:root {
  --bg: #F4F1EA;
  --paper: #FFFFFF;
  --ink: #111111;
  --accent: #3D7AB8;
  --accent-dark: #1E3A5F;
  --warn: #E0A880;
  --ok: #4CAF93;
  --line: #111111;
  --shadow: 4px 4px 0 var(--accent);
  --shadow-lg: 8px 8px 0 var(--accent);
  --shadow-dark: 4px 4px 0 var(--ink);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  background-image:
    radial-gradient(circle at 1px 1px, rgba(17,17,17,0.08) 1px, transparent 0);
  background-size: 24px 24px;
}

/* ---------- NAVBAR (Brutalist #09) ---------- */
.navbar {
  background: var(--paper);
  border-bottom: 2px solid var(--ink);
  box-shadow: var(--shadow);
  padding: 18px 28px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
}

body { padding-top: 80px; }

.logo {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 1.6rem;
  letter-spacing: -0.03em;
  color: #111;
  text-transform: uppercase;
}
.logo .accent { color: var(--accent); }

.nav-links {
  display: flex;
  gap: 4px;
  list-style: none;
}
.nav-links a {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--ink);
  font-size: 0.82rem;
  letter-spacing: 0.02em;
  padding: 8px 14px;
  border: 2px solid transparent;
  transition: all 0.12s ease;
}
.nav-links a:hover {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}

/* ---------- HERO ---------- */
.hero {
  max-width: 1200px;
  margin: 40px auto 24px;
  padding: 0 24px;
}

.hero-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 18px;
  display: inline-block;
  padding: 4px 10px;
  background: var(--paper);
  border: 2px solid var(--ink);
}

.hero h1 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: clamp(2.4rem, 6vw, 4.8rem);
  line-height: 0.95;
  letter-spacing: -0.035em;
  text-transform: uppercase;
  margin-bottom: 18px;
}
.hero h1 .accent { color: var(--accent); }
.hero h1 .plus {
  display: inline-block;
  transform: rotate(-8deg);
  color: var(--ink);
  margin: 0 8px;
}

.hero p.lede {
  font-size: 1.12rem;
  max-width: 720px;
  color: #333;
  margin-bottom: 28px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}
.meta-chip {
  background: var(--paper);
  border: 2px solid var(--ink);
  padding: 8px 14px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.meta-chip strong { color: var(--accent); }

/* ---------- BACK LINK ---------- */
.hero-back {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  text-decoration: none;
  color: var(--ink);
  background: #ffd9a8;
  border: 2px solid var(--ink);
  padding: 8px 16px;
  display: block;
  width: fit-content;
  margin-bottom: 20px;
  box-shadow: 3px 3px 0 var(--ink);
}
.hero-back:hover { background: #ffc580; }

/* ---------- GEAR DIAGRAM ---------- */
.topology {
  max-width: 1200px;
  margin: 40px auto;
  padding: 0 24px;
}
.topology-card {
  background: var(--paper);
  border: 2px solid var(--ink);
  box-shadow: var(--shadow);
  padding: 32px;
}
.topology-card h2 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: -0.02em;
  font-size: 1.4rem;
  margin-bottom: 20px;
  border-bottom: 2px solid var(--ink);
  padding-bottom: 10px;
}

.topology-diagram {
  display: flex;
  align-items: center;
  justify-content: space-around;
  flex-wrap: wrap;
  gap: 20px;
  padding: 20px 0;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
}
.device-box {
  background: var(--bg);
  border: 2px solid var(--ink);
  padding: 16px 20px;
  text-align: center;
  min-width: 140px;
  box-shadow: 3px 3px 0 var(--ink);
}
.device-box .icon { font-size: 1.8rem; display: block; margin-bottom: 6px; }
.device-box .label { font-weight: 700; text-transform: uppercase; font-size: 0.78rem; }
.device-box .sub { font-size: 0.72rem; color: #666; margin-top: 4px; }
.device-box.accent { background: var(--accent); color: white; }
.device-box.accent .sub { color: rgba(255,255,255,0.85); }

.arrow {
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  color: var(--accent);
  font-size: 1.2rem;
}
.arrow-label {
  font-size: 0.7rem;
  color: #666;
  display: block;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* ---------- PROGRESS BAR ---------- */
.progress-wrap {
  max-width: 1200px;
  margin: 40px auto 20px;
  padding: 0 24px;
}
.progress-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 10px;
}
.progress-header span {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}
.progress-bar {
  height: 8px;
  background: var(--paper);
  border: 2px solid var(--ink);
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--accent);
  width: 0;
  transition: width 0.4s ease;
}

/* ---------- STEPS ---------- */
.steps {
  max-width: 1200px;
  margin: 0 auto 80px;
  padding: 0 24px;
}

.step {
  background: var(--paper);
  border: 2px solid var(--ink);
  box-shadow: var(--shadow);
  margin-bottom: 28px;
  overflow: hidden;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.step:hover {
  transform: translate(-2px, -2px);
  box-shadow: var(--shadow-lg);
}

