:root {
  --bg: #0b0f14;
  --bg-elev: #121820;
  --bg-card: #161d27;
  --border: #243041;
  --text: #e8eef6;
  --muted: #8b9bb0;
  --accent: #00e5ff;
  --accent-2: #ff9800;
  --accent-3: #e040fb;
  --ok: #76ff03;
  --warn: #ffea00;
  --danger: #ff1744;
  --link: #7dd3fc;
  --radius: 12px;
  --font: "Segoe UI", system-ui, -apple-system, sans-serif;
  --mono: "JetBrains Mono", "Fira Code", ui-monospace, monospace;
  --max: 1100px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; color: var(--accent); }
img { max-width: 100%; height: auto; }
code, pre { font-family: var(--mono); font-size: 0.9em; }
pre {
  background: #0a0e13;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  overflow-x: auto;
}

.skip { position: absolute; left: -9999px; }
.skip:focus { left: 1rem; top: 1rem; background: var(--accent); color: #000; padding: .5rem 1rem; z-index: 99; }

/* Nav */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(11,15,20,.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: .75rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.logo {
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--text);
  display: flex; align-items: center; gap: .5rem;
  text-decoration: none;
}
.logo span { color: var(--accent); }
.logo:hover { text-decoration: none; }
.nav-toggle {
  display: none;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text);
  padding: .45rem .75rem;
  border-radius: 8px;
  cursor: pointer;
}
.nav-links {
  display: flex; flex-wrap: wrap; gap: .25rem 1.1rem;
  list-style: none; margin: 0; padding: 0;
}
.nav-links a {
  color: var(--muted);
  font-size: .95rem;
  font-weight: 500;
  text-decoration: none;
}
.nav-links a:hover, .nav-links a.active { color: var(--accent); }

@media (max-width: 760px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    position: absolute;
    left: 0; right: 0; top: 100%;
    background: var(--bg-elev);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 1rem 1.25rem;
    gap: .75rem;
  }
  .nav-links.open { display: flex; }
}

/* Layout */
main { flex: 1; }
.container { max-width: var(--max); margin: 0 auto; padding: 2rem 1.25rem 3.5rem; }
.narrow { max-width: 760px; }

.hero {
  padding: 3.5rem 0 2.5rem;
  background:
    radial-gradient(ellipse 80% 60% at 20% -10%, rgba(0,229,255,.12), transparent),
    radial-gradient(ellipse 60% 50% at 90% 10%, rgba(224,64,251,.08), transparent);
  border-bottom: 1px solid var(--border);
}
.hero h1 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  line-height: 1.2;
  margin: 0 0 1rem;
}
.hero .lead {
  font-size: 1.15rem;
  color: var(--muted);
  max-width: 42rem;
  margin: 0 0 1.75rem;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: .75rem; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: .7rem 1.2rem;
  border-radius: 10px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  font-size: .95rem;
}
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--accent); color: #041018; }
.btn-primary:hover { filter: brightness(1.08); color: #041018; }
.btn-ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }
.btn-sm { padding: .45rem .85rem; font-size: .85rem; }

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}
@media (max-width: 800px) {
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.35rem 1.4rem;
}
.card h3 { margin: 0 0 .5rem; font-size: 1.1rem; }
.card p { margin: 0; color: var(--muted); font-size: .95rem; }
.card .tag {
  display: inline-block;
  font-size: .75rem;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--accent);
  margin-bottom: .5rem;
}

.section-title {
  font-size: 1.5rem;
  margin: 0 0 .35rem;
}
.section-sub { color: var(--muted); margin: 0 0 1.5rem; }

.page-header { margin-bottom: 2rem; }
.page-header h1 { margin: 0 0 .5rem; font-size: clamp(1.6rem, 3vw, 2.1rem); }
.page-header p { margin: 0; color: var(--muted); }

.meta {
  display: flex; flex-wrap: wrap; gap: .5rem 1rem;
  color: var(--muted); font-size: .9rem; margin-bottom: 1.5rem;
}
.badge {
  display: inline-block;
  background: rgba(0,229,255,.12);
  color: var(--accent);
  border: 1px solid rgba(0,229,255,.25);
  padding: .15rem .55rem;
  border-radius: 999px;
  font-size: .8rem;
}

