/* Style: Technical blueprint (navy drafting grid, cyan linework, IBM Plex) */
:root {
  --navy: #0b2545;
  --navy-2: #13315c;
  --cyan: #7fdbff;
  --paper: #f4f7fb;
  --ink: #0d1b2a;
  --muted: #4a5a70;
  --line: #c9d6e6;
  --accent: #ffb703;
  --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
}

*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--ink);
  background: var(--paper);
}

img, svg { max-width: 100%; height: auto; }

a { color: var(--navy-2); }

a:focus-visible, .btn:focus-visible, summary:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
}

.wrap { width: min(1120px, 100% - 32px); margin-inline: auto; }

.skip {
  position: absolute;
  left: -999px;
  top: 8px;
  padding: 8px 12px;
  background: var(--accent);
  color: var(--ink);
  z-index: 10;
}

.skip:focus { left: 8px; }

/* Top bar */
.topbar {
  background: var(--navy);
  color: #fff;
  border-bottom: 1px solid rgba(127, 219, 255, .3);
}

.topbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 60px;
}

.brand {
  font-family: var(--mono);
  font-weight: 600;
  color: #fff;
  text-decoration: none;
  letter-spacing: .04em;
}

.brand span { color: var(--cyan); margin-left: 4px; }

.nav { display: none; list-style: none; margin: 0; padding: 0; gap: 24px; }

.nav a { color: #dbe7f5; text-decoration: none; font-size: .95rem; }

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

/* Buttons */
.btn {
  display: inline-block;
  padding: 14px 22px;
  background: var(--accent);
  color: var(--ink);
  font-weight: 700;
  text-decoration: none;
  border: 2px solid var(--accent);
  border-radius: 2px;
}

.btn:hover { background: #ffc933; }

.btn--small { padding: 8px 14px; font-size: .9rem; }

.btn--ghost { background: transparent; color: #fff; border-color: var(--cyan); }

.btn--ghost:hover { background: rgba(127, 219, 255, .12); }

.btn--light { background: #fff; border-color: #fff; color: var(--navy); }

.btn--light:hover { background: var(--paper); }

/* Hero */
.hero {
  color: #fff;
  padding: 56px 0 64px;
  background-color: var(--navy);
  background-image:
    linear-gradient(rgba(127, 219, 255, .08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(127, 219, 255, .08) 1px, transparent 1px),
    linear-gradient(rgba(127, 219, 255, .04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(127, 219, 255, .04) 1px, transparent 1px);
  background-size: 80px 80px, 80px 80px, 16px 16px, 16px 16px;
}

.hero__grid { display: grid; gap: 40px; align-items: center; }

.tag {
  font-family: var(--mono);
  font-size: .8rem;
  color: var(--cyan);
  letter-spacing: .08em;
  text-transform: uppercase;
  margin: 0 0 12px;
}

h1 {
  font-size: clamp(2rem, 6vw, 3.25rem);
  line-height: 1.1;
  margin: 0 0 20px;
}

h1 em { font-style: normal; color: var(--cyan); }

.lede { font-size: 1.15rem; color: #dbe7f5; max-width: 60ch; margin: 0 0 28px; }

.cta-row { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 36px; }

.spec {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  list-style: none;
  padding: 0;
  margin: 0;
  border: 1px solid rgba(127, 219, 255, .4);
  background: rgba(127, 219, 255, .4);
}

.spec li { background: var(--navy); padding: 12px 14px; font-weight: 600; }

.spec span {
  display: block;
  font-family: var(--mono);
  font-size: .72rem;
  font-weight: 400;
  color: var(--cyan);
  text-transform: uppercase;
  letter-spacing: .08em;
}

.diagram {
  margin: 0;
  padding: 16px;
  color: var(--cyan);
  border: 1px solid rgba(127, 219, 255, .5);
  background: rgba(11, 37, 69, .6);
}

.diagram svg { display: block; width: 100%; }

.diagram figcaption {
  font-family: var(--mono);
  font-size: .78rem;
  color: #b8cde3;
  margin-top: 8px;
}

/* Sections */
.section { padding: 64px 0; }

.band { padding: 56px 0; background: #fff; border-block: 1px solid var(--line); }

