/* =========================================================
   VR.NET.TR Satellite Site — Corporate Infrastructure Theme
   Pure CSS3 — no frameworks, no external dependencies
   ========================================================= */

:root {
  /* Color tokens */
  --color-bg: #f6f8fa;
  --color-surface: #ffffff;
  --color-surface-alt: #eef2f5;
  --color-primary: #0b3d5c;
  --color-primary-dark: #072b40;
  --color-accent: #1E8FA6;
  --color-accent-dark: #146B7D;
  --color-text: #16232c;
  --color-text-muted: #526270;
  --color-border: #dde4ea;
  --color-code-bg: #0b3d5c;

  /* Type */
  --font-display: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-body: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Consolas, "Liberation Mono", Menlo, monospace;

  /* Layout */
  --max-width: 1200px;
  --radius: 6px;
  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2.5rem;
  --space-5: 4rem;
  --space-6: 6rem;
}

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

body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.65;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }

a { color: var(--color-accent-dark); text-decoration: none; }
a:hover { text-decoration: underline; }

a:focus-visible,
button:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
}

.wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-3);
}

/* ---------- Eyebrow / node labels (signature element) ---------- */
.node-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--color-accent-dark);
  text-transform: uppercase;
  margin-bottom: var(--space-1);
}
.node-tag::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-accent) 25%, transparent);
}

/* ---------- Top informative banner ---------- */
.top-banner {
  background: var(--color-primary-dark);
  color: #dce8f0;
  font-size: 0.9rem;
  padding: 0.55rem 0;
  border-bottom: 1px solid var(--color-primary);
}
.top-banner .wrap { display: flex; justify-content: space-between; align-items: center; gap: var(--space-2); flex-wrap: wrap; }
.top-banner a { color: #ffffff; font-weight: 600; }
.top-banner strong { color: #9fd3e0; font-weight: 600; }

/* ---------- Header / nav ---------- */
header.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 20;
}
.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-2);
  padding-bottom: var(--space-2);
  gap: var(--space-2);
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--color-primary);
}
.brand svg { flex-shrink: 0; }
nav.site-nav ul {
  list-style: none;
  display: flex;
  gap: var(--space-3);
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
}
nav.site-nav a {
  color: var(--color-text-muted);
  font-size: 0.92rem;
  font-weight: 500;
}
nav.site-nav a:hover { color: var(--color-accent-dark); }

/* ---------- Hero ---------- */
.hero {
  background:
    linear-gradient(180deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
  color: #eaf2f6;
  padding: var(--space-6) 0 var(--space-5);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(color-mix(in srgb, #ffffff 6%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, #ffffff 6%, transparent) 1px, transparent 1px);
  background-size: 42px 42px;
  mask-image: radial-gradient(ellipse at top right, black 0%, transparent 70%);
  pointer-events: none;
}
.hero .wrap { position: relative; }
.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4.2vw, 3rem);
  line-height: 1.15;
  font-weight: 700;
  margin: 0 0 var(--space-2);
  max-width: 20ch;
  letter-spacing: -0.01em;
}
.hero p.lead {
  font-size: 1.15rem;
  color: #cfe2ea;
  max-width: 62ch;
  margin: 0 0 var(--space-3);
}
.hero .node-tag { color: #9fd3e0; }
.hero .node-tag::before { background: #9fd3e0; box-shadow: 0 0 0 3px rgba(159,211,224,0.25); }

.hero-meta {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
  margin-top: var(--space-4);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: #b9d4de;
}
.hero-meta span { display: flex; align-items: center; gap: 0.4em; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 0.85rem 1.8rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.3s ease;
}
.btn-primary {
  background: var(--color-accent);
  color: #06222c;
  box-shadow: 0 4px 6px rgba(30, 143, 166, 0.2);
}
.btn-primary:hover { 
  background: var(--color-accent-dark); 
  color: #ffffff; 
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 8px 15px rgba(30, 143, 166, 0.3);
}
.btn-outline {
  background: transparent;
  border-color: color-mix(in srgb, #ffffff 35%, transparent);
  color: #eaf2f6;
}
.btn-outline:hover { background: color-mix(in srgb, #ffffff 10%, transparent); text-decoration: none; }

/* ---------- Sections ---------- */
main { display: block; }
section { padding: var(--space-5) 0; }
section.alt { background: var(--color-surface); border-top: 1px solid var(--color-border); border-bottom: 1px solid var(--color-border); }

.section-head { max-width: 70ch; margin-bottom: var(--space-4); }
h2 {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 2.6vw, 2rem);
  font-weight: 700;
  color: var(--color-primary);
  margin: 0 0 0.5rem;
  letter-spacing: -0.01em;
}
h3 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin: var(--space-3) 0 0.5rem;
}
p { color: var(--color-text); margin: 0 0 1rem; }
.section-head p { color: var(--color-text-muted); }