.prose h2 { margin-top: 2rem; font-size: 1.35rem; border-bottom: 1px solid var(--border); padding-bottom: .4rem; }
.prose h3 { margin-top: 1.5rem; font-size: 1.1rem; color: var(--accent); }
.prose p, .prose li { color: #c5d0dc; }
.prose ul, .prose ol { padding-left: 1.25rem; }
.prose blockquote {
  margin: 1.25rem 0;
  padding: .75rem 1rem;
  border-left: 3px solid var(--accent);
  background: rgba(0,229,255,.06);
  color: var(--muted);
}
.takeaways {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.4rem;
  margin: 2rem 0;
}
.takeaways h3 { margin: 0 0 .75rem; color: var(--ok); }
.takeaways ul { margin: 0; }

table {
  width: 100%;
  border-collapse: collapse;
  font-size: .9rem;
  margin: 1rem 0 1.5rem;
}
th, td {
  border: 1px solid var(--border);
  padding: .55rem .7rem;
  text-align: left;
}
th { background: var(--bg-elev); color: var(--accent); font-weight: 600; }
td { color: #c5d0dc; }
.table-wrap { overflow-x: auto; }

.lesson-nav {
  display: flex; justify-content: space-between; gap: 1rem;
  margin-top: 2.5rem; padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
}
.module-list { list-style: none; padding: 0; margin: 0; }
.module-list li {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: .75rem;
  background: var(--bg-card);
}
.module-list a {
  display: block;
  padding: 1.1rem 1.25rem;
  color: var(--text);
  text-decoration: none;
}
.module-list a:hover { background: rgba(0,229,255,.05); }
.module-list .num { color: var(--accent); font-weight: 700; margin-right: .5rem; }
.module-list .desc { display: block; color: var(--muted); font-size: .9rem; margin-top: .25rem; }

/* Tools */
.tool-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.75rem;
}
.tool-panel h2 { margin: 0 0 .35rem; font-size: 1.25rem; }
.tool-panel .hint { color: var(--muted); margin: 0 0 1.25rem; font-size: .9rem; }
.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 1rem;
}
@media (max-width: 600px) { .form-row { grid-template-columns: 1fr; } }
label { display: block; font-size: .85rem; color: var(--muted); margin-bottom: .35rem; }
input, textarea, select {
  width: 100%;
  background: #0a0e13;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  padding: .65rem .75rem;
  font: inherit;
}
input:focus, textarea:focus, select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(0,229,255,.15);
}
textarea { min-height: 100px; resize: vertical; font-family: var(--mono); font-size: .85rem; }
.tool-result {
  margin-top: 1rem;
  padding: 1rem;
  background: #0a0e13;
  border: 1px solid var(--border);
  border-radius: 8px;
  min-height: 3rem;
}
.tool-result strong { color: var(--accent); }
.phase-bar {
  height: 10px;
  background: #1a2330;
  border-radius: 999px;
  overflow: hidden;
  margin: .75rem 0;
}
.phase-bar > i {
  display: block; height: 100%;
  background: linear-gradient(90deg, var(--ok), var(--warn), var(--danger));
  width: 0%;
  border-radius: 999px;
}

.diagram {
  background: #0a0e13;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.25rem;
  margin: 1.25rem 0;
  font-family: var(--mono);
  font-size: .8rem;
  color: var(--muted);
  white-space: pre;
  overflow-x: auto;
  line-height: 1.4;
}

.script-card .actions { margin-top: 1rem; display: flex; flex-wrap: wrap; gap: .5rem; }
.footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 1.25rem;
  color: var(--muted);
  font-size: .85rem;
  text-align: center;
}
.footer a { color: var(--muted); }
.disclaimer {
  font-size: .8rem;
  color: #6b7a8d;
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

.features { margin: 2.5rem 0; }
.cta-band {
  margin: 2.5rem 0 0;
  padding: 2rem;
  border-radius: var(--radius);
  background: linear-gradient(135deg, rgba(0,229,255,.1), rgba(224,64,251,.08));
  border: 1px solid var(--border);
  text-align: center;
}
.cta-band h2 { margin: 0 0 .5rem; }
.cta-band p { color: var(--muted); margin: 0 0 1.25rem; }

.analysis-list { list-style: none; padding: 0; margin: 0; }
.analysis-list li {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 1rem;
  background: var(--bg-card);
}
.analysis-list a {
  display: block;
  padding: 1.25rem 1.4rem;
  color: inherit;
  text-decoration: none;
}
.analysis-list a:hover { border-color: var(--accent); }
.analysis-list h3 { margin: 0 0 .4rem; color: var(--text); }
.analysis-list p { margin: 0; color: var(--muted); font-size: .95rem; }