cyan); }

.btn-lg { padding: 14px 28px; font-size: 1.05rem; }

/* hero */
.hero {
  position: relative;
  background: var(--navy);
  color: var(--white);
  overflow: hidden;
}

.hero-wall {
  width: 100%;
  line-height: 0;
}

.hero-wall svg {
  display: block;
  width: 100%;
  height: auto;
}

.hero-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 40px 20px 56px;
}

.hero h1 {
  color: var(--white);
  margin-bottom: 0.5em;
}

.hero-lede {
  color: #CBD5E1;
  font-size: 1.05rem;
  max-width: 640px;
  margin-bottom: 1.6em;
}

/* sections */
.section {
  padding: var(--pad-section) 0;
}

.section.axis { background: var(--surface); }

.problem p,
.axis p {
  max-width: 720px;
}

/* svg diagram */
.svg-wrap {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  overflow-x: auto;
}

.svg-wrap svg {
  display: block;
  min-width: 480px;
}

/* table */
.table-scroll {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 560px;
}

caption {
  text-align: left;
  padding: 12px 16px;
  font-weight: 700;
  color: var(--navy);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

th, td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
  font-size: var(--fs-sm);
  white-space: nowrap;
}

thead th {
  background: var(--navy);
  color: var(--white);
  font-family: var(--font-head);
}

tbody tr:last-child td { border-bottom: none; }
tbody tr:nth-child(even) { background: var(--surface); }

/* gallery */
.photo-grid {
  display: flex;
  flex-direction: column;
  gap: 20px;
  align-items: center;
}

.photo-grid figure {
  margin: 0;
  width: 100%;
  max-width: 360px;
}

.photo-grid picture,
.photo-grid img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 4;
  object-fit: cover;
  border-radius: var(--radius);
}

.photo-grid figcaption {
  margin-top: 8px;
  font-size: var(--fs-sm);
  color: var(--muted);
  text-align: center;
}

@media (min-width: 1024px) {
  .photo-grid {
    flex-direction: row;
    justify-content: center;
    align-items: flex-start;
  }
}

/* faq */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: 720px;
}

details {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 18px;
}

summary {
  font-weight: 700;
  color: var(--navy);
  cursor: pointer;
}

details p { margin-top: 10px; margin-bottom: 0; color: var(--muted); }

/* cta */
.cta-block {
  background: var(--navy);
  color: var(--white);
}

.cta-block h2 { color: var(--white); }

.cta-block p {
  color: #CBD5E1;
  max-width: 640px;
  margin-bottom: 1.6em;
}

/* footer */
.site-footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 40px 0;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  margin-bottom: 16px;
}

.footer-links a {
  font-size: var(--fs-sm);
  text-decoration: none;
}

.footer-links a:hover { text-decoration: underline; }

.footer-info {
  font-size: var(--fs-sm);
  color: var(--muted);
  margin: 0;
}