/* ---------- Table of contents ---------- */
.toc {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
}
.toc h2 { font-size: 1.15rem; margin-bottom: 0.75rem; }
.toc ol {
  columns: 2;
  column-gap: var(--space-4);
  margin: 0;
  padding-left: 1.2rem;
}
.toc li { break-inside: avoid; margin-bottom: 0.5rem; }
.toc a { color: var(--color-text); font-size: 0.95rem; }
.toc a:hover { color: var(--color-accent-dark); }
@media (max-width: 640px) { .toc ol { columns: 1; } }

/* ---------- Cards / grids ---------- */
.grid { display: grid; gap: var(--space-3); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 800px) { .grid-2, .grid-3 { grid-template-columns: 1fr; } }

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-4);
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 30px rgba(11, 61, 92, 0.12);
}
.card .node-tag { margin-bottom: var(--space-1); }
.card h3 { margin-top: 0; }
.card p:last-child { margin-bottom: 0; }

/* ---------- Definition / callout ---------- */
.callout {
  border-left: 3px solid var(--color-accent);
  background: var(--color-surface-alt);
  padding: var(--space-2) var(--space-3);
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: var(--space-2) 0;
}
.callout p:last-child { margin-bottom: 0; }

/* ---------- Code / tech spec blocks ---------- */
.spec-block {
  background: var(--color-code-bg);
  color: #dbe9f0;
  border-radius: var(--radius);
  padding: var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  overflow-x: auto;
}
.spec-block .k { color: #9fd3e0; }
.spec-block div { margin-bottom: 0.35rem; }
.spec-block div:last-child { margin-bottom: 0; }

/* ---------- Mistakes / best practices lists ---------- */
.check-list, .cross-list { list-style: none; margin: 0; padding: 0; }
.check-list li, .cross-list li {
  position: relative;
  padding-left: 1.8rem;
  margin-bottom: 0.9rem;
  color: var(--color-text);
}
.check-list li::before {
  content: "✓";
  position: absolute; left: 0; top: 0.05em;
  color: var(--color-accent-dark);
  font-weight: 700;
}
.cross-list li::before {
  content: "✕";
  position: absolute; left: 0; top: 0.05em;
  color: #b3455a;
  font-weight: 700;
}

/* ---------- FAQ ---------- */
.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-2) 0;
}
.faq-item:first-child { border-top: 1px solid var(--color-border); }
.faq-item summary {
  cursor: pointer;
  font-weight: 700;
  color: var(--color-primary-dark);
  font-size: 1.02rem;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-2);
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  font-family: var(--font-mono);
  color: var(--color-accent-dark);
  font-size: 1.3rem;
  flex-shrink: 0;
}
.faq-item[open] summary::after { content: "−"; }
.faq-item p { margin-top: 0.6rem; color: var(--color-text-muted); }

/* ---------- Bottom CTA ---------- */
.cta-final {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary));
  color: #eaf2f6;
  border-radius: var(--radius);
  padding: var(--space-4);
  text-align: left;
  margin: var(--space-2) 0;
}
.cta-final h2 { color: #ffffff; }
.cta-final p { color: #cfe2ea; max-width: 60ch; }
.cta-final .btn-row { display: flex; gap: var(--space-2); flex-wrap: wrap; margin-top: var(--space-2); }

/* ---------- Footer ---------- */
footer.site-footer {
  background: var(--color-primary-dark);
  color: #a9c4cf;
  padding: var(--space-4) 0 var(--space-3);
  font-size: 0.88rem;
}
footer.site-footer .wrap {
  display: flex;
  justify-content: space-between;
  gap: var(--space-3);
  flex-wrap: wrap;
}
footer.site-footer a { color: #dce8f0; }
footer.site-footer .foot-cols { display: flex; gap: var(--space-5); flex-wrap: wrap; }
footer.site-footer h4 { color: #ffffff; font-size: 0.85rem; margin: 0 0 0.6rem; text-transform: uppercase; letter-spacing: 0.05em; }
footer.site-footer ul { list-style: none; margin: 0; padding: 0; }
footer.site-footer li { margin-bottom: 0.4rem; }
footer.site-footer .bottom-line {
  border-top: 1px solid color-mix(in srgb, #ffffff 12%, transparent);
  margin-top: var(--space-3);
  padding-top: var(--space-2);
  font-size: 0.8rem;
  width: 100%;
}

/* ---------- Skip link ---------- */
.skip-link {
  position: absolute;
  left: -999px;
  top: auto;
  background: var(--color-accent);
  color: #06222c;
  padding: 0.6rem 1rem;
  z-index: 100;
  border-radius: var(--radius);
}
.skip-link:focus { left: var(--space-2); top: var(--space-2); }

/* ---------- Utility ---------- */
.text-muted { color: var(--color-text-muted); }
.mt-0 { margin-top: 0; }

@media (max-width: 640px) {
  body { font-size: 16px; }
  section { padding: var(--space-4) 0; }
  .hero { padding: var(--space-5) 0 var(--space-4); }
}