.step-header {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 20px 24px;
  background: var(--bg);
  border-bottom: 2px solid var(--ink);
}
.step-number {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 2.2rem;
  line-height: 1;
  color: var(--accent);
  letter-spacing: -0.05em;
  min-width: 60px;
}
.step-title-block h3 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: -0.02em;
  font-size: 1.25rem;
  line-height: 1.2;
}
.step-title-block .dev-tag {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: #666;
  margin-top: 4px;
  display: inline-block;
  padding: 2px 8px;
  background: var(--paper);
  border: 1px solid var(--ink);
}
.dev-tag.router { color: var(--accent-dark); border-color: var(--accent-dark); }
.dev-tag.switch { color: #8B6D4A; border-color: #8B6D4A; }
.dev-tag.both { color: var(--ok); border-color: var(--ok); }

.step-body {
  padding: 24px 28px;
}
.step-body p { margin-bottom: 14px; }
.step-body ul, .step-body ol {
  margin: 10px 0 16px 22px;
}
.step-body li { margin-bottom: 6px; }

/* ---------- CODE BLOCKS ---------- */
.code-block {
  background: #0f1419;
  color: #e4e4e4;
  border: 2px solid var(--ink);
  padding: 18px 22px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.86rem;
  line-height: 1.55;
  margin: 14px 0;
  overflow-x: auto;
  position: relative;
  box-shadow: 3px 3px 0 var(--accent);
  white-space: pre;
}
.code-block::before {
  content: attr(data-label);
  position: absolute;
  top: 0;
  right: 0;
  background: var(--accent);
  color: white;
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  padding: 3px 10px;
  font-weight: 700;
}
.code-block .comment { color: #7a8a9a; font-style: italic; }
.code-block .cmd { color: #88c0d0; }
.code-block .str { color: #a3be8c; }
.code-block .num { color: #d08770; }
.code-block .kw { color: #ebcb8b; }
.code-block .prompt { color: #b48ead; user-select: none; }

.copy-btn {
  position: absolute;
  top: 30px;
  right: 0;
  background: transparent;
  color: #e4e4e4;
  border: 1px solid #3a4552;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  padding: 3px 8px;
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  transition: all 0.12s;
}
.copy-btn:hover { background: var(--accent); border-color: var(--accent); }
.copy-btn.copied { background: var(--ok); border-color: var(--ok); }

/* ---------- CALLOUTS ---------- */
.callout {
  border: 2px solid var(--ink);
  padding: 14px 18px;
  margin: 16px 0;
  display: flex;
  gap: 12px;
  align-items: flex-start;
}
.callout .ico {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid var(--ink);
  background: var(--ink);
  color: var(--paper);
  font-size: 0.9rem;
}
.callout.tip { background: #DCE9F7; }
.callout.tip .ico { background: var(--accent); border-color: var(--accent); }
.callout.warn { background: #F9E3D0; }
.callout.warn .ico { background: #C96B65; border-color: #C96B65; }
.callout.note { background: #F0EDE3; }
.callout strong { font-family: 'Syne', sans-serif; text-transform: uppercase; letter-spacing: 0.02em; }

/* ---------- CHECKLIST ---------- */
.checklist {
  list-style: none;
  margin: 12px 0 !important;
  padding-left: 0 !important;
}
.checklist li {
  padding: 8px 12px;
  border: 2px solid var(--ink);
  background: var(--bg);
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  transition: all 0.15s;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
}
.checklist li::before {
  content: '';
  display: block;
  width: 18px;
  height: 18px;
  border: 2px solid var(--ink);
  background: var(--paper);
  flex-shrink: 0;
}
.checklist li.done {
  background: var(--ok);
  color: var(--paper);
}
.checklist li.done::before {
  background: var(--ink);
  content: '✓';
  color: var(--paper);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.8rem;
}

/* ---------- TABLES ---------- */
.spec-table {
  width: 100%;
  border-collapse: collapse;
  margin: 14px 0;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  border: 2px solid var(--ink);
}
.spec-table th, .spec-table td {
  padding: 10px 14px;
  border-bottom: 1px solid #ddd;
  text-align: left;
}
.spec-table th {
  background: var(--ink);
  color: var(--paper);
  text-transform: uppercase;
  font-size: 0.72rem;
  letter-spacing: 0.1em;
}
.spec-table tr:last-child td { border-bottom: none; }
.spec-table tr:hover td { background: var(--bg); }

/* ---------- MONO NOTE ---------- */
.mono-note {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
}

/* ---------- FOOTER ---------- */
footer {
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 24px 60px;
  border-top: 2px solid var(--ink);
  margin-top: 40px;
}
footer .foot-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 40px;
}
footer h4 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: -0.02em;
  margin-bottom: 10px;
}
footer p { font-size: 0.9rem; color: #444; }
footer .sig {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-top: 16px;
}

/* ---------- RESPONSIVE ---------- */
@media (max-width: 720px) {
  .navbar { flex-direction: column; gap: 14px; padding: 14px; }
  body { padding-top: 140px; }
  .nav-links { flex-wrap: wrap; justify-content: center; }
  .hero { padding: 0 16px; }
  .topology { padding: 0 16px; }
  .topology-card { padding: 20px; }
  .steps { padding: 0 16px; }
  .step-header { flex-direction: column; text-align: center; padding: 16px; }
  .step-body { padding: 18px; }
  .code-block { font-size: 0.75rem; padding: 14px; }
  footer .foot-grid { grid-template-columns: 1fr; }
  .arrow { display: none; }
}