:root {
  --bg: #07110d;
  --panel: rgba(12, 27, 20, 0.86);
  --panel-strong: #0d1d15;
  --line: rgba(0, 255, 136, 0.16);
  --text: #ecf7f0;
  --muted: #8aa696;
  --faint: #557263;
  --green: #00ff88;
  --yellow: #ffd166;
  --red: #ff6b6b;
  --blue: #66d9ff;
}

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

body {
  margin: 0;
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
  background:
    linear-gradient(rgba(0, 255, 136, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 255, 136, 0.035) 1px, transparent 1px),
    radial-gradient(circle at 18% 0%, rgba(0, 255, 136, 0.14), transparent 34rem),
    radial-gradient(circle at 88% 18%, rgba(102, 217, 255, 0.08), transparent 30rem),
    var(--bg);
  background-size: 48px 48px, 48px 48px, auto, auto, auto;
}

a { color: var(--green); }

.shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--line);
  background: rgba(7, 17, 13, 0.86);
  backdrop-filter: blur(16px);
}

.site-nav {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  color: var(--green);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9rem;
  letter-spacing: 0.08em;
  text-decoration: none;
}

.nav-links {
  display: flex;
  gap: 16px;
  color: var(--muted);
  font-size: 0.84rem;
}

.nav-links a {
  color: inherit;
  text-decoration: none;
}

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

.writeup-shell {
  padding: 34px 0 70px;
}

.back-link {
  display: inline-flex;
  margin-bottom: 20px;
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.82rem;
  text-decoration: none;
}

.back-link:hover { color: var(--green); }

.writeup {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 28px;
  align-items: start;
}

.writeup-meta {
  position: sticky;
  top: 92px;
  padding: 22px;
  border: 1px solid var(--line);
  background: var(--panel);
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.35);
}

.meta-label {
  margin-bottom: 10px;
  color: var(--green);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.writeup-meta h1 {
  margin: 0 0 20px;
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  line-height: 1;
  letter-spacing: -0.04em;
}

.writeup-meta dl {
  display: grid;
  gap: 14px;
  margin: 0;
}

.writeup-meta dt {
  color: var(--faint);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.writeup-meta dd {
  margin: 3px 0 0;
  color: var(--text);
}

.badge {
  display: inline-flex;
  border: 1px solid currentColor;
  border-radius: 999px;
  padding: 3px 9px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.72rem;
  text-transform: uppercase;
}

.difficulty-easy { color: var(--green); }
.difficulty-medium { color: var(--yellow); }
.difficulty-hard { color: var(--red); }

.reader-note {
  margin-top: 22px;
  padding: 14px;
  border: 1px solid rgba(255, 209, 102, 0.22);
  color: #dbc992;
  background: rgba(255, 209, 102, 0.07);
  font-size: 0.86rem;
}

.writeup-content {
  min-width: 0;
  padding: 34px;
  border: 1px solid var(--line);
  background: rgba(7, 17, 13, 0.74);
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.35);
}

.writeup-content > h1:first-child {
  display: none;
}

.writeup-content h1,
.writeup-content h2,
.writeup-content h3,
.writeup-content h4 {
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.writeup-content h2 {
  margin-top: 42px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line);
  color: var(--text);
  font-size: 1.8rem;
}

.writeup-content h3 {
  margin-top: 30px;
  color: var(--green);
  font-size: 1.24rem;
}

.writeup-content p,
.writeup-content li {
  color: var(--muted);
}

.writeup-content strong {
  color: var(--text);
}

.writeup-content blockquote {
  margin: 22px 0;
  padding: 16px 18px;
  border-left: 3px solid var(--green);
  background: rgba(0, 255, 136, 0.07);
}

.writeup-content blockquote p {
  margin: 0.35rem 0;
}

.writeup-content code {
  color: #d7fff0;
  background: rgba(0, 255, 136, 0.08);
  border: 1px solid rgba(0, 255, 136, 0.13);
  border-radius: 4px;
  padding: 0.12rem 0.32rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.92em;
}

.writeup-content pre {
  overflow-x: auto;
  margin: 18px 0;
  padding: 18px;
  border: 1px solid rgba(0, 255, 136, 0.18);
  background: #04100a;
}

.writeup-content pre code {
  padding: 0;
  border: 0;
  background: transparent;
}

.writeup-content table {
  display: block;
  width: 100%;
  overflow-x: auto;
  border-collapse: collapse;
  margin: 22px 0;
}

.writeup-content th,
.writeup-content td {
  padding: 10px 12px;
  border: 1px solid rgba(0, 255, 136, 0.12);
  text-align: left;
}

.writeup-content th {
  color: var(--green);
  background: rgba(0, 255, 136, 0.07);
}

.writeup-content td {
  color: var(--muted);
}

.writeup-content img {
  max-width: 100%;
  border: 1px solid var(--line);
}

@media (max-width: 900px) {
  .writeup {
    grid-template-columns: 1fr;
  }

  .writeup-meta {
    position: static;
  }

  .writeup-content {
    padding: 22px;
  }
}

@media (max-width: 700px) {
  .nav-links { display: none; }
}