:root {
  --bg: #fbfcfd;
  --bg-alt: #f1f4f7;
  --surface: #ffffff;
  --ink: #0f1b2a;
  --muted: #4f5d6d;
  --faint: #8593a3;
  --line: #dde3ea;
  --grid: rgba(15, 27, 42, 0.045);
  --accent: #0b6784;       /* acoustic */
  --accent-dark: #084e65;
  --laser: #b8472a;        /* optical */
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --max: 1100px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg);
}

a { color: var(--accent); }
a:hover { color: var(--accent-dark); }

.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 20px;
}

.mono {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--faint);
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(251, 252, 253, 0.94);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--line);
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding-top: 14px;
  padding-bottom: 14px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 650;
  font-size: 1.1rem;
  color: var(--ink);
  text-decoration: none;
}
.logo img { width: 30px; height: 30px; }
.nav { display: flex; flex-wrap: wrap; gap: 22px; }
.nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.93rem;
}
.nav a:hover { color: var(--accent); }

/* Hero */
.hero {
  padding: 88px 0 64px;
  border-bottom: 1px solid var(--line);
  background-color: var(--bg);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
}
.hero h1 {
  font-size: clamp(2rem, 4.6vw, 2.9rem);
  line-height: 1.15;
  font-weight: 650;
  letter-spacing: -0.01em;
  margin: 12px 0 18px;
  max-width: 780px;
}
.hero p {
  font-size: 1.12rem;
  color: var(--muted);
  max-width: 660px;
  margin: 0 0 30px;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; }

.figure {
  margin: 48px 0 0;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 16px 20px 12px;
}
.figure svg { display: block; width: 100%; height: auto; }
.figure figcaption {
  margin-top: 8px;
  font-size: 0.85rem;
  color: var(--muted);
}
.figure figcaption b { font-family: var(--mono); font-weight: 600; color: var(--ink); }

.btn {
  display: inline-block;
  padding: 11px 22px;
  border-radius: 4px;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid var(--accent);
}
.btn:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #fff; }
.btn-outline { background: transparent; color: var(--accent); }
.btn-outline:hover { background: var(--bg-alt); color: var(--accent-dark); }

/* Sections */
section { padding: 72px 0; }
section.alt { background: var(--bg-alt); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
section h2 {
  font-size: 1.85rem;
  font-weight: 650;
  letter-spacing: -0.01em;
  margin: 8px 0 12px;
}
.lead {
  color: var(--muted);
  max-width: 720px;
  margin: 0 0 36px;
}

/* Technique panels */
.technique {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}
.panel {
  background: var(--surface);
  border: 1px solid var(--line);
  border-top: 3px solid var(--accent);
  border-radius: 4px;
  padding: 24px;
}
.panel.laser { border-top-color: var(--laser); }
.panel h3 { margin: 4px 0 12px; font-size: 1.15rem; }
.panel ul { margin: 0; padding-left: 18px; color: var(--muted); }
.panel li { margin-bottom: 6px; }
.panel .std {
  margin: 16px 0 0;
  padding-top: 12px;
  border-top: 1px dashed var(--line);
  font-size: 0.86rem;
  color: var(--faint);
}

.principle {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--surface);
  margin-bottom: 32px;
}
.principle div {
  padding: 18px 20px;
  border-right: 1px solid var(--line);
}
.principle div:last-child { border-right: none; }
.principle h4 { margin: 4px 0 4px; font-size: 1rem; }
.principle p { margin: 0; font-size: 0.93rem; color: var(--muted); }

/* Parameter table */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: 4px; background: var(--surface); }
table { width: 100%; border-collapse: collapse; font-size: 0.93rem; min-width: 640px; }
th, td { text-align: left; padding: 12px 16px; border-bottom: 1px solid var(--line); vertical-align: top; }
th {
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--faint);
  font-weight: 500;
  background: var(--bg-alt);
}
tr:last-child td { border-bottom: none; }
td:first-child { font-weight: 600; white-space: nowrap; }
td { color: var(--muted); }
td:first-child { color: var(--ink); }

/* Steps */
.steps {
  list-style: none;
  counter-reset: step;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 28px;
}
.steps li { counter-increment: step; border-left: 1px solid var(--line); padding-left: 18px; }
.steps li::before {
  content: "0" counter(step);
  display: block;
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--accent);
  margin-bottom: 6px;
}
.steps h3 { margin: 0 0 6px; font-size: 1.05rem; }
.steps p { margin: 0; color: var(--muted); font-size: 0.95rem; }

/* Two column */
.two-col {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 40px;
  align-items: start;
}

.contact-box {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 28px;
}
.contact-box dl { margin: 0; }
.contact-box dt {
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--faint);
  margin-top: 16px;
}
.contact-box dt:first-child { margin-top: 0; }
.contact-box dd { margin: 2px 0 0; }

/* Footer */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 26px 0;
  font-size: 0.88rem;
  color: var(--muted);
}
.site-footer .container {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px;
}

/* 404 */
.simple-page {
  min-height: 60vh;
  display: flex;
  align-items: center;
  text-align: center;
}
.simple-page .container { width: 100%; }
.simple-page .lead { margin: 0 auto 28px; }

@media (max-width: 860px) {
  .steps { grid-template-columns: repeat(2, 1fr); }
  .principle { grid-template-columns: repeat(2, 1fr); }
  .principle div:nth-child(2) { border-right: none; }
  .principle div:nth-child(-n+2) { border-bottom: 1px solid var(--line); }
}

@media (max-width: 600px) {
  .steps { grid-template-columns: 1fr; }
  .principle { grid-template-columns: 1fr; }
  body { font-size: 16px; }
  .nav { gap: 14px; }
  .hero { padding: 56px 0 44px; }
  section { padding: 52px 0; }
  .principle div { border-right: none; border-bottom: 1px solid var(--line); }
  .principle div:last-child { border-bottom: none; }
}