.band--dark { background: var(--navy-2); color: #fff; border: 0; }

.band--dark a { color: var(--cyan); }

h2 {
  font-size: clamp(1.5rem, 4vw, 2.1rem);
  line-height: 1.2;
  margin: 0 0 16px;
}

.num {
  font-family: var(--mono);
  font-size: .9rem;
  color: var(--accent);
  border: 1px solid currentColor;
  padding: 2px 6px;
  margin-right: 8px;
  vertical-align: middle;
}

.muted { color: var(--muted); margin-top: 0; }

.two-col { display: grid; gap: 32px; }

.checklist { list-style: none; margin: 0; padding: 0; }

.checklist li {
  position: relative;
  padding: 12px 0 12px 32px;
  border-bottom: 1px dashed var(--line);
}

.checklist li::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 19px;
  width: 12px;
  height: 7px;
  border-left: 2px solid var(--navy-2);
  border-bottom: 2px solid var(--navy-2);
  transform: rotate(-45deg);
}

/* Modules */
.modules {
  counter-reset: mod;
  list-style: none;
  padding: 0;
  margin: 32px 0 0;
  display: grid;
  gap: 16px;
}

.modules li {
  counter-increment: mod;
  background: #fff;
  border: 1px solid var(--line);
  border-top: 3px solid var(--navy-2);
  padding: 20px 20px 16px;
}

.modules li::before {
  content: "MOD " counter(mod, decimal-leading-zero);
  font-family: var(--mono);
  font-size: .75rem;
  color: var(--muted);
  letter-spacing: .1em;
}

.modules h3 { font-size: 1.1rem; margin: 4px 0 6px; }

.modules p { margin: 0; color: var(--muted); font-size: .97rem; }

/* Facts */
.facts {
  display: grid;
  gap: 1px;
  margin: 28px 0;
  background: rgba(127, 219, 255, .35);
  border: 1px solid rgba(127, 219, 255, .35);
}

.facts div { background: var(--navy-2); padding: 16px; }

.facts dt {
  font-family: var(--mono);
  font-size: .75rem;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--cyan);
}

.facts dd { margin: 4px 0 0; font-weight: 600; }

.formats { color: #dbe7f5; max-width: 75ch; margin: 0; }

/* Objectives */
.objectives {
  columns: 1;
  column-gap: 40px;
  padding-left: 20px;
  margin: 24px 0 0;
}

.objectives li { margin-bottom: 10px; break-inside: avoid; }

/* FAQ */
.faq { margin-top: 24px; border-top: 1px solid var(--line); }

.faq details { border-bottom: 1px solid var(--line); }

.faq summary {
  cursor: pointer;
  padding: 18px 32px 18px 0;
  font-weight: 600;
  list-style: none;
  position: relative;
}

.faq summary::-webkit-details-marker { display: none; }

.faq summary::after {
  content: "+";
  position: absolute;
  right: 4px;
  top: 14px;
  font-family: var(--mono);
  font-size: 1.4rem;
  color: var(--navy-2);
}

.faq details[open] summary::after { content: "−"; }

.faq details p { margin: 0 0 18px; color: var(--muted); max-width: 75ch; }

/* Final CTA */
.final { background: var(--navy); color: #fff; padding: 64px 0; text-align: center; }

.final__inner p { color: #dbe7f5; margin: 0 0 24px; }

/* Footer */
.footer { background: var(--ink); color: #b8cde3; padding: 28px 0; font-size: .9rem; }

.footer a { color: #fff; }

.footer__inner { display: grid; gap: 4px; }

.footer p { margin: 0; }

@media (min-width: 720px) {
  .nav { display: flex; }
  .spec { grid-template-columns: repeat(4, 1fr); }
  .two-col { grid-template-columns: 1fr 1.2fr; align-items: start; }
  .modules { grid-template-columns: repeat(2, 1fr); }
  .facts { grid-template-columns: repeat(2, 1fr); }
  .objectives { columns: 2; }
  .footer__inner { grid-template-columns: 1fr auto; }
}

@media (min-width: 1000px) {
  .hero__grid { grid-template-columns: 1.3fr 1fr; }
  .modules { grid-template-columns: repeat(3, 1fr); }
  .facts { grid-template-columns: repeat(4, 1fr); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}