:root {
  --primary: #00b6ed;
  --primary-dark: #2581a3;
  --navy: #0d2a40;
  --dark: #0e1821;
  --bg: #f4f7f9;
  --text: #212529;
  --muted: #6c757d;
  --border: #dee2e6;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: Montserrat, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
}

main {
  flex: 1;
}

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

.container { width: 100%; max-width: 1100px; margin: 0 auto; padding: 0 1.5rem; }

/* Header */
.site-header {
  background: var(--dark);
  border-bottom: 1px solid rgba(255, 255, 255, .08);
}
.nav { display: flex; align-items: center; justify-content: space-between; height: 72px; }
.logo {
  display: block;
  height: 44px;
  width: auto;
  margin-left: -4px;
  filter: brightness(0) invert(1);
}
.nav-link { color: #fff; text-decoration: none; font-weight: 600; }
.nav-link:hover { color: var(--primary); }

/* Hero */
.hero { background: linear-gradient(135deg, var(--dark), var(--navy)); color: #fff; padding: 4rem 0 3.5rem; }
.hero h1 { margin: 0; font-size: clamp(2rem, 4vw, 3rem); font-weight: 700; line-height: 1.2; }
.hero time { display: block; color: var(--primary); font-weight: 600; margin-bottom: .5rem; }
.hero .lead p { margin: .75rem 0 0; font-size: 1.15rem; opacity: .85; }

/* Post list */
.posts { padding: 3rem 1.5rem; display: grid; gap: 1.5rem; }
.card {
  background: #fff;
  border-radius: 8px;
  padding: 2rem;
  box-shadow: 0 2px 12px rgba(13, 42, 64, .08);
  border: 1px solid rgba(13, 42, 64, .05);
}
.card time { display: block; color: var(--muted); font-size: .9rem; font-weight: 500; }
.card h2 { margin: .35rem 0 .75rem; line-height: 1.3; }
.card h2 a { color: var(--navy); text-decoration: none; }
.card h2 a:hover { color: var(--primary); }
.card p { margin: 0 0 1.25rem; }
.btn {
  display: inline-block; background: var(--primary); color: #fff; font-weight: 600;
  padding: .6rem 1.4rem; border-radius: 4px; text-decoration: none;
  transition: background-color .15s ease;
}
.btn:hover { background: var(--primary-dark); color: #fff; }

/* Single post */
.post { display: grid; grid-template-columns: 260px 1fr; gap: 2.5rem; padding: 3rem 1.5rem; align-items: start; }
.toc {
  position: sticky;
  top: 1.5rem;
  background: #fff;
  border-radius: 8px;
  padding: 1.5rem;
  font-size: .9rem;
  box-shadow: 0 2px 12px rgba(13, 42, 64, .08);
}
.toc strong {
  display: block;
  color: var(--navy);
  font-size: .8rem;
  text-transform: uppercase;
  letter-spacing: .05em;
  margin-bottom: .75rem;
}
.toc ul { list-style: none; padding-left: .85rem; margin: .35rem 0 0; }
.toc > nav > ul { padding-left: 0; margin-top: 0; }
.toc li { margin-top: .45rem; line-height: 1.4; }
.toc a { display: block; text-decoration: none; color: var(--navy); }
.toc a:hover { color: var(--primary); }
.content {
  background: #fff;
  border-radius: 8px;
  padding: 2.5rem;
  min-width: 0;
  box-shadow: 0 2px 12px rgba(13, 42, 64, .08);
}
.content h2, .content h3, .content h4 { color: var(--navy); scroll-margin-top: 1rem; line-height: 1.3; }
.content h2 { border-bottom: 3px solid var(--primary); padding-bottom: .3rem; margin-top: 2.5rem; }
.content h2:first-of-type { margin-top: 1.5rem; }
.content h3 { margin-top: 2rem; margin-bottom: .5rem; }
.content h4 { margin-top: 1.5rem; margin-bottom: .5rem; }
.content img { display: block; max-width: 100%; height: auto; margin: 1.25rem 0; border: 1px solid var(--border); border-radius: 6px; }
.content li { margin-bottom: .4rem; }
.content pre { background: var(--dark); color: #fff; padding: 1rem 1.25rem; border-radius: 6px; overflow-x: auto; }
.content code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .9em; }
.content :not(pre) > code { background: var(--bg); color: var(--navy); padding: .15rem .4rem; border-radius: 4px; }
.callout { border-left: 4px solid var(--primary); background: #e6f8fd; padding: 1rem 1.25rem; border-radius: 4px; margin-bottom: 1.5rem; }
.callout strong { display: block; color: var(--navy); margin-bottom: .25rem; }

/* Footer */
.site-footer {
  margin-top: auto;
  background: var(--dark);
  color: #bbc2cb;
  padding: 2rem 0;
  font-size: .9rem;
}
.site-footer .container { display: flex; align-items: center; gap: 1.5rem; flex-wrap: wrap; }
.site-footer a { color: #fff; text-decoration: none; }
.site-footer a:hover { color: var(--primary); }
.site-footer span { margin-left: auto; }

@media (max-width: 800px) {
  .post { grid-template-columns: 1fr; }
  .toc { position: static; }
  .content { padding: 1.5rem; }
}